Livestock Feed Resources and Feed Evaluation in Europe Present Situation and Future Prospects

LIVESTOCK PRODUCTION SCIENCE Official Journal of the European Association for Animal Production (E.A.A.P) Revue Officielle de la F&d&ration Europ~enne de Zootechnie (F.E.Z.) Offizielle Zeitschrift der Europ~ische Vereinigung for Tierzucht (E. V. T.) Odt3HLIHa/IBHBll;I )KypHa.a EBponeficKofi ACCO[IHauHH NO )K~BOTHOBOACTBy(E.A.)K.)

Editors R D. Politiek (Wageningen, The Netherlands): Editor-in-chief H. de Boer (Zeist, The Netherlands) Honorary Editor-in-Chief J. Boyazoglu (Roma, Italy): E.A.A.P. Secretary General E. Wagner (Luxembourg): Newsletter G. Brem (Munich, Federal Republic of Germany) Ch. Gall (Hohenheim, Federal Republic of Germany) Y Henry (Rennes, France) W.G. Hill (Edinburgh, Gt. Britain) H. Karg (Munich, Federal of Republic of Germany) A. Figueiredo Nunes (Santar~m, Portugal) V. ~stergaard (Foulum, Denmark) J.P. Signoret (Nouzilly, France) M. Soller (Jerusalem, Israel) J D. Wood (Langford, Gt. Britain) Editorial Advisory Board T C. Cartwright (College Station, TX, U.S.A.) M. Cicogna (Milano, Italy) E.P. Cunningham (Castleknock, Ireland) C). Dannell (Uppsala, Sweden) J.C. Flamant (Castanet-Tolosan, France) J.F. O'Grady (Dunsany, Ireland) J. Hodges (Roma, Italy) A. Horn (Budapest, Hungary) R. Jarrige (Theix, France)

L. Ollivier (Jouy-en-Josas, France) K. Rohr (Braunschweig, Federal Republic of Germany) G. Sch5nmuth (Berlin, German Democratic Republic) H. Staun (KeJbenhavn, Denmark) F. Torres (Cali, Colombia) J. Unshelm (Menchen, Federal Republic of Germany)

VOLUME 19 (1988)

ELSEVIER, A m s t e r d a m

- Oxford - New York - Tokyo

XXV

Procedure of the Study GENERAL The working group for this study was set up by the commission on Animal Nutrition of the E.A.A.P. in autumn 1984. It concentrated on compiling technical data, because economic and structural development information is treated exhaustively in the E.A.A.P. issue of 1982. The study includes the updating of information on the availability of forage crops, cereals and other seeds and of by-products of agro-industrial origin. In addition, the nutritional value of these feeds has to be defined. New results of research into the metabolism of nutrients suggested a move onto new evaluation systems. This entailed a shift in the ranking of the economic value of the feeds, and thus in the feed and feeding policy, not only for the farmer but also on the level of international trade. This study deals largely with this topic. While progressing in the study, the group decided that neither problems of import and export of feedstuffs nor a production budget for Europe should be tackled. The reader is referred in this respect to current studies under the auspices of the Organization of Economic Cooperation and Development ( O.E.C.D. ) and the European Economic Community (E.E.C.). WORKING GROUP MEMBERS AND OTHER AUTHORS Members of the working group were experts, invited from various countries/regions in Europe. They were encouraged to contact colleagues elsewhere in Europe to support them. Thus the working group could be kept small and efficient. The group held four plenary sessions-two in Ziirich and two in Brussels-to discuss the work's progress and the drafted chapters. In addition part of the group convened during the E.A.A.P. study meetings in Greece, Hungary and Portugal. The members of the working group were F. de Boer, Institute for Livestock Feeding and Nutrition Research ( I.V.V.O ), Lelystad, The Netherlands (Chairman) J.L. Tisserand, Ecole Nationale Supdrieure des Sciences Agronomiques Appliqu~es, Dijon, France (Secretary) G. Alderman, University of Reading, United Kingdom H. Bickel, Institute of Animal Sciences, Swiss Federal Institute of Technology, ETH-Zentrum, Ziirich, Switzerland Ch. V. Boucqu~, Rijksstation voor Veevoeding, Melle-Gontrode, Belgium 0301-6226/88/$03.50

© 1988ElsevierSciencePublishersB.V.

xxvi Y. Henry, Institut National de Recherches Agronomiques (I.N.R.A.), Centre de Rennes, Saint-Gilles, France Y. van der Honing, Institute for Livestock Feeding and Nutrition Research (I.V.V.O.), Lelystad, The Netherlands J. Lee, Agricultural Institute, Wexford, Ireland A.P. Namur, F~d~ration Europ~enhe des Fabricants d'Aliments Compos~s, Brussels, Belgium F. Sundst~l, Agricultural University of Norway, As, Norway S. Szentmihalyi, Institute for Animal Nutrition, Herceghalom, Hungary (died in 1985 and succeeded by N. Todorov ) N. Todorov, Institute of Zootechnics and Veterinary Medicine, Stara Zagora, Bulgaria H. Vogt, Institut fiir Kleintierzucht der F.A.L., Celle, Federal Republic of Germany H. Zlatic, Institute for Animal Husbandry and Dairy Science, Zagreb, Yugoslavia (left the working group prematurely for health reasons and was succeeded by P.E. Zoiopoulos ) P.E. Zoiopoulos, Feedingstuffs Control Laboratory, Lykovrisi Attikis, Greece. In addition the following authors contributed to the study: E. Austreng, B. Grisdale-Helland, S.J. Helland and T. Storebakken, Institute for Aquaculture Research, As, Norway L.O. Fiems, Rijksstation voor Veevoeding, Melle-Gontrode, Belgium F. Lebas, Institut National de Recherches Agronomiques (I.N.R.A.), Centre de Toulouse, Castanet-Tolosan, France E.L. Miller, University of Cambridge, Cambridge, England J. Morel, Swiss Federal Research Station for Animal Production, Grangeneuve, Switzerland K.P. Parris, Organization for Economic Cooperation and Development ( O.E.C.D. ), Paris, France A.H. Tauson, Swedish University of Agricultural Sciences, Uppsala, Sweden. F. Malossini, Faculty of Agriculture, University of Udine, Italy provided valuable help in checking various chapters for particular aspects involving Mediterranean countries. SUPPORTINGORGANIZATIONS The study has been stimulated considerably by a series of organizations, who have sponsored the work financially or materially. This highly-appreciated support was provided by - Commission of the European Communities, Brussels

xxvii - F~d~ration Europ~enne des Fabricants d'Aliments Compos~s (F.E.F.A.C.), Brussels - Merck, Sharp and Dohme, Brussels - Monsanto Europe, Brussels

Federal Republic of Germany H. Wilhelm Schaumann Stiftung zur FSrderung der Agrarwissenschaften, Hamburg

-

France - Compagnie Franqaise de Nutrition Animale (C.O.F.N.A.), Tours - Guyomarc'H, Vannes - Lilly France, Saint Cloud Organisation Nationale Interprofessionnelle des Ol~agineux, Paris Pioneer France Mais, Toulouse Roussel-U.C.L.A.F., Paris Unigrains, Paris Union Nationale Interprofessionnelle des Proteagineux, Paris -

-

-

-

-

Greece Hellenic Society of Animal Production, Athens Elviz, S.A., Hellenic Feedstuffs Industries, Plati Imathias

-

-

Ireland Irish Corn and Feed Association, Dublin

-

Italy Associazione Italiana di Allevatori, Rome

-

The Netherlands -

Produktschap voor Veevoeder, Den Haag

Norway -

-

-

-

-

Kraftforimport~renes Landsforening, Oslo Norkorn, Oslo Norsk M~lleforening, Oslo Norske Felleskj~p, Oslo Statens Kornforretning, Oslo

Sweden AB Cardo, Malm5 - Sollebolagen AB, Uddevalla Svenska L a n t m a n n e n s Riksforbund, Stockholm -

-

oo, XXVlll

- Svensk Oljeextraktion, Karlshamn Switzerland

Hoffman-La Roche, Basel Migros Genossenschaftsbund, Ztirich - V e r e i n i g u n g der Landwirtschaftlichen Genossenschaftsverbande Schweiz, Winterthur Vereinigung Schweizerischer Futtermittelfabrikanten, Zellikofen -

-

der

United Kingdom

British Society of Animal Production, Penicuik - Eli Lilly Co., London Paul's Agriculture, Ipswich -

Highly-appreciated support was also received from the Institute for Livestock Feeding and Nutrition Research ( I.V.V.O. ) in Lelystad, as well as from the Institute of Animal Sciences, Swiss Federal Institute of Technology, ETH Zentrum, Ztirich, which provided mailing, typing and other facilities. We thank all group members and other authors for their great efforts to complete the task in the time scheduled, in spite of the daily obligations in their professional positions. The editors pay special tribute to G. Alderman, University of Reading (U.K.) for the linguistic revision of various texts. PROF. DR. H. BICKEL President (1980-1986) E.A.A.P. Commission on Animal Nutrition

IR. F .

DE

BOER

Chairman E.A.A.P. working group

Livestock Production Science, 19(1988)1

1

Elsevier SciencePublishersB.V., Amsterdam-- Printed in The Netherlands

Foreword

It is generally recognized that feed is the most important single item in livestock production costs. Thus awareness of the feed resources, and knowledge of the nutritional value of feedstuffs in order to feed the animal adequately to its requirement, are as essential as the knowledge of the genetic potential of the animals and of the management of production. In 1982 Politiek and Bakker edited the E.A.A.P. long range study "Livestock Production in Europe, Perspectives and Prospects". It provides a wealth of qualitative and quantitative information on European livestock production. Livestock feeding is touched on in various chapters of that study but in a rather general way. The Commission on Animal Nutrition of the European Association for Animal Production, therefore, decided to set up a working group to collect information about animal feeds in the European context. This book, published as a double issue of the E.A.A.P. journal "Livestock Production Science", is the report of the working group. Some 25 specialists generously contributed their time and knowledge to the study. The best thanks are due to all those who contributed to this important study. Credit is specially paid to Ir. F. de Boer, Chairman of the Working Group, and Prof. Dr. H. Bickel, President of the E.A.A.P. Commission on Animal Nutrition during the relevant period, for their efficient leadership of the work. A number of international and national organisations within the agricultural industry have kindly sponsored the study. Many thanks are due to them for this valuable support. ARNE ROOS President European Association for Animal Production

Livestock Production Science, 19 (1988) 3-10 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

3

I. I M P A C T OF F E E D IN L I V E S T O C K PRODUCTION F. DE BOER and H. BICKEL INTRODUCTION

The economic production of livestock products as human food is achieved by combining a number of factors, which are under the control of the livestock farmer. He has to combine the effects arising from the genotype and health of the animal with optimal nutrition and environmental conditions. Livestock research, education and extension have been concerned with these factors for a long time. The magnitude of effort in the different sectors in the past has not been equal, nor closely co-ordinated. The breeding of animals was the first area to receive a great deal of attention, resulting in remarkable progress in increasing the productive potential of the various types of livestock: cattle were bred specifically for their ability to produce milk or meat, or even to be dual purpose; pigs were bred to produce varying proportions of lean-to-fat ratios in the carcase, whilst poultry were bred either primarily for egg production or for meat production. Many different types of sheep breeds have been evolved with the production of wool as an additional parameter. At first, breeding goals were more concerned with typical shape and colour traits, with the presumption that these were related to production characteristics, often leading to exaggerated emphasis on these characteristics, as can still be seen in the livestock show rings today. Nevertheless, supported by the results of modern genetic research activity, the end result has been the breeding of highly-productive livestock for many different purposes. Animal health, or freedom from animal disease, has also been a major sector of research, development and application in livestock production. In contrast to livestock breeding, its effects on livestock productivity is often striking, particularly the ability to cure or prevent a particular disease. The establishment of the nutrient requirements of animals and reliable systems for feed evaluation has taken a great deal of time, but farmers can alter the way they feed their livestock quite rapidly, and affect livestock production considerably in this way. The striking effects of feeding upon livestock production are probably responsible for the farmers saying "First feeding, then breeding". This statement does not imply that priority should be given to feeding above breeding, or the reverse, but rather that animal breeding cannot be done successfully in the absence of good feeding. Nowadays, because of the very high genetic potential of European livestock, 0301-6226/88/$03.50

© 1988 Elsevier Science Publishers B.V.

and the sophisticated and still-developing animal feeds and nutritional science, concerted action by both disciplines, together with animal-health programmes, is essential for further progress in livestock production. The goal of sustaining high levels of yield for long periods will only be reached, however, if optimal environmental conditions such as housing, climatic conditions and farm management, are provided. Such factors have been less important when animal production levels were at a more moderate level, but in the current sophisticated systems, with high levels of individual production by animals, their influence is becoming increasingly important. The pursuit of high individual production levels in livestock is economically feasible, because the fixed costs of the livestock-production system, involving housing, capital investment, equipment and so on, are spread over a greater quantity of output and their effects are reduced in the overall costs of production. FEED COSTS AND EFFICIENCYIN LIVESTOCKPRODUCTION At the physiological level, the amount of feed used per unit of livestock product depends mainly on the ratio of food energy output by livestock, related to the animal feed-energy input. Other criteria such as protein in both food and feed can also be considered. However, the efficiency of feed energy utilisation is by far the most important and comprehensive measure by which to judge the efficiency of animal-feed usage. Two levels of efficiency of feed energy utilisation can be defined: (1) the animal level, i.e. the efficiency of energy utilisation by the individual animal; (2) the production-system level, i.e. the efficiency of energy utilisation by the whole production system. The efficiency of energy utilisation at the animal level improves as the ratio of production energy increases, in relation to the animal's maintenance requirement, i.e. increasing the animal's level of production. The amount of feed used per unit of livestock product decreases accordingly. However, the law of diminishing returns will also apply beyond a certain point, depending on the type of livestock production involved, which may result in lower profitability of higher production levels. The energy value of the animal feed itself, the livestock products, and the partial efficiency of feed energy utilisation for the particular livestock product, all influence total efficiency, and thus overall feed costs (Bickel, 1977). However, judging feed efficiency merely on the level of the individual animal production, may give a biased picture. Blaxter (1969) stressed that the efficiency of the complete production system has to be taken into account. This means that the number of offspring of the parent generation, the production costs of rearing these, and their replacement rate, should be considered when making a final judgement of the complete system. The output of food produced by the system, has to be compared to the total feed input to the system. Ex-

TABLE 1 Efficiencyof foodproductionby livestock-productionsystems Calculationbasedon

Dairy cattle Beefcattle Pigs Hens Broilers

Gross Energy

Gross Protein

H a

Bb

H

B

0.12 0.11 0.17 0.11 0.10

0.12-0.19 0.06 0.21 0.15 0.16

0.23 0.06 0.12 0.18 0.20

0.21-0.28 0.11 0.16 0.31 0.26

aH= Holmes (1970). bB = Bickel (1977). amples of the efficiency of feed utilisation, considering all these factors, are given in Table I, as calculated by Holmes (1970) and Bickel (1977): It is evident that the efficiencies of various total-production systems vary according to the energetic efficiency of the individual animal, its prolificacy, longevity and replacement rate. Irrespective of differences in these parameters, pig-production systems show the highest levels of efficiency, and beef production, when not combined with milk production, the least efficient use of feed energy. Of all the costs involved in the various animal-production systems, feed costs are the most important single item. This is illustrated in Table II for some countries, although the method of calculation differs for each country. It is obvious that feed costs as a percentage of total production costs vary with the livestock-production system. If the fixed costs, such as calf rearing, housing and capital investments are high, the farmer will try to reduce these costs per unit of product by increasing the production level. If the financial income from the livestock product is smaller than the total cost of production required to maintain and manage the livestock unit, the farmer or the unit will lose money, and probably ultimately stop production. Thus, controlling production costs of the system is a very important aspect of management of livestock-husbandry systems. Farmers can affect many of these factors themselves, whereas affecting the selling price of the product is far more difficult. Increasing individual animal productivity is not without its risks to the longevity and health of the animals involved. Overcoming such problems requires careful integration of the disciplines involved in livestock husbandry, environment, breeding, feeding and health care. If these important areas are given careful attention, very high individual production levels can be achieved without adverse effects (de Boer, 1986).

6 TABLE II Feed costs as percentage of total costs of livestock farming, costs of family labour on farm excluded, in some countries Country

Veal Beef Milk Pigs

Poultry

Source

Breeding Fattening Hens Broilers Belgium

65

55

42

46 44

Denmark France

18 34 69 43 14 65

F.R.G. Greece Ireland Italy Luxemburg Netherlands

28 28 46 33 64 44 60 49 44

82

82

85

70

63

66

70 75 74

63

83 58

69

82

86

69

64 83 84

64 83 59

64

76 62

64

68

Norway

59

55 60

Switzerland

48

46

45

51

54

58

U.K. Yugoslavia

20

23 14

44 34

42

74 40

52

Buyle (1984) Goffinet (1984) Buyle (1986a, b) F.A.D.N. (1986) F.A.D.N. (1986) Teffene and Vanderhaegen (1986) Stevens (1987) F.A.D.N. (1986) F.A.D.N. (1986) F.A.D.N. (1986) Lee (1987) a F.A.D.N. (1986) F.A.D.N. (1986) F.A.D.N. (1986) Wisselink (1984) b F.A.D.N. (1986) Sundstol, Homb and Herstadt (1987) c Bickel (1987) d S.B.V. (1986) F.A.D.N. (1986) Zlatic (1987) e

aj. Lee, personal communication, 1987. bG.j. Wisselink (1984), personal communication based on Landbouwcijfers. LEI, s'Gravenhage. CF. Sundstol, Th. Homb and O. Herstad, personal communication, 1987. dH. Bickel, personal communication, 1987. Based on "Schweizerischer Bauernverband" Brugg and on "Verband Schweizerischer GefRigelhalter". Zollikofen. ell. Zlatic, personal communication, 1987. Figures are an average of regions with very different production conditions. The purchase price of animals is relatively high, thus causing relatively low figures for feed costs. FEEDSANDFOODS

Although physiological efficiency calculations concerning feed energy utilisation are essential for the understanding of the differences in feed-conversion ratios between animal species, they do not explain why production systems with low efficiencies of energy utilisation are not only maintained but even promoted in some areas. This is a consequence of the competition between mankind and animals for food resources. The proportion of animal feed which

T A B L E III Area utilizable for agriculture (106ha) (F.A.O., 1973, 1985; S.B.V., 1986) World

Arable land Pastures Ratio of pastures to arable land

Netherlands

Switzerland

1973

1984 a

1973

1984 ~

1972

1985 a

1985 b

1460 2990

1476 3151

0.8 1.3

0.9 1.1

0.3 1.7

0.3 1.7

0.3 0.8

1.6

1.2

6.2

6.2

2.7

2.0

2.1

aAdded to original table. bWithout Alpine pastures.

is readily acceptable as food for human nutrition has to be taken into account in this matter. A number of animal feeds are suitable for human food as well, cereals being a classic example, but there are others such as skimmed milk powder, peas, potatoes and some byproducts such as wheat bran. The use of such products as feed for livestock is criticised by some people who are concerned about human societies suffering from shortages of food. Some go so far as to suggest that livestock husbandry should be discontinued or reduced in scale. They suggest that all land occupied by feed suitable for livestock should be used instead for the production of human food. These criticisms are backed up by citing the efficiency rations of food production by animals and food production by arable crops. Invariably these comparisons come out in favour of primary food production by plants. There is no argument about that fact, but the picture is an over-simplification. This questioning of the continuance of any form of livestock husbandry overlooks the fact that large areas of the world (and Europe) are unsuited for the production of food crops, as shown in Table III, (de Boer, 1975). Table III shows that there is twice as much pasture as arable land in the world. Even in areas with a high percentage of "utilised agricultural area" (UAA), as in The Netherlands, the area of pasture exceeds the area of arable land. This is particularly the case in Alpine regions such as Switzerland. Vegetation from pastures can only be utilised efficiently by ruminant livestock, cattle, sheep and goats. This is also true for the large amounts of byproducts now produced by the food-processing industries. Such vegetation and by-products generally cannot even be utilised by human beings at all. The use of ruminant livestock therefore, is a necessity, in order to produce food from these sources, and so act as a two-stage primary-food producer (de Boer, 1980 ). Schtirch (1975) stresses this fact, stating that maximally, only 25% of the total animal feed used for ruminant production can be used directly for human nutrition. This p h e n o m e n o n of a two-stage primary-food production system requires a different approach in calculating feed-utilisation efficiency ratios.

8 TABLE IV Yield of food energy and protein of animal origin in relation to energy and protein input, which would be directly acceptable to human nutrition Energy E" Milk from dairy cattle Beef Milk and beef (double-purpose breeds) Pork Eggs Poultry meat

Protein Bb

2.30 1.30 (0.41) ~ 0.40 0.23 0.29

E 3.0 2.7 (0.94) ~

1.2 0.4 0.2 0.3

0.34 0.40 0.43

aE = van Es (1978). bB = Bickel et al. (1979). CCereal-based intensive feedlot system.

Although the calculations of efficiency of feed-energy utilisation are correct when comparing individual animals or production systems, they do not deal satisfactorily with the problem if man and animals compete for the same food resource. Differences in the proportion of feed acceptable to both human and animal nutrition vary with animal species and production systems. Van Es (1978) and Bickel et al. (1979) have calculated the ratio of animal-product energy related to the food energy utilised by these animals which would have been directly acceptable for h u m a n nutrition (Table IV). Table IV shows clearly, for example, that cows produce 2.3 times more humanly-acceptable food energy by converting roughage to food than that which would be directly available from arable land. It is also clear from the data that feeding concentrates to non-ruminants, pigs and poultry, does utilise food suitable as human food. Just as in the case of the ruminants however, some of these concentrates can be partly replaced by by-products. However, transport costs, the lack of an adequate infrastructure and purchasing power in many parts of the world, prevent farmers responding rapidly to economic trends, so that we may not see much change in the near future in this area. LIVESTOCK FEEDING, CONSUMERHEALTH AND ENVIRONMENTAL POLLUTION

Increased concern is being expressed these days about possible health risks to the population from the consumption of food being produced by modern agriculture. There is also increasing concern about pollution of the environment arising from aspects of livestock production. Such concerns deserve appropriate and adequate attention. In the case of livestock husbandry, animal

feeds are used as carriers for a wide range of additives, which are very beneficial to the livestock concerned. Consumers, however, need to be reassured that no trace of these additives is present in the food that they purchase for eating. Sometimes animal feeds also contain other agents, such as moulds or bacteria, which may be harmful to consumers. Whilst animals possess, as do humans, a sophisticated physiological purification system (the liver and kidneys ), which often but not always prevents the passage of such contamination, a continuous awareness of these risks is needed. The increasing pollution problem arising from livestock production is due to the fact that roughly 40% (Bickel et al., 1979) of the feed energy ingested is excreted as waste: faeces and urine. Apart from causing complaints in denselypopulated areas about serious and offensive odours, the accumulation of various mineral elements in soil and in surface water may also cause problems. The quality of drinking water may be impaired in the long run, and natural vegetation may also suffer from the mineral imbalances. Appropriate alterations in feeding technology and quality may alleviate these problems. For example, it has been shown that the excessive pollution by phosphorus on pig farms can be successfully restricted by lowering the level of phosphorus addition to feeds, and by utilising the intrinsic phosphorus in feeds, particularly that associated with phytate, more efficiently, {Jongbloed, 1987 ). It is possible that the pollution by other elements, particularly heavy metals, could be curtailed substantially in a similar manner. It is evident that livestock farmers, in accepting new developments in animal nutrition, must ensure that any risk to consumer health and environmental pollution is excluded when adopting such new techniques.

REFERENCES Bickel, H., 1977. Der Futteraufwand in der Rindviehproduktion unter Beriicksichtigung des Wirkungsgrades der Energieverwertung. Schweiz. Landwirtsch. Forsch., 16: 175-214. Bickel, H., Schiirch, A., Zihlmann, F., Studer, R. and Fiissler, P., 1979. Energieaufwand und Energieertrag in der Tierproduktion. Ber. Landwirtsch. Sonderh., 195: 31-39. Blaxter, K., 1969. Efficiency of Farm Animals in Using Crops and Byproducts in Production of Foods. Proc. 2nd World Conf. Anim. Prod., Bruce Publ. Co., St. Paul, MN, pp. 31-40. Buyle, A., 1984. La rentabilit~ de l'engraissement de taurillons. Rev. Agric. (Brussels), 37: 672-683. Buyle, A., 1986a. La rentabilit~ des productions avicoles dans les exploitations sp$cialisSes. (Exercice 1985-1986); Inst. Econ. Agric. Publication no. 473. Buyle, A., 1986b. La rentabilit~ des productions porcines dans les exploitations sp~cialisSes. {Exercice 1985-1986), Inst. Econ. Agric., Bruxelles. Publication no. 474. De Boer, F., 1975. Van wat de mens niet lust of smaakt wordt door het vee iets goeds gemaakt. Bedrijfsontwikkeling, 6: 131-135. De Boer, F., 1980. Bij- en afvalprodukten als veevoer. Diergeneeskd. Mere., 27: 203-211. De Boer, F., 1986. Perspectives of bovine production. From cow to supercow? In: DSA (Bureau Europden d'Information pour le D~veloppement de la Sant~ Animale), Symposium proceed-

10 ings: Future Production and Productivity in Livestock Farming: Science versus Politics, Elsevier, Amsterdam, pp. 21-36. F.A.D.N. (Farm Accountancy Data Network), 1986. Document 1982/1983-1983/1984; Office for official publications of the European communities; Luxembourg. Data provided by K.J. Poppe, LEI,'s Gravenhage. F.A.O., 1973. Production Yearbook, Vol. 27, F.A.O., Rome. F.A.O., 1985. Production Yearbook, Vol. 39, F.A.O., Rome. Goffinet, R., 1984. Structure du prix de revient du lait pour un ~chantillon d'exploitations avec 40 60 vaches et un rendement laitier compris entre 4000 et 5000 litres. Communication interne, Inst. Econ. Agric., Bruxelles. Holmes, W., 1970. Animals for food. Proceedings of the Nutrition Society. 29: 237-244. Jongbloed, A.W., 1987. Phosphorus in the feeding of pigs. I.V.V.O., Lelystad. Thesis, 343 pp. S.B.V., 1986. Statistische Erhebungen und Schiitzungen: 63. Schweizerischer Bauernverband, Brugg. Sch~irch, A., 1975. Kongressband 1974; Die Bedeutung der Tierproduktion fiir die Sicherung der zukiinftigen Ern~ihrung. Landwirtsch. Forsch., Vol. 31. Erstes Sonderheft, pp. 21-35. Teffene, O. and Vanderhaegen, J., 1986. Economie des productions porcines. In: J.M. Perez, A. Rerat and P. Mornst (Editors), Le porc et son ~levage. Bases scientifiques et techniques. Maloine, Paris, pp. 503-565. Van Es, A.J.H., 1978. Losses and gains of energy during production of food for human consumption in animal husbandry. Agric. (Leuven), 23: 359-374.

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II. F E E D S T U F F S II. 1. I n t r o d u c t i o n F. DE BOER

Any product of vegetable or animal origin may be classified as a feedstuff, provided animals are capable (without risk to their health) of utilizing its organic and inorganic components. This implies that there is a large variety of feedstuffs and, therefore, classifying feedstuffs is a necessity. Roughages (or forages) and concentrates are generally accepted as classes of feedstuffs. Trying to define in an appropriate and simple way a set of criteria for them is fairly difficult, but it is nevertheless very useful for statistical purposes. Crude-fiber content is often a criterion for characterizing both groups of feedstuffs; in general roughages contain more and concentrates contain less than 18% crude fiber (Crampton, 1956). Even so, feedstuffs in each group show considerable variety. Fresh feed, such as grass, would belong to the group of concentrates. It is nevertheless classified as a roughage because of its high moisture content, which means a low level of nutrients per unit of weight. This also applies to other feedstuffs when their moisture content is more than 40% (O.E.C.D., 1985). Roughages and concentrates may therefore be characterized along three criteria as shown below

Roughages Concentrates

Dry-matter content in feed

Level of nutrients per unit weight of feed

Crude-fiber content in feed

< 60 > 60

Low High

> 18 < 18

The statistical Office of the European Economic Community (Eurostat) splits feedstuffs in groups that are marketable and not marketable, broadly covering concentrates and roughages respectively. However, when considering single feedstuffs from both groups individually it is easy to find exceptions to these rules. Some roughages, such as first-class wilted silage, may approach or even enter the class of concentrates, while a feedstuff such as artificially-dried grass - clearly a marketable f e e d - belongs, according to its crude-fiber content, 0301-6226/88/$03.50

© 1988 Elsevier Science Publishers B.V.

12 to the group of roughages. In general, however, the criteria quoted above permit feedstuffs to be classified in a very acceptable way. In the class of concentrates cereals traditionally play a predominant role. In some regions, however, this picture has changed considerably and cereals have been partly replaced by cereal substitutes such as manioc, while simultaneously by-products from food industries have gained more and more importance as well. By-products, of vegetable as well as of animal origin, form a "floating" class of feeds. Technology of feed processing into food produces a continuous and ever changing flow of by-products. Some of these (oilmeals) have a long and reputable history, others became available more recently, and yet new ones will come into the picture in future. Compound-feed industries have combined these various concentrates into compound feeds, and these have made a very big impact on livestock production today. Based on this pragmatic approach, the following chapters will illustrate in more detail the impact of forages, cereals and other seeds, by-products of vegetable and animal origin and compound feeds for livestock feeding in Europe.

REFERENCES Crampton, E.W., 1956. AppliedAnimal Nutrition. W.H. Freeman and Co., San Francisco, CA, pp. 3-11. O.E.C.D., 1985. The O.E.C.D. Feed Supply Utilization Account (F.S.U.A.): A methodologyto completeF.S.U.A.sat a national level.O.E.C.D., Paris (Mimeograph).

Livestock Production Science, 19 (1988) 13-46

13

Elsevier SciencePublishers B.V., Amsterdam-- Printed in The Netherlands

II. 2. Forages JOHN LEE INTRODUCTION General

In the broadest sense, forage refers to the vegetative portions of plants that are consumed by animals and for the purpose of this review embraces natural and artificial or sown grassland, annual and perennial green fodder from arable land and certain crop residues. It includes pasture, rough grazing, hay, silage, root crops, forage maize, straw and certain root tops. Rough grazing land denotes communities of natural plants that are grazed or browsed. Forages have a bulky nature in comparison to concentrates. Thus, bearing in mind the capacity of the rumen and the filling effect of forages in the gut, supplementary feeding with concentrates is frequently practised to satisfy nutritional needs. As increasing amounts of supplementary concentrates are fed, the ruminant animal eats less forage. In many cases supplementary concentrates partly replace rather than supplement the forages with which they are fed. Feeding very high concentrate levels may even decrease intake of forage, and result in a change in composition of volatile fatty acids in the rumen to an extent which brings about ruminant disorders. The large variability in feed composition is illustrated in Table I, which presents some examples of major forages from various regions in Europe. Grass, which is the major component of the forages, has the advantage of being, to a large degree, a complete diet for ruminants in most circumstances. However, it is not balanced for all possible animal production purposes and has a variable composition, in contrast to cereals which have a high and consistent energy value, and therefore compared with grass are more predictable and easier to feed. Young leafy grass has, for example, an excess of protein combined sometimes with a high soluble-carbohydrate content. The forages may be conveniently categorised under the headings grassland, root crops and green fodder from arable land, the latter two comprising annual fodder crops. Table II shows the extent of the major forages. Permanent grassland is the most significant, in terms of areal extent, with temporary grassland being particularly significant in Denmark. Temporary grassland also has a major significance in Fennoscandia (Finland, Sweden and Norway), where the grassland balance comprises 2.0 Mha under leys and 0.7 Mha under permanent 0301-6226/88/$03.50

© 1988ElsevierSciencePublishersB.V.

14 TABLE I Examples of forage composition in Europe Forage

Dry matter (gkg -1 forage)

Fresh grass N 140-305 M 183-280 E 168-340 Grass hay N 882-951 M 859-936 E 840-883 Oat and vetch hay M 790-862 Grass silage N 177-585 E 154-265 Maize silage N 240-350 M 233-397 E 143-350 Maize stover M 291-916 E 334-421 Potatoes N 219-221 E 231-257 Sugarbeetleaves andtops, ensiled N 180-230 M 178 E 133 Fodderbeets N 127-214 E 133

Organic matter (g kg -~ DM)

Crude protein (g kg -1DM)

Crude fibre (gkg -1 DM)

Metabolisable energy (MJ kg -1DM)

810-937 860-930 880-945

63-259 80-174 65-195

167-359 174-320 201-370

7.0-13.2 7.1-12.0 6.4-11.4

844-942 851-940 879-950

52-199 75-196 76-175

172-397 244-389 235-371

5.9-12.9 7.7-9.7 5.1-9.8

870-929

74-158

268-333

8.3-9.6

861-953 863-927

90-260 102-203

185-360 229-348

6.7-12.1 7.3-11.9

961-967 929-951 905-944

78-106 81-94 68-109

165-275 206-273 214-353

7.5-11.7 9.7-9.9 8.3-9.9

889-940 883

44-54 81-84

292-362 346-370

6.3-8.0 7.8-7.9

926-949 953-954

90-113 73-83

22-33 27-28

11.8-13.4 10.9-11.0

670-678 652 917

104 90 110

907-948 917

55-76 110

135-148 107 73 43-128 73

7.9 7.7 10.3 11.6-12.5 10.3

N = North and Western Europe; M = Mediterranean area; E = Eastern Europe. References for N: I.N.R.A., 1978; D.L.G., 1982; LTK, 1982; M.A.F.F., 1986; Centraal Veevoederbureau, NL, 1983. References for M: I.A.M.Z., 1981, 11. References for E: Berlacu, 1983; N. Todorov, personal communication, 1970.

p a s t u r e . R o o t c r o p s a r e s i g n i f i c a n t in P o l a n d , a n d a r a b l e g r e e n f o d d e r ( l a r g e l y f o r a g e m a i z e ) h a s a m a j o r s i g n i f i c a n c e in F r a n c e , I t a l y a n d D e n m a r k in particular. F o r a g e s f r o m t h e a b o v e s o u r c e s a r e f e d to r u m i n a n t a n i m a l s b e c a u s e t h e y

15 TABLE II Extent of major forages ( 103 ha) Permanent grassland

Austria Belgium Bulgaria Czechoslovakia Denmark France Finland F.R.G. G.D.R. Greece Hungary Iceland Ireland Italy Luxemburg The Netherlands Norway Poland Portugal Romania Spain Sweden Switzerland U.K. Yugoslavia U.S.S.R.

2100 656 (77) 2216 (85) 2458 (77) 243 (22) 12 734 (61) 153 4675 (78) 1673 (74) 5271 1888 (80) 2300 4562 5121 (62) 70 (74) 1143 (84) 155 5466 (80) 3.0 5231 (90) 11 000 367 1600 11 754 (75) 6400 320 000 (89)

Temporary annual grass

Feed root crops

35 9 171 326 2665 735 107 106 300 82 587 300 8 35 376 288

-

(4) (0.3) (5) (30) (13)

18 16 18 132 305

(2) (5)

134 (2) 63 (3)

(3)

20 (1)

(4) (9) (3)

24 31 (0.4) 0.1 (0.1) 2 (0.1)

(4)

.

. 218 (4)

(2) (0.6) (1) (12) (2)

257 (4) . 88 (1)

899 1844 (12) 17 774 (5)

Green fodder from arable land (maize, clover, lucerne, etc.)

119 (1) 1714 {0.5)

143 366 555 397 5045

Total

(17) (14) (17) (36) (24)

852 2607 3202 1098 20 749

1086 (18) 406 (18) 371 (16)

6002 2248

2755 16 185 864 . 277 1891

{33.5) (17) (13) (12) (5)

(12)

21 752 (6)

2361 5173 8207 94 1365 6875 5814 15608 361 240

Percent area in parentheses. Sources: Eurostat, 1983; C.M.E.A., 1979; A. Kornher, personal communication, 1983.

can convert forage cellulose into utilisable nutrients through microbial fermentation, whereas simple-stomached animals are of course largely dependent on cereals/concentrates. Melville (1960) argued that the output of human food energy and protein from a hectare of land utilised by ruminants is only a fraction of the output which can be obtained in the form of direct-use crops such as cereals, and that, in view of the poor nutritional status of much of the world's population, land devoted to producing "luxury" feeds should be diverted to direct-use crops. Against this background it is relevant to investigate the extent to which forage areas could, if necessary, be diverted to direct-use food

16 crops. Areas devoted to feed grain are excluded since it is a plausible assumption that they are also suited to direct-use food crops.

E.E.C. region The Utilised Agricultural Area (UAA) of EEC-10 extends over 101.9 Mha, and comprises 49.3 Mha of arable land, 46.2 Mha permanent grassland and 6.0 Mha temporary grassland. In the arable category annual forage crops occupy 4.5 Mha with lucerne occupying 2.0 Mha. Since the land-use types, temporary grassland, annual forages and lucerne, have similar soil requirements to food crops, it may be inferred that 12.5 Mha could, if necessary, be diverted to direct-use food-crop production. It is notable that France alone accounts for 40% of the total area with this land-use option. A study of the land resource base of the EEC-10 (Lee, 1986) concluded that 30.6 Mha were well suited to cultivation, 26.7 Mha were suited, 48.5 Mha were moderately/poorly suited and 48.4 Mha were unsuited. While cultivation is feasible on the moderately/poorly suited category it must in practice be largely excluded from consideration for mechanised arable systems, and it was concluded that the land pool having viable arable land use options was limited to 57.0 Mha, classified as being well suited or suited to cultivation. It must, nevertheless, be concluded from the above figures that the permanent grassland areas in the main correspond with the lower arable suitability classes and would not therefore, have an alternative food-crop option.

East and South East Europe Eastern European diets are basically cereal-based, while Western European diets contain a large share of grassland products. In Eastern Europe grassland does not play an important role in ruminant production, the percentage UAA under grass is small, and relatively low yields suggest natural grassland farming and a general restriction of grassland to areas of poor suitability for arable use. The major grassland areas include the valleys and flood plains of rivers and hill/mountain zones such as the Carpathians, the Stara Planina and Rhodope foothills and the Transylvanian Alps. Grains form the most significant part of the feed resources, ranging from 30-40% of the forages and feed resources in Romania and Poland to 60-70% in Hungary and Bulgaria. Areas devoted to feed grains would also be adapted for direct-use food-crop production as would the non-grain fodder-crop area (fodder roots, forage/green maize and grass crops). The latter category extends over 9.2 Mha in the Centrally Planned Economy (CPE) zone (Yugoslavia included).

17 GRASS

General The best index of the impact of grassland utilisation in a country is the extent of the agricultural area that is devoted to grassland (Table III). As stated earlier, there are pronounced geographic differences in that parameter. Another important factor is pasture composition. For example, the EEC-10 grassland area of 53.0 Mha (50% UAA) includes 6.0 Mha of temporary grassland, with France and the U.K. accounting for the major component, and it is notable that a high proportion of temporary pastures also occur in Denmark. These pastures are most responsive to management inputs and their yield performance is superior to that of permanent grassland.

Agro-ecologic variation Because of considerable variation in agro-ecological conditions, grassland productivity may show considerable spatial variation in Europe. It is appropriate, therefore, to examine these variations. For this purpose, Europe may be divided into five major geographic/climatic regions ( Papadakis, 1966) ( Fig. 1 and Table III) which are described below. (i) North West and West Europe: France (North West); Benelux; Denmark; U.K.; Ireland. Cool marine-cool temperate climate dominant. ( ii ) Central Europe: Federal Republic of Germany ( F.R.G. ) ; German Democratic Republic (G.D.R.); Poland; Czechoslovakia; Hungary; Switzerland; Austria. Cool temperate climate dominant in the north, warm continental-steppe dominant in the south and Taiga in the high alps. ( iii ) South East Europe: Bulgaria; Romania; Yugoslavia. Steppe climate dominant in lowlands and semi-warm continental-cool temperate dominant in mountain zones. (iv) Mediterranean Europe: Portugal; Spain; Italy; France (South); Greece; Yugoslavia (coastal). Mediterranean climate dominant. (v) Northern Europe and European U.S.S.R.: Fennoscandia; Iceland; U.S.S.R. Cool/cold temperate climate dominant in Fennoscandia and the Baltic Republics and cold continental dominant in the U.S.S.R.

Actual production in Europe Management inputs are highly significant in grassland production; these include the level of fertilizer input, the grazing system and the application of irrigation. Owing to possible intra-country variation in ecological factors it is difficult to apply reliable national pasture output figures. Nevertheless, based on a comprehensive examination (Lee, 1983 ) Table IV sets out such acom-

18

10.2

10.1

__

6%,

,p

~s

II 0

7.7

7-2 ( ~ )

7.6

7"6

9"2

7.5

6'2

~

6.8

%1

Fig. 1. C l i m a t i c R e g i o n s . 6 = M e d i t e r r a n e a n : 6.1 = s u b t r o p i c a l m e d i t e r r a n e a n ; 6.2 = m a r i n e m e d i t e r r a n e a n ; 6.5 = t e m p e r a t e m e d i t e r r a n e a n ; 6.6 = cold m e d i t e r r a n e a n ; 6.7 = c o n t i n e n t a l m e d i t e r r a nean; 6.8=semi-arid subtropical mediterranean; 6.9=continental semi-arid mediterranean. 7 = M a r i n e : 7.1 = w a r m m a r i n e ; 7.2 = cool m a r i n e ; 7.3 = cold m a r i n e ; 7.5 = w a r m t e m p e r a t e ; 7.6 = cool t e m p e r a t e ; 7.7 = cold t e m p e r a t e . 8 = C o n t i n e n t a l : 8.2 = s e m i - w a r m c o n t i n e n t a l ; 8.3 = cold c o n t i n e n t a l . 9 = Steppe: 9.1 -- w a r m s t e p p e ; 9.2 = s e m i - w a r m s t e p p e ; 9.4 = t e m p e r a t e s t e p p e . 10 = Polar: 10.1 = taiga; 10.2 = t u n d r a ; 1 0 . 4 - - i c e cap; 10.5 = a l p i n e . Source: P a p a d a k i s , 1966.

19 TABLE III Extent of grassland by the major regions and share of grassland in UAA Region

Grassland (106 ha)

Percentage of UAA

North West and West Europe France The Netherlands Belgium Luxemburg Denmark U.K. Ireland Total

15.4 1.2 0.7 0.1 0.6 13.6 5.1 36.7

49 59 49 60 21 73 90 59

Central Europe F.R.G. G.D.R. Poland Czechoslovakia Hungary Switzerland Austria Total

4.8 1.8 5.7 2.6 2.0 1.6 2.1 20.6

40 22 33 25 20 80 56 34

South East Europe Bulgaria Romania Yugoslavia Total

2.2 5.4 6.4 14.0

30 30 44 36

Mediterranean Portugal Spain Italy Greece Total

3.0 11.0 5.4 5.6 25.0

50 35 30 60 39

1.3 0.5 0.9 2.3 5.0

36 52 35 99 53

101.3 337.8

44 61

439.1

54

Northern Europe Sweden Norway Finland Ireland Total Europe U.S.S.R. Europe and U.S.S.R., total

For some countries outside the E.E.C. temporary grassland may be excluded. Sources: Eurostat, 1981; F.A.O., 1979; A. Kornher, personal communication, 1983.

20 TABLE IV Estimated production from grassland and level of N application (1981) Average pasture/hay yield ( D M kg h a - ' ) North West and West Europe France 4500 The Netherlands 12 000 Belgium 1 6000-12 000 Denmark 10 000 U.K. 5000-6000 Ireland 6000-7000 Central Europe F.R.G. G.D.R. Poland Czechoslovakia Hungary Switzerland Austria

South East Europe Bulgaria Romania Yugoslavia Mediterranean Portugal Spain Italy Greece Northern Europe Sweden Norway Finland Iceland

Average N application ( kg ha - ~) 30 265 50-300 150-250 39-167 50

5870 3270 3000 2180-3000 1600 2000-9000 (Hill) 2400-4500 (Hill)

100 -

500-2500 (Pasture) 1500-6000 (Hay) 2000 + 2700-5400

300-2000 1000 (South) 1000 (Pasture) 2200-7360 (Hay) 2000

1500-3000 5000 1500-3000 3830 4000

20 20 20 20

(North) (South) (North) (Hay) (Hay)

'C.V. Boucqu~, personal communication, 1986. Source: Lee, 1983.

parison of pasture yields. There is a lack of comparative data for the level of input of nitrogen, which is the major grass growth-promoting nutrient. Clearly, highest yields occur in the north-west and west, and the lowest yields in the Mediterranean, Northern Fennoscandia and in the south-east, with the central region recording intermediate levels of yields. However, there may be pronounced intra-country variation e.g. Southern Fennoscandia and lowland

21 areas of Switzerland/Austria compared with the Alpine zone. Although there is only scant information and a lack of comparative data, it may be concluded that the level of nitrogen application is highest in North Western and Western Europe. In Eastern European countries, such as Poland and Czechoslovakia, much of the grassland area comprises natural meadows and haylands receiving comparatively low levels of fertilizer application.

North West and West Europe Grassland output at farm level in the U.K., France, the F.R.G. and Ireland is 4500-8000 kg DM ha -1, whereas in Benelux and Denmark it is 8000-12 000 kg ha-1, which reflects intensive pasture use at farm level. Rainfall and the available water capacity of the soil are major yield determinants, with output in the U.K., for example, ranging from 6000-14 000 kg DM ha -1 under intensive fertilisation. Milk outputs of 9000 1 h a - 1 and beef outputs of 950 kg h a are attainable from the better grasslands of the region. Central Europe In the Central European zone of Poland and the German Democratic Republic, grasslands are concentrated along the valleys and flood plains of rivers as well as in the Ore-Sudeten-Carpathian hill and mountain zones of the south. In the North German Plain and the Vistula Valley, intensively fertilised grassland has a yield potential of 7000-9000 kg DM ha-1 in the sandy areas, and up to 11 000 kg ha -1 in high-fertility areas. Under farm conditions in Poland grassland output ranges from 1700-6500 kg DM ha -1 in the river valleys, depending on available moisture. In the montane/submontane zones of Switzerland, Austria, Poland, the F.R.G. and Czechoslovakia output declines from 9500 kg DM ha -1 at 400-600 m to 1500-2000 kg DM ha -1 at 1500-2200 m. In lowland Czechoslovakia productive capacity of natural grassland is about 9500 kg DM h a - 1, whereas in the arable lowland of Switzerland clover leys are capable of outputs as high as 14 000 kg DM h a - 1. Under the steppe conditions of the Hungarian Plain moisture stress is a major limitation, with seeded legume/grass swards showing a 100% response to irrigation compared with 35% in the North German Plain. South East Europe Grassland occurs largely in the montane and submontane zones, such as the Carpathians and Transylvanian Alps in Romania, the Stara Planina and the Rhodope in Bulgaria and the extensive mountain and hill regions of Yugoslavia. In Romania, unfertilised permanent pastures yield about 2000 kg DM h a - 1. Yields of 3000-4500 kg DM h a - 1 are attainable from fertilised Bromus inermis and Festuca/Agrostis swards, compared with seeded pasture yields of 9500 kg DM ha -1. In Bulgaria, meadow yields range from 1500-6000 kg DM h a - 1, depending on meadow type and altitude. In the better areas ( < 500 m)

22

of Croatia in Yugoslavia, rainfed yields in excess of 10 000 kg DM ha-1 have been achieved from natural meadows. Mediterranean The permanent grazings of the Mediterranean zone are subject to severe moisture stress with annual production being limited to about 1000 kg DM ha-1 and with stocking rates ranging from the equivalent of 0.25 livestock units (LU) ha-1 in Portugal to as little as 0.05 LU ha-1 in the poorer forest ranges of Greece. However, improved technology is capable of raising production levels to about 3500 kg DM h a - 1. In this ecological zone, irrigated legume and legume/grass swards are capable of outputs of 20 000 kg DM h a - 1. Similarly in the steppe regions of Hungary, Romania, Bulgaria and South U.S.S.R., irrigated swards yield 13 000-17 000 kg DM h a - 1. Northern Europe Temporary pastures are an important component of Southern Fennoscandian grassland where the average yield of good grass/clover leys is 8000 kg DM ha-1. Despite the brevity of the growing season, photoperiodically long-day grasses are capable of outputs of 5000-7000 kg DM h a - 1, even within the Arctic Circle. High nitrogen exacerbates winter damage to swards with a depressing effect on yields. In Western Scandinavia, the disadvantages of a northern latitude are modified by the favourable Gulf Stream influence. In the Baltic and forest zones of the U.S.S.R., intensively fertilised (200 kg N h a - 1) pastures have a yield capacity of 6000-9000 kg DM ha-1. In the Ukraine yields range from 6000 kg (Carpathians) to 2000 kg DM h a - 1 (steppe zone). Importance of grass as an animal feed

The estimated share of grassland in animal feed consumption in E.E.C. and Eastern European countries is compared in Table V. For EEC-9, grassland is taken to be synonymous with perennial fodder crops comprising meadows, pastures, clover, lucerne and other perennial fodder crops. Clearly the reliance of Eastern European countries on grassland is substantially less than in E.E.C. countries. When the data from Table V are compared with Table III (share of grassland in UAA) a general correlation exists: a higher share of grass in animal diets coincides with a higher share of grassland in the UAA. There are notable exceptions such as Benelux, which although characterised by the highest pasture yields in Europe, has a comparatively low share in animal feed. This is attributed to high levels of concentrate feeding to ruminants and, notably, to the high yielding dairy herd in that region. Obviously the composition of feed resources differs from country to country in accordance with environmental conditions, farming systems and production technology. Lowland countries such as Poland, the G.D.R. and Hungary have,

23 TABLE V Estimated share of grassland in total ruminant feed composition in E.E.C. countries and in Eastern European countries Pasture

Hay

Silage

Total

EEC-9 Countries (French feed units ( % ) ) 1 Belgium/Luxemburg 8.4 Denmark 32.3 F.R.G. 26.0 France 30.9 Ireland 62.6 Italy 8.4 The Netherlands 26.7 U.K. 59.3

20.2 3.9 15.8 23.4 10.2 27.3 6.6 13.2

22.4 10.8 18.2 16.7 24.1 17.3 20.7 10.5

51 47 60 71 97 53 54 83

Eastern Europe (grain units ( % ) ) Bulgaria Czechoslovakia G.D.R. Hungary Poland Romania Yugoslavia U.S.S.R.

20.2 50.9 39.6 36.1 41.1 38.7 42.2 22.4

13.8 8.1 10.4 8.9 9.9 14.3 23.8 36.6

34 59 50 45 51 53 66 59

Sources: Lee, 1983; Eurostat, 1980; F.A.O., 1979; van Dijk and Hoogervorst, 1984. 1Feed unit system based on Leroy's system of feed equivalents is the system still in use by Eurostat (Statistical Office of the European Communities).

in general, a smaller percentage of pastures than countries with a more varied relief such as Bulgaria and Yugoslavia.

Contribution to human food supply The value of grassland is determined by its contribution to food supply. Local and foreign demand for foodstuffs and aspects of farm management determine the extent to which grassland potential is exploited (van Dijk and Hoogervorst, 1984). By examining the role of milk, beef, veal, mutton, lamb and goat meat in the domestic food supply in various countries, the relative importance of consumer demand for future grassland developments can be illustrated (Table VI ). The data in Table VI show that grassland products are more significant in diets in E.E.C. countries than in Eastern European countries. In the latter, cereal consumption is relatively high and beef consumption is fairly low. Other kinds of meat (or meat products) seem to compensate for this. In general, it can be concluded that Eastern European (C.P.E.) diets are basi-

24 TABLE VI Per capita annual energyintake from various food categoriesproducedby ruminants in 1978 (kJ) Food category All meat and meat products Beef Sheep and goat Milk and milk products Cereals Milk {products)/ cereals ( %) Beef/cereals (%)

Bulgaria C.S.S.R. G.D.R. Hungary

Poland

Romania

EC-9

588 104 54

796 221 8

825 187 8

667 121 4

675 175 4

525 96 21

775 475 25

450 2184

488 1474

838 1292

325 1634

283 1663

442 2189

776 1130

21 5

33 15

65 15

20 7

17 11

20 4

69 42

Source: van Dijk and Hoogervorst, 1984. cally cereal based, while Western European diets contain a larger share of grassland products. Since virtually all countries are now self-sufficient in these products it can also be concluded t h a t grassland production plays a more important role in the domestic food supply in Western European countries. In addition to domestic demands for grassland products, countries may also be faced with foreign sources of demand. In centrally planned economies exports may also be the result of political efforts aimed at pursuing a favourable balance of payment position with western countries. Self-sufficiency ratios (SSRs) for milk show t h a t Mediterranean countries and the U.K. are importers of milk and dairy products. These imports range from 10 to 27% of domestic utilisation. European C.P.E. countries have self-sufficiency ratios ranging from 99 to 109; in all other European countries milk production by far exceeds domestic h u m a n consumption (E.A.A.P., 1982). For beef and veal the differences in Europe are much bigger. Some countries are large exporters (Ireland's SSR was 613% in 1978), while others have to import large quantities ( Greece 52%; Italy 39% ) of domestic consumption (E.A.A.P., 1982 ). The Eastern European countries as a group are self-sufficient, with the C.S.S.R. and the G.D.R. as net importing countries, and Hungary as an important net exporter. Bulgaria and Romania are important exporters of m u t t o n (O.E.C.D., 1981-1982). Thus in various European countries, and most notably in Denmark, Ireland, The Netherlands, Hungary, Poland and Romania, grassland production has important implications for the national economy via its contribution to foreign trade. (van Dijk and Hoogervorst, 1984). Grassland products can potentially be based on grass only, but in practice there is a wide variety of diets for ruminants. Therefore, the techniques and economies of production determine whether, how and to what extent grassland is used to produce grassland products (van Dijk and Hoogervorst, 1984).

25

Production potential Lee (1978) constructed a land-capability map for forage production for the continent of Europe, and more recently Lee (1984) compiled a draft soil-suitability map (1:1 million) for grassland for the EEC-10 countries. Ecological factors such as precipitation deficits, temperature regimes and soil/land conditions were taken into account in the assessment. In general, land north of the 60th parallel (Scandinavia) and south of the 44th parallel (Mediterranean countries) are ill-suited for grassland production. The most favourable conditions are present in North Western and Western Europe, Ireland, the U.K., Benelux, North West France and Bavaria. In the predominantly hilly areas, where a high proportion of the UAA is devoted to grassland, such as the Central European highlands, Alpine Foreland and Massif Central, grassland production/utilisation is restricted by soil conditions such as stoniness, rockiness and accessibility. Throughout much of the remainder of Europe moisture deficit is a major factor restricting yields, e.g. in the lowland Balkans and the North G e r m a n and Polish plains. From an economic standpoint, it is important to determine the extent to which different countries exploit their grassland resources. Table VII is an inter-country comparison of suitability for grassland with the proportion of grassland in the UAA. In general, those countries which are well suited ( Class A) have a relatively high proportion of their UAA under grassland, and TABLE VII Suitability for grassland, Classes A-E 1. Yieldpotential (103kg DM ha -1 ) in parentheses Grassland (% of UAA)

Class A (10-12)

65-100

Ireland U.K. (W)

35-65

The Netherlands Belgium France (NW)

'-

12

C~

_c:

E 23

¢-

20 ~-

:

L.

193/,1938

19/,6- 1951- 1956- 1961- 1966- 1971- 1976- 1981- 1986- 1991 1996 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 :2000

"10 O t._ 13..

Fig. 13. Oats area, yield, production and utilization data for Europe excluding U.S.S.R. (compiled by the author).

/~

22

1

21 (,t) r... 20

/I /

19 r'O

:,182 ~5®

~ 2

//

L

1~

16 C

-

°

'-

12 C O

50 kg Sows

0-5 2.5-5 4-5 4-5

Ruminant compounds Calf Dairy Beef Sheep, goat

0 2.5-5 5 5

Fish Salmon, trout Carp

15 18

Blood meal

Poultry by-product meal

2 2 2 2 1 2 2 2 2 2 2

2-2.5 2-5 5 0 2-2.5 4-7.5 0 5 5 2 4-5

0 0-1 0-2 0-2

0 0 2.5 2.5

0 0-2.5 0-2.5 0-2.5

0 2.5-5 2.5-5 2.5-5

0 2.5 2.5 2.5

0 2.5-5 2.5-5 0-5

2 2

15 18-20

5 5

N.B. Tallow may be included in poultry diets at up to 4-6% and in dairy compounds at up to 2-3%; more usually fat blends are used in which tallow may be a component depending on price. Economic constraints and physical ability to include tallow usually limit inclusion of tallow.

188 TABLE XVIII Minimum and maximum recommended levels of fish-meal inclusion 1 Diet

Minimum inclusion 2 (%)

Maximum inclusion ( % ) 2 Low-fat fish meal (10%)

In poultry diets 3 Broiler starter 4 15 10 8 Broiler grower 4 15 8 6 Broiler finisher 2 15 8 6 Turkey starter 6 15 12 9 Turkey grower 4 15 10 7 Turkey finisher 1 8 5 3 Hen layer 2 15 15 15 Hen breeder 4 15 15 15 In pig diets 4 Weaner (3 weeks, 20 kg) 5 No limit 12 12 Grower (20-50 kg) 2 12 8 5 Finisher ( > 50 kg) 1 10 4 3 Breeding and lactating 4 No limit 12 12 In fish diets (%) 30 60 60 60 In cattle dietss,particularly those based on grass silage (g head-' day- ') Young growing cattle 200 250 250 250 Store and finishing cattle gaining 200 250 250 250 < 0.7 kg d a y - 1 High yielding dairy cows 500 750 750 750 In sheep diets 6 based on cereals or roots or grass silage or alkali-treated straw (g head- ' day- ' ) Growing lambs 50 100 100 100 Late pregnancy 50 150 150 150 Lactating ewes, 120 390 390 first 6 weeks 1Fish meal need not be included but economic responses have been obtained, when suggested minimum inclusion levels have been used under certain circumstances. 2Maximum inclusion levels indicate levels above which problems of unacceptable taint or flavour in meat and milk are certain to exist. Practical inclusion rates in most European countries are much lower. ~Data adapted from Barlow and Windsor (1983). 4Data from Pike (1987). 5Data from Miller and Pike (1985; 1987). 6Data from Orskov (1982); Marchment and Miller (1983, 1984); Gonzalez et al. (1984); Yilala and Bryant (1985) ; Hassan and Bryant (1986a, b, c) ; Robinson (1987).

petitive where animal production rates are greatest and the nutrient density r e q u i r e d is c o r r e s p o n d i n g l y h i g h a s i n s t a r t e r d i e t s f o r p o u l t r y a n d p i g s . A n i m a l products are also used where the digestive system of the animal requires highly-

189

digestible feed or is not well adapted to deal with vegetable cell wall structures, as in the pre-ruminant calf, mink and fish. The low allergenicity of milk byproducts and fish meal compared with vegetable products such as soya is further reason for their inclusion in diets for early-weaned pigs (Newby et al., 1984). Reduced palatability and constraints on calcium and phosphorus content limit the inclusion of meat and bone meal in diets. Poor digestibility and aminoacid balance restrict the inclusion of hydrolysed feather meal. The dark colour and restricted market supplies of blood meal limit its inclusion rate. The inclusion of animal fat or of fat blends in poultry diets is limited primarily by the physical effect on pellet quality. For ruminants, the adverse effect of low melting-point fats on rumen fermentation limits inclusion.

By-products from the fish meal and oil industry Minimum inclusion rates are used to force fish meal into least-cost diets where the additional cost of so doing is more than offset by an improvement in feed conversion beyond that expected on the basis of the current nutrient analyses of feeds. This applies particularly to diets for poultry (Pike, 1975) and for high-yielding ruminants (Miller and Pike, 1985, 1987 ). The high content of UDP with a good amino-acid balance in fish meals make them valuable supplements in ruminant diets, especially at times of peak need and when the basal-energy ingredients supply little UDP. Maximum constraints for fish meal relate to problems of taint in the meat of monogastrics if the fish-oil content of the diet exceeds 0.4-1.0% depending on animal species, stage of growth, degree of polyunsaturation of the fish oil and amount of other dietary fats or oils. Care needs to be taken to ensure that fish-acid oil is not included in a fat blend to be fed in a diet where the maximum amount of fish meal is used, otherwise the limit on fish oil will be exceeded and the risk of taint greatly increased. There are differences between populations in perception of what is a desirable or an undesirable flavour. For this reason, the suggested maxima in Table XVIII are guidelines only, which may be varied according to local preferences. Recent evidence of the benefits of including n-3 fatty acids in the human diet to modulate eicosanoid metabolism with consequent effects upon blood clotting, blood pressure, cardiovascular and auto-immune diseases (Lands, 1986) may result in a fishy flavour being more acceptable and consumption of pigs and poultry fed on fish meal or with added fish oil as being one method of enhancing intake of these n-3 fatty acids in a palatable form. For lactating cows, the daily intake of fish oil should be less than 100 g, otherwise the fat content of the milk is depressed. Maximum levels for cattle and sheep reflect amounts shown to give production responses when given as the main source of supplementary UDP. Practical amounts will depend on availability and relative cost of alternative sources of UDP.

190

Laboratory tests of protein quality in animal by-products Protein quality may easily be adversely affected by the processing of animal by-products. Laboratory methods to assess protein quality in these by-products are therefore very important. These methods include determination of pepsin digestibility (A.O.A.C., 1975), dilute pepsin digestibility (Olley and Pirie, 1966 ), rate of digestion by multi-enzymes ( Pedersen and Eggum, 1983 ), FDNB-reactive lysine (Roach et al., 1967; Carpenter and Booth, 1973) and dye-binding lysine (Hurrell et al., 1979). The use and limitations of some of these methods as applied to animal by-products have been discussed by Carpenter and Booth (1973), Waibel et al. (1977), Barlow et al. (1984), Opstvedt (1984a) and Batterham et al. (1986a, b ). It should be noted that the A.O.A.C. pepsin-digestibility method uses 100 times as much pepsin as the dilute method. Consequently it does not discriminate adequately between samples of moderate to good quality. DEVELOPMENTS AND FUTURE PRODUCTS FROM BY-PRODUCTS OF THE ANIMAL INDUSTRY

Feed potential of animal excreta Increased livestock production and increased intensification of production has given rise to difficulty in achieving satisfactory and economic disposal of manure without causing environmental pollution. For example, legislation is to be introduced in Holland from 1988 restricting the amount of waste, measured in terms of phosphate content, applied to land, so as to control pollution of water supplies. As a consequence, extensive research has been carried out to determine whether processed animal manures might have potential as an animal feed. The results, so far, have shown that artificially-dried poultry manure is useful as a nitrogen and phosphorus supplement for ruminant diets. The high uric acid content is a better source of non-protein nitrogen than synthetic TABLE XIX Chemical composition and feeding value of wastes from livestock

Manure, cow Manure, pig Manure, poultry Rumencontents

DM kg -1

XP (gkg -1 DM)

XL (gkg -~ DM)

XF (gkg -1 DM)

Digestibility of OM (%)

161 230 225 110

186 200 350 164

50 60 25 25

238 200 125 301

c. 25 c. 50 60-70 35-45

Steg (1979) Fontenot (1983) Steg (1979) Steg (1976)

191

urea, as it degrades more slowly and provides the rumen micro-organisms with a steadier supply of ammonia. Manure from caged birds is better than that from birds housed in deep-litter systems, where indigestible litter reduces the energy value of the resultant dried feed. Up to 20-30% of dried poultry manure has been successfully included in compound feeds fed to dairy cows, beef cattle and sheep (A.D.A.S., 1975; de Boer, 1980) and up to 25% in complete diets for intensively-reared beef cattle (Oliphant, 1974; Tagari, 1976). Problems of control of toxic contaminants from the use of chemically-treated wood shavings as litter and from medication of the poultry feed exist. Moreover, fear of causing a consumer aversion to meat from animals fed in this way has prevented any acceptance of dried poultry manure as an animal feed. Table XIX shows some data on the chemical composition and feeding value of various wastes arising from livestock husbandry on farms. More detailed analyses on dried poultry manure are given in A.D.A.S. (1975).

Potential products from the dairy industry The dairy industry has already developed a range of new methods, ultrafiltration, microfiltration, ion-exchange chromatography and electrophoresis, for the separation of principally the casein and whey protein fractions to provide a new range of products for the food, dietetic and pharmacological industries ( Maubois, 1986). The production of so called zero-milk replacers for calves, based on isolated whey proteins with some vegetable proteins, is already established. Immunoglobulins can be separated from whey and used as a substitute for, or to enhance the protective effects of colostrum. While the new processes will be engineered to produce high-value products, undoubtedly new by-product materials will become available to the animal-feed industry. For example, separation of whey proteins by ultrafiltration produces a residual permeate consisting primarily of lactose and minerals. Development of economic methods for using the permeate in animal feed will markedly affect the economics of preparation of the isolated whey products. However, in the E.E.C. area, current legislation needs to be modified in order to allow the economic use of the new by-products in animal feeds and thereby facilitate the development of novel dairy products for human consumption.

Potential products from the rendering industry Although there are advantages in producing high-energy diets, there are physical constraints on the amount of liquid fat that can be included in diets without reducing pellet quality. Dry-fat powders have advantages in ease of handling and facilitating higher fat-incorporation levels in pelleted diets. New processes, in which protein and fat are emulsified together prior to drying, produce dry fat supplements with good pelleting characteristics. Blood or meat

192

scraps can provide a suitable source of protein and animal scraps tallow as the fat source. Improved meat and bone meals can be manufactured by better control of processing temperatures to avoid protein damage and the use of enzymes to bring about partial hydrolysis of the more indigestible proteins. Special products suitable for the expanding fish-farming market are likely to be developed. Techniques for the extraction of immunoglobulins from pig blood obtained from the slaughterhouse have been developed. Initial trials show the product can be fed to piglets and reduce mortality. Heated blood is known to be resistant to microbial degradation in the rumen. Use has been made of this property to coat other proteins, amino acids and fats in an attempt to protect these nutrients from degradation in the rumen.

Potential products from the fish meal and oil industry Reference has already been made to a range of special-product fish meals which have recently appeared on the market (Pike, 1987). Their importance is likely to increase. Already, in 1986 they accounted for 45% of Norwegian fish meal production (S.S.F., 1987). Continuing research is expected to lead to further refinement of products specifically tailored for culture of prawns and salmon fry, for rearing salmon smolts, early weaned pigs and mink, for inclusion in milk-replacers and for feeding to ruminants (Gulbrandsen, 1986). In addition, every effort is being made to increase the production of food-grade products. These developments are expected to lead to reduced availability of the normal fish meal for feeding to pigs and poultry.

REFERENCES A.O.A.C., 1975. Pepsin digestibility of animal protein feeds - - official final action. Official Methods of Analysis, 12th edn. Association of Official Analytical Chemists, Washington, DC, pp. 133-135. A.D.A.S., 1975. Dried poultry manure as a feedingstuff. Agricultural Development and Advisory Service, Short Term Leaflet 175. Ministry of Agriculture, Fisheries and Food, London, 5 pp. Anderson, J.O. and Warnick, R.E., 1970. Studies of the need for supplemental biotin in chick rations. Poult. Sci., 49: 569-578. Atkinson, R.E., 1985. Feed Grade Animal Fats (FGAF) in Feeds. In: R.E. Atkinson (Editor), Feed Grade Animal Fats (FGAF) in Feeds. The National Renderers Association in cooperation with the U.S. Dept. Agric., Des Plaines, IL, pp. 1-16. Barlow, S.M. and Windsor, M.L., 1983. Fishery by-products. In: Handbook of Nutritional Supplements, Vol II, pp. 253-272. Barlow, S.M., Pike, I.H. and Nixon, F., 1979. Choline content of fish meals from various origins. J. Sci. Food Agric., 30: 89-92. Barlow, S.M., Collier, G.S., Juritz, J.M., Burt, J.M., Opstvedt, J. and Miller, E.L., 1984. Chemical and biological assay procedures for lysine in fish meals. J. Sci. Food Agric., 35: 154-164. Batterham, E.S., Lowe, R.F., Darnell, R.E. and Major, E.J., 1986a. Availability of lysine in meat

193 meal, meat and bone meal and blood meal as determined by the slope-ratio assay with growing pigs, rats and chicks and by chemical techniques. Br. J. Nutr., 55: 427-440. Batterham, E.S., Darnell, R.E., Herbert, L.S. and Major, E.J., 1986b. Effect of pressure and temperature on the availability of lysine in meat and bone meal as determined by slope-ratio assays with growing pigs, rats and chicks and by chemical techniques. Br. J. Nutr., 55: 441-453. Boucqu~, Ch.V. and Fiems, L.O., 1988. Feedstuffs. 4. Vegetable by-products of agro-industrial origin. Livest. Prod. Sci., 19: 97-135. Buraczewska, L., Lachowicz, J. and Zebrowska, T., 1979. Kryl antarktyczny, przetworstwo i wykorzystanie. Stud. Mater., Ser. S, No. 1,146-153. Carpenter, K.J. and Booth, V.M., 1973. Damage to lysine in food processing: its measurement and its significance. Nutr. Abstr. Rev., 43: 423-451. Cuppett, S.L. and Soares, J.H., 1972. The metabolizable energy values and digestibilities of menhaden fish meal, fish solubles, and fish oils. Poult. Sci., 51: 2078-2083. De Boer, F., 1980. Dried poultry manure (DPM) in Dutch ruminant feeding. In: Livestock Waste: A Renewable Resource. 4th International Symposium on Livestock Wastes. Amarillo, U.S.A. A.S.A.E., St. Joseph, Michigan, pp. 22-26, 30. Dierick, N.A., Vervaeke, I.J., Decuypere, J.A., van de Heyde H. and Henderickx, H.K., 1987. Correlation of ileal and fecal digested protein and organic matter to production performances in growing pigs. Proc. 5th Int. Symp. on Protein Metabolism and Nutrition, Rostock (in press). Digest of Feed Facts and Figures, 1987/88 edn. HGM Publications, Baslow, U.K., 30 pp. F.A.O., 1985. Production Yearbook, Vol. 39. Food and Agricultural Organisation, Rome. 330 pp. F.A.O., 1986. The production of Fish Meal and Oil. Fisheries Technical Paper, 142, Food and Agricultural Organisation, Rome, 63 pp. Fontenot, J.P., 1983. Utilisation of animal wastes by feeding: special emphasis on United States of America. In: E.H. Ketelaars and S. Boer Iwema (Editors), Animals as Waste Converters. Pudoc, Wageningen, pp. 12-22. Frigg, M., 1984. Available biotin content of various feed ingredients. Poult. Sci., 63: 750-753. Gabrielsen, B.O. and Opstvedt, J., 1980. Availability of selenium in fish meal in comparison with soybean meal, corn gluten meal and selenomethionine relative to selenium in sodium selenite for restoring glutathione peroxidase activity in selenium-depleted chicks. J. Nutr., 110: 1096-1100. Gonzalez, J.S., Robinson, J.J. and McHattie, I., 1984. The effect of level of feeding on the response of lactating ewes to dietary supplements of fish meal. Anim. Prod., 40: 39-45. Gulbrandsen, K.E., 1986. Special qualities offish meal in feed for mink and fish. Proceedings 26th Annual I.A.F.M.M. Conference. International Association of Fish Meal Manufacturers, Potters Bar, U.K., pp. 87-93. Hassan, S.A. and Bryant, M.J., 1986a. The response of store lambs to protein supplementation of a roughage-based diet. Anim. Prod., 42: 73-79. Hassan, S.A. and Bryant, M.J., 1986b. The response of store lambs to dietary supplements of fish meal. 1. Effects of forage-to-concentrate ratio. Anim. Prod., 42: 223-232. Hassan, S.A. and Bryant, M.J., 1986c. The response of store lambs to dietary supplements of fish meal. 2. Effects of level of feeding. Anim. Prod., 42: 233-240. Hurrell, R.F., Lerman, P. and Carpenter, K.J., 1979. Reactive lysine in foodstuffs as measured by a rapid dye-binding procedure. J. Food Sci., 44: 1221-1231. Jorgensen, H., Sauer, W.C. and Thacker, P.A., 1984. Amino acid availabilities in soybean meal, sunflower meal, fish meal and meat and bone meal fed to growing pigs. J. Anim. Sci., 58: 926-934. Jorgensen, J.N., Fernandez, J.A., Jorgensen, H.H. and Just, A., 1985. Anatomical and chemical composition of female pigs and barrows of Danish Landrace, related to nutrition. Z. Tierphysiol., Tierernaehr. Futtermittelk., 51: 252-263.

194 Just, A., Fernandez, J.A. and Jorgensen, H., 1982. Kodbenmels vaerdi til svin (The value of meat and bone meal for pigs.) Beret. Statens Husdyrbrugsfor., No. 525, pp. 1-52. Lands, W.E.M., 1986. Fish and Human Health. Academic Press, 170 pp. Lowe, S. and Howells, D., 1985. Fats for Feed; a suppliers view. In: National Renderers Association, Des Maines, IL. NRA Bull., No. 769, pp. 2-5. Marchment, S.M. and Miller, E.L., 1983. The response of store lambs to protein supplementation of a low quality diet. Anim. Prod., 36: 508. Marchment, S.M. and Miller, E.L., 1984. The response of store lambs to protein supplementation of alkali-treated straw-based diets. Anim. Prod., 38: 522. Marchment, S.M. and Miller, E.L., 1985. Voluntary food intake and growth responses in store lambs given protein supplements to grass silage. Proc. Nutr. Soc., 44: 47A. Maubois, J.L., 1986. Separation, extraction and fractionation of milk protein components. In: W.F. Raymond and P. Larvor (Editors), Alternative Uses of Agricultural Surpluses, Elsevier, Barking, U.K., pp. 77-85. Mehrez, A.Z., Orskov, E.R. and Opstvedt, J., 1980. Processing factors affecting degradability of fish meal in the rumen. J. Anim. Sci., 50: 737-744. Miller, E.L. and Pike, I.H., 1985. Milk quotas - - new feeding strategies to reduce milk production costs: Use of fish meal to improve feed efficiency and reduce feeding costs. International Association of Fish Meal Manufacturers, Potters Bar, U.K., pp. 1-24. Miller, E.L. and Pike, I.H., 1987. Feeding for profitable beef production: Use of fish meal to improve feed efficiency and reduce feeding costs. International Association of Fish Meal Manufacturers, Potters Bar, U.K., pp. 1-79. National Renderers Association, 1985. Pocket Information Manual and Exporters List. National Renderers Association Ltd., London. 94 pp. Newby, T.J., Miller, B.G., Stokes, C.R., Hampson, D. and Bourne, F.J., 1984. In: W. Haresign and D.J.A. Cole (Editors), Recent Advances in Animal Nutrition. Butterworths, London. pp. 49-59. Oliphant, J.M., 1974. Feeding dried poultry waste for intensive beef production. Anim. Prod., 18: 211-217. Olley, J. and Pirie, R., 1966. The pepsin digestibility method at low pepsin strengths. Fish. News Int., 5: No. 12. Opstvedt, J., 1973. Influence of residual lipids on the nutritive value of fish meal. IV. Effect of drying and storage on the energy value of the protein and lipid fractions of herring meal. Acta Agric. Scand., 23: 200-208. Opstvedt, J., 1976. Energy value of Norwegian herring fish meals for poultry. Feedstuffs. Miller Publishing Co., Minneapolis, 48(11 ) : 19, 22, 24. Opstvedt, J., 1984a. Use of chemical methods to assess quality of proteins in fish meal. Symposium on Use of Fish Meal in Animal Feeding, Budapest, Hungary. International Association of Fish Meal Manufacturers, Potters Bar, U.K. pp 8-27. Opstvedt, J., 1984b. Fish fats. In: J. Wiseman (Editor), Fats in Animal Nutrition. Butterworths, London, pp. 53-82. Opstvedt, J., Sobstad, G. and Hansen, P., 1978. Functional fish protein concentrate in milk replacers for calves. J. Dairy Sci., 61: 72-82. Orskov, E.R., 1982. Protein Nutrition in Ruminants. Academic Press, London 160 pp. Partridge, I.G., Low, A.G. and Matte, J.J., 1987. Double-low rapeseed meal for pigs: ileal apparent digestibility of amino acids in diets containing various proportions of rapeseed meal, fish meal and soya-bean meal. Anim. Prod., 44: 415-420. Pedersen, B. and Eggum, B.O., 1983. Prediction of protein digestibility by an in vitro enzymatic pH-stat procedure. Z. Tierphysiol., Tierernaehr. Futtermittelk., 49: 265-277. Pike, I.H., 1975. The role of fish meal in diets for poultry, Tech. Bull. No. 3. International Association of Fish Meal Manufacturers, Potters Bar, U.K., 40 pp.

195 Pike, I.H., 1987. Special product fish meals. The Feed Compounder, February 1987, pp. 13-14. Poppe, S., Meier, H. and Kiehn, J., 1987. The production and feed value of mixed protein silage. Proc. 5th Int. Sym. on Protein Metabolism and Nutrition, Rostock (in press). Potter, L.M., Shelton, J.R. and Parsons, C.M., 1980. The unidentified growth factor in menhaden fish meal. Poult. Sci., 59: 128-134. Roach, A.G., Sanderson, P. and Williams, D.R., 1967. Comparison of methods for the determination of available lysine value in animal and vegetable protein sources. J. Sci. Food Agric., 18: 274-278. Rendementsberekeningen 8601-8613 (1987); Produktschap voor Zuivel, Den Haag. Robinson, J.J., 1987. Energy and protein requirements of the ewe. In: W. Haresign and D.J.A. Cole (Editors), Recent Advances in Animal Nutrition - - 1987. Butterworths, London, pp. 187-204. Schiemann, R., Nehring, K., Hoffmann, L., Jentsch, W. and Chudy, A., 1971. Energetische Futterverwertung und Energienormen. VEB/DLV. Berlin. S~ve, B., Aumaitre, A., Jaubert, P. and Tord, P., 1978. Solubilization des proteines de poisson, supplementation en tryptophane et valeur alimentaire pour le porcelet. Ann. Zootech., 27: 423-438. Smits, B. and Steg, A., 1983. Flotation sludge from slaughterhouses as a feedstuff for pigs. In: E.H. Kebelaars and S. Boer Iwema (Editors), Animals as Waste Converters. Pudoc, Wageningen, pp. 101-103. S.S.F., 1987. Arsberetning S.S.F., 1986. Sildolje og Sildemelindustriens, Forsknings Institut, Bergen, Norway, 40 pp. Statistische Erhebungen und Sch~itzungen, 1987. Schweizerisches Bauernsekretariat, Brugg (CH), 64 Jahresn. Statistisch Jaaroverzicht 1985, 1986. Publ. Produktschap voor Zuivel, Den Haag. Steg, A., 1976. Onderzoek naar de voederwaarde van pensinhoud en flotatieslib. Vleesdistributie en Vleestechnologie, pp. 1-4. Steg, A., 1979. Hervoedering van mest. Syllabus PAO cursus "Veehouderij en Milieu". Sundstol, F., 1988. Feedstuffs. 5. Straw and other fibrous by-products. Livest. Prod. Sci., 19: 137-158. Tagari, H., Levy, D., Holzer, Z. and Ilan, D., 1976. Poultry litter for intensive beef production. Anim. Prod., 23: 317-327. Ten Have, P.J.W., 1983. De bruikbaarheid van flotatieslib van slachterijen als veevoeder. Rijks Agrarische Afvalwater Dienst (R.A.A.D.), Arnhem. Tilsch, K., GSrlich, L. and Ender, K., 1986. Mastleistung und Schlachtwert von Fleischrindbullen bei unterschiedlichem Schlachtalter. Arch. Tierz., 29: 253-259. United Kingdom, E.E.C., Dairy Facts and Figures, 1987. The Federation of United Kingdom Milk Marketing Boards, Thames Ditton, U.K. Uyttenboogaart, Th.G., 1979. Gewichtssamenstelling van slachtkuikens (Body composition of broilers.) Vleesdistributie en Vleestechnologie, 2: 36-39. Uyttenboogaart, Th.G., 1985. Gewichtssamenstelling van soepkippen. (Body composition of hens.) Vleesdistributie en Vleestechnologie, 3:30-31. Van der Honing, Y. and Alderman, G., 1988. Feed evaluation and nutritional requirements. 2. Ruminants. Livest. Prod. Sci., 19: 217-278. Veevoedertabel, 1979; 1986. Gegevens over voederwaarde, verteerbaarheid en samenstelling. Centraal Veevoeder Bureau in Nederland, Lelystad. Vogt, H., Krieg, R. and Harnisch, S., 1986. Versuche zur Beeinfltissung der SchlachtkSrperzusammensetzung von Broilern. Landwirtsch. Forsch., Kongressband 1984, pp. 577-596. Waibel, P.E., Cuperlovic, M., Hurrell, R.F. and Carpenter, K.J., 1977. Processing damage to lysine and other amino acids in the manufacture of blood meal. J. Agric. Food Chem., 25: 171-175.

196 Wainman, F.W. and Dewey, P.J.S., 1985. Metabolizable energy values: fish meals. Feedingstuffs Evaluation Unit Brief Report No. 18. The Rowett Research Institute, Aberdeen, 2 pp. Wainman, F.W. and Dewey, P.J.S., 1986. Metabolizable energy values: meat and bone meals. Feedingstuffs Evaluation Unit Brief Report No. 19, The Rowett Research Institute, Aberdeen, 2 pp. Whitehead, C.C., Armstrong, J.A. and Waddington, D., 1982. The determination of the availability to chicks of biotin in feed ingredients by a bioassay based on the response of blood pyruvate carboxylase (EC 6.4.1.1) activity. Br. J. Nutr., 48: 81-88. Yilala, K. and Bryant, M.J., 1985. The effects upon the intake and performance of store lambs of supplementing grass silage with barley, fish meal and rapeseed meal. Anim. Prod., 40:111-121.

Livestock Production Science, 19 (1988) 197-209

197

Elsevier SciencePublishers B.V., Amsterdam-- Printed in The Netherlands

II. 7. C o m p o u n d A n i m a l Feed and Feed A d d i t i v e s A.P. NAMUR,J. MORELand H. BICKEL

INTRODUCTION The feeding of compound feed and the use of feed additives for animal production in Europe have grown considerably since the beginning of this century, especially over recent decades. These were developed by independent national and international companies as well as by agricultural cooperatives and by food-processing companies valorizing their own by-products. Today a strong compound-feed industry is marketing compound feed as complete rations, large supplements and premixes all over Europe. It has contributed significantly to the technical revolution and economical improvement of European livestock production. Animal feed is the largest single item of expense in the production of milk, meat and eggs, often accounting for up to 70% of total cost. The high efficiency of present day animal production is achieved by the combined efforts of all concerned: (1) livestock farmers readily accept new techniques for improving the efficiency of their operations; (2) research has achieved valuable results in genetics, nutrition and management to produce quality products at the least possible cost; (3) governments foster the developments in research, advise livestock farmers and issue the necessary regulations. The feeding of compound feed, based on scientifically-calculated formulae, especially as complete rations (all-mash or pellets), to pigs and poultry can put the results of nutrition research and innovations to work in practice, very quickly and efficiently. Complete rations save labour on the farm, improve the efficiency of the feed and help to utilise new feed resources. The feed industry has a big impact, not only on the introduction of new feed resources into livestock production, but generally on the whole trade with feedstuffs. This became even more important with the application of least-cost formulation by linear programming on computers. The mixing of authorized feed additives into compound feeds to meet the requirement of the animal for specific minor nutrients, to improve performance and to prevent disease, became a wide-spread practice. Moreover, compound feed can be used by veterinarians as medicated feed to prevent or cure diseases in large herds of animals, where individual treatments are very time and labour consuming.

198

The cost of transportation, particularly of roughages, puts an economic limit on the use of complete rations on the farm. In many areas, livestock production depends essentially on home-grown feed, supplemented by feedstuffs not available on the farm. UTILIZATION OF COMPOUND FEED

General Compound feeds can be classified according to their quantitive importance in the ration of the various animals. They are fed: (1) as complete diets (allmash, pellets, crumbles ); (2) as basic diets to be supplemented by home-grown feed or by-products; (3) as quantitatively-important supplements to homegrown feed by-products; (4) as a vitamin/mineral pre-mix, representing quantitatively a minor component of the ration. The proportion of compound feed in the total ration, i.e. compound feed supplemented with a minor percentage of home-grown feed or, on the other extreme, home-grown feed with a minor part of supplements is highly variable. It depends on the feeding system for the particular livestock and on the resourses of feedstuffs available in the area under consideration. Therefore, we prefer to distinguish roughly between a complete diet and various types of supplements and pre-mixes.

Complete diet A complete diet is the usual method of feeding poultry in modern production systems. It contains all essential nutrients and micro-ingredients to meet the requirements of the animals. Usually it is offered either as mash, crumbles or pellets. Egg production is based primarily on feeding mash or crumbles. However, because of animal-welfare considerations a trend to supplement all-mash with whole grains, as was common in the past, may again become important. Broilers are mainly fed crumbles or small pellets, owing to the fact that intake and growth are enhanced compared with all-mash feeding. Complete-diet feeding also is very common in intensive pig production, especially in pig-fattening units. Pellets are often used, owing to their easy, dustless handling, reduced separation and because intake, and thus efficiency, is often considerably increased. For lactating sows, complete diets are prefered because of the high requirement for readily-available nutrients. However, for gestating sows complete diets may provoke problems of poor satiety, if offered according to requirement. Complete diets, in the shape of pellets or crumbles, are often used for fish farming. Extruded feeds to fit in with the feeding habits of certain fish are becoming popular.

199 There is a definite trend to use complete diets, manufactured by compounders, for non-ruminant herbivores, like rabbits and horses. Whilst fattening rabbits with complete pellets is quite common and practical, disturbance of the digestion can occur with does if there is a lack of coarse structure in the pelleted feed. With horses and game animals, pellets are fed as a supplement to roughage. Feeding cobs with a coarse structure is another possibility for meeting the requirements of horses. Complete-diet feeding to ruminants can increase nutrient intake which is important for high-producing cows and finishing beef cattle. However, a coarse structure is essential. As home-grown forage is the basal feedstuff for ruminants, preparation of complete diets is usually done on the farms and not by the compound industry. The compound-feed industry tries to comply with the widely varying demands of the user. Standardizing the animal-production systems, as has been achieved in several countries, by concentrating animals in large units, simplifies the task of the compound-feed industry. The limits of these simplifications are the need to meet the requirements of the individual animal.

Supplements As mentioned above, the exclusive feeding of compound feed as a complete diet may interfere with problems of physiology and satiety of the animals and may not be economically feasible. The energy value of industrially-manufactured compound feed is generally relatively high, owing to the fact that the manufacturing costs are judged by the market in relation to the cost of the energy or nutrient unit. Including high amounts of coarse-structured ingredients to overcome physiological problems, as, for example, roughage in compound feed, is in general too costly, and often not able to compete with roughage on the farm. Thus the compound-feed industry produces a wide variety of supplements and pre-mixes to be added to various feed stuffs, such as cereals, byproducts and forage: (1) for poultry, to be supplemented with whole cerealgrain; (2) for sows and pigs, to be fed with cereals, especially maize (kernels, cobs, whole plants, dry or silage) and/or with by-products of the dairy and meat industries (dried skim milk, dried whey and slaughter offal), sometimes also with roughage and kitchen waste; (3) for ruminants and other herbivores as supplement to forage (green or conserved as silage, hay etc.); (4) protein and mineral/vitamin pre-mixes often including the necessary additives to upgrade home-mixed and home-grown feed stuffs. The accuracy of proportioning between supplements and pre-mixes on the one hand and other feedstuffs on the other, on the farm itself may cause some problems. It requires knowledge of the value and the intake of the basal feed.

200 QUANTITATIVE IMPACT OF COMPOUND FEED

Raw materials In the world, ruminants for milk and meat production represent 80% of the total livestock. According to Wheeler et al. ( 1981 ) cattle, buffaloes, sheep and goats consume about 68 and 78% of concentrates (grains, oil meals) and forage, respectively, available for livestock (Table I). The percentage of concentrates and roughage in the years 1970-1983 used for livestock in the E.E.C. countries is shown in Table II. About 30% of the concentrates, calculated on an energy basis, were imported from outside the E.E.C. Calculated on a protein basis the percentage amounts TABLEI Partition of feed for livestock groupsa, Wheeler et al. (1981) Concentrates

Cattle b Sheep Pig Poultryc Other d Total

Forage

Cereals

Oil meal

Other

Total

35 2 32 27 4 100

21 3 28 45 3 100

37 7 39 13 4 100

56 12 10 7 15 100

63 15 2 1 19 100

aBased on metabolizable energy (1979/80 data). bFor meat and milk production only. CFor egg and meat production. °Mainly draught animals. TABLE II Mean percentage of forage and concentrates over a period of 13 years, estimated for E.E.C. countries

Forage • Permanent pasture Other grassland Maize silage Total Concentrates Cereals Other marketable feedstuffs Total

Energy basis (%)

Protein basis (%)

44.5 7.3 4.7 56.5

51.3 6.2 3.0 60.5

24.8 18.7 43.5

13.1 26.4 39.5

201

to 56%, showing that residues of oil/seed extraction and corn gluten especially are imported. During these years, a significant trend in the increased production of maize silage and home-produced cereals and of increased importation of other marketable feedstuffs appears. The upward trend of imports of protein-rich feedstuffs seems to have been broken in the last few years (1983-1985). This can, in part, be attributed to the price relationship between oilseeds and grains. On the other hand, pasture and grassland production decreased during the last 15 years, which is true for the imports of cereals because of large surpluses in the E.E.C.

Compound feed The proportion of compound feed in the total feed intake is less for cattle than for pigs and poultry. Table III shows that about 50 and 70% of the rations for pigs and poultry, respectively, consists of compound feed. In general, about 50% of the cereals produced in 10 E.E.C. countries are fed to animals. About one third of the production is used for human consumption and the rest is exported to countries outside the E.E.C. Table IV shows the estimation of the production and utilization of cereals in the year 1986/1987. About 42% of the cereals fed to animals are processed by the compound industry. The amount of cereals in compound feed is shown in Table V. From the data in Table V it can be concluded that a great part of compound feed consists of by-products from the food-processing industry (flour milling, oilseed extraction, meat- and fish-processing). The compound-feed industry helps, to a great extent, to recycle the offal of food processing into animal production, whilst meeting the best possible quality-price relation and maintaining at the same time the price level of the basic raw material. The use of compound feeds by various classes of animals is shown in Table VI. The allotment of the compound feed to the various livestock classes differs TABLE III Amount and proportion of compound feed in the total consumption, calculated on the basis of feed units (1 kg barley= 1 FU) in 8 E.E.C. countries Year

1973 1978 1983 1984 1985

Cattle

Pig

Poultry

Others

Total

Mt

(%)

Mt

(%)

Mt

(%)

Mt

(%)

Mt

(%)

16.9 24.6 29.2 29.5 29.0

9.8 14.3 17.1 17.4 17.2

21.4 25.0 26.8 26.7 26.5

50.4 53.9 53.5 51.0 50.9

18.3 19.1 21.9 21.1 21.0

67.5 68.0 70.0 70.4 68.2

2.0 3.0 3.5 3.7 3.6

9.5 11.8 13.8 14.0 13.3

58.6 71.7 81.4 81.1 80.1

22.2 26.4 29.3 29.1 28.1

202 TABLE IV Production and utilization of cereals in 10 E.E.C. countries in Mt

Production Utilization Consumption Human Animal Compounded Not compounded

1974/75

1977/78

1980/81

1983/84

1986/87"

111.0 117.8

105.6 114.9

124.8 117.7

123.3 116.4

134.8 114.1

45.3 72.5

45.2 69.7 28.7 41.0

46.9 70.8 30.2 40.6

46.2 70.2 29.8 40.4

44.8 69.3 29.0 40.3

b b

aEstimated. bNot stated. TABLE V Amount of cereals in compound feeds in 9 E.E.C. countries in Mt 1975/76

1977/78

1980/81

1983/84

1986/87"

Cereals Other components

27.0 34.7

29.2 49.3

29.4 50.1

29.0 53.3

28.2 52.3

Total Percent cereals

61.7 44

78.5 37

79.5 37

82.3 35

80.5 35

aEstimated. TABLE VI

--"

Compound-feed production in the year 1985 in various European countries (F.E.F.A.C., 1986) Cattle Mt F.R.G. France Italy The Netherlands Belgium U.K. Ireland Denmark Austria Switzerland Portugal Spain a Total Mean (x) SD (%) a1984.

7.1 3.5 3.9 5.7 1.4 4.5 1.2 1.7 0.1 0.2 0.6 2.5

Pig (%) 43 24 36 35 28 44 60 39 11 25 25 21

32.4

Mt 5.8 4.3 2.4 6.9 2.6 2.1 0.4 2.0 0.3 0.4 0.9 4.2

Poultry (%) 35 29 22 42 52 20 20 47 33 50 38 36

32.3 33 13

Mt 3.2 5.5 4.1 3.4 0.9 3.2 0.3 0.5 0.4 0.1 0.8 4.0

Other (%)

Mt

(%)

19 38 38 21 18 31 15 12 45 13 33 34

0.5 1.3 0.4 0.3 0.1 0.5 0.1 0.1 0.1 0.1 0.1 1.1

3 9 4 2 2 5 5 2 11 12 4 9

26.4 35 11

4.7 26 11

6 4

203 TABLE VII Compound-feed production in Europe compiled from various sourcesa Country

Year

Austria Belgium Bulgaria C.S.S.R. Cyprus G.D.R. Denmark Finland France F.R.G. Greece Hungary Ireland Iceland Italy Luxemburg The Netherlands Norway Poland Portugal Rumania Spain Sweden Switzerland Turkey U.K. U.S.S.R. Yugoslavia

1981 1985 1980 1980 1979 1980 1982 1981 1983 1983 1983 1983 1982 1982 1983 1985 1986 1976 1980 1980 1975 1985 1985 1986 1983 1982 1985 1981

Total

Mt year- 1 1.1 5.4 4.4 5.0 0.4 4.5 4.6 1.5 15.4 17.8 2.4 4.0 1.8 1.9 11.2 0.1 16.5 1.3 4.2 3.5 4.0 11.8 2.2 1.3 2.3 11.8 70.0 3.4 214.0

~Personally communicated by F.E.F.A.C.; Buhler; Boucqu$; V.S.F. (1987).

considerably between the countries. This could be taken as reference to the different production specialization and feeding systems in the respective countries. As a mean about one third of compound feed is processed for cattle and pig feeding, respectively, one quarter for poultry and the rest for various animal species. A complementary estimation of total compound-feed production is shown in Table VII.

204

FEED ADDITIVES

General The inclusion of minor quantities of specific components of natural or synthetic origin into compound feed is a common practice in industrial nations. To prevent possible adverse effects to the animal, to human beings and to the environment, the feed additives have to be approved by the various state-registration authorities. The requirements for clearance of a specific additive are based on the various national laws as well as on European and international conventions. The strictness of the requirements depends, in the main, on the type of the substance and the potential risk of adverse effects for man, animals and the environment. This policy is nowadays widely, but not always unanimously accepted. In general the following information on the additive concerned is required for clearance: (1) identification based on good laboratory practice; (2) chemical, physico-chemical and technological properties; (3) assignment of application concerning animal species as well as time and quantity of application; (4) methods of qualitative and quantitative analysis in the feed as well as of residues in the animal product, including metabolites of the substances; (5) metabolism, pharmacological and biological effects or side effects and possible toxicological effects, including mutagenicity, teratogenicity and carcinogenicity; (6) possible hazard of build-up populations of pathogenic microorganisms which are resistant or cross-resistant to antimicrobial agents, indispensable for medical use; (7) efficiency in respect to the desired effect on the animal. The strict and very extensive requirements for the clearance of a substance as a feed additive can be met only with laborious screening of new substances by technical specialists of all kinds. Thus the development of a new additive can take between 8 and 10 years, at great expense.

Types of additives General Substances which are allowed to be added to compound feed in small quantities can be classified in two principal categories: (1) Additives, which are essential for the maintenance of the biological functions of the animals. Vitamins and trace elements are typical examples of this category. The requirements for approval of these additives are in general less severe. However, they have to be more severe if adverse effects are expected from feeding in excessive quantities or if there are traces of undesirable substances in the additives which appear subsequently in meat, milk or eggs. (2) Additives, which are not essential for the biological function of the animal, but which have a specific, positive effect on the clinical healthy organism.

205 Growth promoters are the most typical example of this kind of additive. Substances which directly modify the hormonal or nervous regulation of metabolism are another example of non-essential additives. Both categories of additives have no nutritive value per se but they improve the nutritive value of the feed and thus the performance of the animal and the efficiency of feed conversion. The inessential feed additives of the second category can be grouped as follows: technological additives; absorption enhancers; antimicrobial agents; other growth promotors; metabolic modifiers; probiotics; prophylactics. We use this pragmatic classification, bearing in mind, that several additives could be classed with more than one group. Besides, feed additives, having a prophylactic effect, are on the borderline between nutritional and medicinal use. The feed industry and animal nutritionists also make use of a third category of feed products, which are added in small quantities to compound feed. This group includes individual amino acids and other organic acids, propyleneglycol, urea and others. The addition of such components may be looked on as being essential for a specific production system but not for the maintenance of the biological function. Apart from propyleneglycol, which is used for feed processing reasons, they have a specific nutritive value and may enhance animal performance.

Technological additives Preservatives. Based mostly on organic acids (e.g. propionic acid, fumaric acid) these components can reduce or prevent the development of bacterial or mycological spoilage of feed. However, they may conceal the presence of spores and thus the possible former growth of microorganisms, which may have produced toxins.

Antioxidants. Antioxidants are frequently added to protect components of the feed, which are sensitive to oxidation. They include natural or synthetic tocopherols and lecithin as well as various synthetic products. Antioxidants are used especially to protect unsaturated fatty acids in fats and oils, Vitamin A, carotene and carotinoids.

Pelleting, free-flowing agents and dust preventives. To improve the pelleting of feeds, various agents, mostly of negligible or very low nutritive value, are added to compound feed. They include argillaceous earths as for example montmorillonite or various derivatives of lignosulfate and cellulose. To improve the flow characteristics of compound feeds, flowing agents (various silicates) are added.

206

Flavours. Flavours are single spices or mixtures of spices, as well as synthetic aromatic compounds. They are sometimes used to conceal unattractive natural smells, tastes or structures of feed, to enhance feed intake. Opinions on the advantage of using flavours in animal production are still controversial.

Colours. For poultry and fish production, colouring agents, mostly carotinoids of natural or synthetic origin, are often added to the feed for a distinct colouring of the animal product, to make it more attractive to the consumer. This affects the colouring of the egg yolk, skin of broilers or meat of fish. To distinguish clearly medicated feed from other feed colouring agents are sometimes added.

Absorption enhancers Enzymes. The addition of proteolytic and amylolytic enzymes to the feed is sometimes done, to increase the digestion and absorption of less digestible feedstuffs. Until now, tests with various enzymes, produced by extraction from organs of animals (rennin, pancreatic juice) or from microorganisms did not prove consistent efficacy.

Emulsifiers. To reduce the particle size of fats for better digestion and absorption, emulsifiers are incorporated into milk replacers. Emulsifiers are also used to administer fat-soluble vitamins to animals in aqueous solution. Natural emulsifiers such as lecithin and saponin as well as synthetic emulsifiers are customary.

Antimicrobial agents (growth promotors) Antimicrobial agents are added in comparatively small amounts to improve daily weight gain and feed-conversion ratio of fattening animals. Two classes of antimicrobial agents may be distinguished: (1) antibiotics, which are metabolites of living cells ( fungi, bacteria); (2) chemotherapeutics, which are chemically synthesized. This distinction is widely accepted, although antibiotics produced by bacteria are sometimes modified by stepwise chemical transformation. Thus several products could be allocated to either class. Since about 1970, most authorities have striven for a clear distinction between antimicrobial agents used for growth promotion and others for therapeutic use, either for human or animal therapy. But this distinction is not strictly maintained. The antimicrobial agents used for growth promotion are nowadays not significantly absorbed in the intestine. They are qualitatively and quantitatively effective on the microbial population of the intestine, including the rumen. This entails in principle an increased efficiency of utilisation of nutrients, al-

207

though variable for various animal species and age classes. The greatest effect is observed with young animals. The following mean improvement of the daily weight gain at a given feeding level has been estimated: (1) poultry, broiler 2-5%; (2) pigs, piglet 10-20%, weaner 5-10%, finishing 2-5%; (3) cattle, suckler calf 10-15%, bull 2-10%. Simultaneous improvement of the feed-conversion ratio occurs. The degree of this improvement depends on the feeding level (restricted or ad libitum feeding) and the response of the animal in respect of the composition of the product (liveweight gain, milk). A wealth of literature exists on this subject. The use of antimicrobial agents for growth promotion, with or without veterinarian prescription, is subject to strict regulations in all European countries. As these regulations differ between countries and may be altered at short notice, the reader is referred to national authorities for precise information.

Other growth promotors Copper. The addition of copper to pig feed in higher amounts than are necessary to cover its requirement as a trace element has a growth-promoting effect. Especially in feeds for young growing pigs 75-175 mg k g - 1 feed may be added. Higher amounts may be harmful to the function of the liver of the pig. Using such high amounts of copper increases the danger of pollution of the environment through the manure of the pigs. Therefore a maximum level of 35 mg k g - 1 feed is applied now for growing pigs in some countries.

Metabolic modifiers Metabolic modifiers consist of substances which directly influence the cellular metabolism of the animal, rather than the activity of the digestive tract, or the microbial population therein. The present generation of metabolic modifiers includes hormones and hormone-like substances, as well as synthetic compounds which have a direct effect on the nervous regulation of metabolism. Steroidal hormones, of either natural (testosterone, oestradiol and progesterone), or synthetic origin (trenbolone and zeronal), have been widely used. The stilbene compounds, diethylstilboestrol, hexoestrol and dienostrol were also used at one time, but since 1981 their use has been widely prohibited. All these compounds positively affect the metabolism of growing and fattening animals, especially cattle, reducing the deposition of fat and increasing the proportion of protein in the liveweight gain. Such an effect is regarded as desirable from the human dietary viewpoint. Because steroidal hormones are also active by mouth in humans, their use was restricted to slow-release implants of materials with lower levels of oral activity, and withdrawal periods were instigated, as well as the discarding of the site of the implant. If the recommended procedures were followed, the level of steroidal hormones detected in meat from treated animals presented no haz-

208

ard to the health of the consumer (E.E.C. 1982). Nevertheless, the E.E.C. introduced a complete ban on the use of steroidal sex hormones in animal production in December 1985. The trigger for this decision was probably the evidence that withdrawal periods and procedures for the discarding of tissues in the area of the implant were not always being followed. Research is currently in progress on growth hormone, or bovine somatotropin, BST, a protein hormone which is species specific and not effective by mouth, since the protein molecule is digested by the enzyme systems of the animal. BST is secreted by the pituitary gland, and has a profound influence on many bodily functions, particularly lactation, as well as growth. Milk yield increases of 2-4 kg day- 1 have been recorded, accompanied, after some delay, by an increase in feed intake to maintain energy balance. The manufacture of BST on a commercial scale is now possible, using recombinant-DNA techniques. The levels of the hormone in the meat and milk of treated animals are of the same order as in untreated animals, since all animals secrete the hormone themselves. Bovine, ovine or porcine BST are not effective for humans, whatever the route of administration. The search for other metabolic modifiers for more profitable animal production continues, with the aim of replacing not only the steroid hormones and other directly-acting hormones, but also the antimicrobial growth promoters. Research is being directed to hormone-releasing factors and substances, which would alter the level of secretion of the hormones of the animal, or alter or depress nervous signals. As an example, the beta-agonists, Clenbuterol and Cimaterol can have such effects, but some are known to influence the cardiovascular system or the motility of the digestive tract. Since such compounds are also active in the human, residues in meat may be a problem. It is evident that the authorities should approve such substances only after very careful and conscientious verification of all possible harmful effects on animals, man and the environment. For the time being, it would be premature to promote the general use of substances which have a direct effect on the physiology of the animal at the cellular level, although some promising research results are available.

Probiotics The term 'probiotics' is used for deep-frozen bacteria which are revived if fed to the animal. They are claimed to have a regulatory effect on the microbial micro flora. Their effect on growth promotion is until now not clearly proven. They may have a certain impact on the reconstitution of the intestinal microflora after antibiotic treatment.

Prophylactics According to official regulations, only agents to prevent coccodiosis in poultry and rabbits may be used as prophylactic feed additives. However, the use

209 of antimicrobial agents in slightly higher dosages than those effective for growth promotion is often claimed to have a disease-preventing effect. This is often debated between veterinarians and nutritionists, bearing in mind t h a t some antimicrobial agents are also effective against protozoa.

REFERENCES E.E.C., 1982. Interim Report of the Scientific Working Group on Anabolic Agents in Animal Production, No. 2924/IV/82. F.E.F.A.C., 1986. Statistical Yearbook, European Federation of CompoundAnimalFeedingstuffs Manufacturers, Brussels. Wheeler, R.O. et al., 1981. The WorldLivestockProduct, Feedstuffand Food Grain System.Winrock International, Morrilton, AR, U.S.A.

Livestock Production Science, 19 (1988)211-216 ElsevierSciencePublishersB.V., Amsterdam-- Printed in The Netherlands

211

III. F E E D E V A L U A T I O N A N D N U T R I T I O N A L REQUIREMENTS III. 1. I n t r o d u c t i o n H. BICKEL GENERAL The production potential of feedstuffs has to be expressed above all by the energy content of the feed, representing the whole of the organic matter. It is well known that, besides this, potential has to be defined simultaneously by the protein content as a specific component of the organic matter, and more precisely by the contents of the essential amino acids, especially in feedstuffs for non-ruminants. Thus feed evaluation was, and is, always orientated on the energy value and the protein value of the feed, although other components are to be considered for their specific effects in nutrition, e.g. lipids, dietary fibre, vitamins, minerals, trace elements etc. NUTRITIVE VALUE All modern feed-evaluation systems approach the production potential in a similar way. They are all based on two common principles: (1) definition of the digestibility of both the energy and the nutrients; (2) distinction between animal species and between type of production. Calorimetric measurements and/or proximate chemical analysis of feed and faeces are necessary to determine digestibility. The use of standard caloric values of the individual nutrients may replace calorimetry. Taking additionally into account the energy loss as urine (and methane) a more precise base is attained. Moreover, several systems make allowance for dietary-induced heat production. Energy

The amount of energy available for the animal is thus estimated conventionally according to the following models: (1) digestible energy (DE) = gross energy (GE) of f e e d - GE of faeces; (2) metabolizable energy (ME) = DE - ( GE of urine and methane); (3) net energy (NE) = ME - dietary-induced thermogenesis (heat increment). 0301-6226/88/$03.50

© 1988ElsevierSciencePublishers B.V.

212

A comprehensive model, examining the true biological partition of GE was proposed by Harris (1963) and further developed by the CAN subcommittee on biological energy (N.A.S., 1981). DE and ME are relatively easy to measure, especially if the measurement of methane is omitted. Both energy terms are in use for ruminants and pigs. Poultry feed is generally evaluated as ME, because birds excrete faeces and urine together through the cloaca. Thus quantitative distinction is complicated. The measurement of the dietary induced thermogenesis cannot be done independently of the basal-heat production. Thus, it has to be estimated as heat increment (HI), attributable to a definite increment of feed intake. Conventionally, this heat increment is indirectly expressed by the partial efficiency of utilization of ME, assigned by the symbol k. HI=ME-NE k = NE/ME

Usually linearity of k over the possible range of production is assumed: NE=MExk

Heat increment and thus the value of k are dependent on the type of production involved. Thus, for the estimation of the energy value of feedstuffs and for the estimation of energy requirement, the various types of production to consider are, e.g. km for maintenance, k~ for lactation, ko for egg production, kr for reproduction tissue, kg for gain (generalized), kf for fat deposition, kp for protein deposition. In summing up, metabolizable energy seems to be the most universal term to define the overall production potential of the feedstuff for the various animal species and the various production systems. Protein

As far as protein evaluation is concerned, apparent digestible crude protein (DXP) is conventionally thought to be the most simple way to express the production potential of protein. DXP is defined correspondingly to digestible energy D X P = c r u d e protein of feed ( X P ) - X P of faeces

where XP stands for total nitrogen, multiplied by 6.25, the average ratio of protein to nitrogen. Looking at the anatomy and the physiology of the various animal species, e.g. ruminants, pigs and poultry, the limits of this evaluation system can be recognized. Modern concepts to express the potential of the feed to cover the protein requirement of ruminants consider the quantity of amino acids absorbable in the small intestine and the pattern of these amino acids. Allowance

213 for microbial metabolism in the rumen is thereby made. For pigs, digestible protein, defined more precisely as apparent digestible protein, is still a fair approach to protein evaluation. However progress is focused to consider absorbability of amino acids in the small intestine, as well as the amino-acid pattern of the digested feed. For poultry, the evaluation of protein on the basis of digestible protein is not very practicable, owing to the combined excretion of faeces and urine. Therefore evaluation systems tend to consider crude protein and in addition amino-acid availability when defining the protein potential of the feedstuffs. In summary, protein-evaluation systems of feedstuffs for the various animals tend to consider as precisely as possible the amino acids absorbable in the intestine, in replacement or in addition to crude or digestible protein.

Standardization in feed evaluation It is generally recognized that substantial progress in the knowledge of feed utilization came about during the last decades, and valuable evaluation systems are offered by scientists. However, it is unavoidable that standardization and even some simplifications have to be accepted. As an example, additivity of the values of the individual feedstuffs in the ration is assumed as a rule, which seems to be true in most cases, although some exceptions cannot be excluded. How far this standardization can or should go depends on judging the applicability of the evaluation system for practical ration formulation. One main difference between the feed-evaluation systems, proposed and applied in various countries both for energy and protein evaluation as well as for the various types of animals and productions, is thus based on this judgement. One of the goals of the following chapters is to identify the common basis and the main differences between the feed-evaluation systems in use in Europe. NUTRIENT REQUIREMENTS

Factorial approach Feed evaluation is always aimed at meeting the requirements of the animal. Animal nutritionists approach the estimation of the requirement by splitting the total requirement into various components, e.g. requirement for maintenance and activity, for milk production, for body gain, for egg production, etc. This is the factorial approach. Total requirement is obtained by summing up the partial requirements.

214

Standardization in nutrient requirements As with the procedure for feed evaluation some standardization and simplification may be judged to be necessary for practical application. Besides, real differences in the requirements and gaps in knowledge, sometimes masked by so-called safety margins, exist for different production systems. Thus, feeding standards are often based on feeding trials rather than on the factorial approach, especially for pigs and poultry. The variabilities of nutrient utilization and of animal requirements, including interactions of nutrients and protein to energy relationship, are sometimes understood and allowed for by results from carefully-planned feeding experiments as accurately as by the factorial approach. Therefore, it is obvious that recommended allowances and feeding standards in the various countries are often difficult to compare in a simple way. FEED INTAKE

To set up rations and feeding rules for a desirable level of animal performance, which corresponds to the genetic potential, requires knowledge of the intake of the animal. Whilst in some production systems the intake is accurately known by restricting the daily amount of feed, other systems are based on ad libitum feeding where intake can be estimated but not measured. Besides, in many systems, group feeding dominates over individual feeding and determination of the requirements of groups only, and not of individuals, is possible. Thus recommended allowances are often expressed not at a per diem rate but as the recommended content of the ration, e.g. of the feed mixture. This is especially the case in poultry feeding, but also applies in some systems of ruminant and pig feeding. Thus the practical application of the science of animal nutrition deals with the formulation of diets from a selection of feeds which, when given to the group of animals under consideration, will result in achievement of the desired level of animal performance at an economic level of cost in relation to the expected returns. As has been stated above, two quite separate sets of information are needed, expressed in a common set of units. The first relates to the nutritive value of feeds as measured by their voluntary intake, digestibility, chemical composition, content of anti-nutritional factors etc. The scientific units used vary between countries, although many are derived from common scientific measurements or principles. Data are then assembled into tables of feed composition and nutritive value, expressed per kilo of feed, either as fed to the animal, or on a dry matter basis, since water, although essential, has no nutritive value. The second set of data relates to the requirement for nutrients of many types, by the various classes of ruminant livestock, for various levels of animal pro-

215 duction, for the production of meat, milk or reproduction. This must include data about the amounts of feed that animals can consume, and their reaction to short- or long-term deficits or surpluses of nutrients. RATION FORMULATION Ration formulation consists of assembling feeds in such amounts that the sum of the particular nutrients supplied by the individual feeds is equal to the animal's requirement for that nutrient. Mathematically, each nutrient is handled in a linear equation of the form: aX1 + bX2 + cX3 + d X 4 = R ( X )

where a,b,c, and d are the amounts of each feed in the diet; X1,X2,X3 and X4 are the content of Nutrient X in feeds A,B,C and D and R (X) is the animal's requirement for Nutrient X. A large number of nutrients have to be considered, especially when trace elements and vitamins are included and a matrix of linear equations has to be solved. Whilst simple rations can be formulated by hand or with simple calculators, the use of the computer is common, using the technique of linear programming to devise diets which are of least cost for the feed prices extant at the time. Within this matrix, certain nutrients such as protein and energy tend to dominate costs, whilst trace elements are usually a minor cost. For nutrients such as the major minerals and trace elements, there is almost world-wide agreement on the units to be used, usually either g kg -1 or mg kg -1, although the use of percentages (%) and parts per million (ppm) still continues. Requirements for these minor nutrients are also much more generally agreed, with exceptions such as phosphorus. SYSTEMS In the following chapters the main lines of the various systems of feed evaluation and nutritional requirements, including recommended allowances, proposed and used in the various countries are explained. Similarities and differences between the systems for the various types of animals and productions are identified, as far as information from the various countries is available. A glossary of terms and the relevant symbols are given by van der Honing and Alderman in the following chapter (III.2) on Page 225 (Table III). Space does not permit the explanation of the full background of all feed-evaluation and nutrient-requirement systems. Therefore readers are referred to standard texts on animal nutrition for a detailed explanation.

216 REFERENCES Harris, L.E., 1963. Symposium in feeds and meats terminology. III. A system for naming and describing feeds, energy terminology and the use of such information in calculating diets. J. Anim. Sci., 23: 535-547. N.A.S., 1981. Nutritional Energetics of Domestic Animals and a Glossary of Energy Terms. National Academy of Science, Washington, DC. Van der Honing, Y. and Alderman, G., 1988. Feed evaluation and nutritional requirements. 2. Ruminants. Livest. Prod. Sci., 19: 217-278.

Livestock Production Science, 19 (1988) 217-278

217

Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

III. 2. R u m i n a n t s Y. VAN DER HONING and G. ALDERMAN

GENERAL

There are many different systems for the measurement of the energy and protein contributed by feeds, and the ruminant animals' need for these major nutrients, in use in Europe. The intention of this chapter is to outline briefly the many European systems for estimating the energy and protein requirements of ruminants, to indicate the common basis of the recently-introduced systems, and to discuss methods of conversion of one unit to another. The terminology and symbols used are detailed in Table I. SYSTEMS FOR ENERGY EVALUATION OF FEEDS AND ENERGY REQUIREMENTS FOR RUMINANTS

Introduction Two decades of calorimetric measurements of the energy requirements of dairy and beef cattle and of sheep, at several centres of excellence, resulted in the publication of a number of new systems for calculating energy requirements of farm livestock. In the decade 1970-1980, the majority of European countries replaced their existing energy systems. The latter were based on the Kellner starch-equivalent system (Kellner, 1905) or on fodder units calculated from it. The newer systems use a common concept, based on the proposition of Blaxter, that metabolizable energy (ME), i.e. gross energy minus energy in faeces, urine and methane, is the basis for energy evaluation. Net energy (NE) systems are derived from metabolizable energy, involving the partial efficiency of utilization (k) of ME. Net energy of feeds for maintenance, lactation and gain are calculated using coefficients k ~ k~ and ks, respectively. The magnitude of these coefficients depends on the metabolizability (q) of the gross energy. Because of the variation of k for various production forms, some simplifications are necessary to define energy values, which can be used for maintenance and lactation or maintenance and gain together. Systems for dairy cows were rather easy to simplify because of similar slopes for the equations for k~ and kl. Van Es (1975) used 1.2 for the proportion between km and kl. McHardy (1966) proposed the use of a common king for 0301-6226/88/$03.50

© 1988 Elsevier Science Publishers B.V.

218 TABLEI Terminology and symbols used Chemical analyses of animal feed ADF ADL DCHO DM DMF DMI DMTP DOM DOMD DTP ds DUDP DXF DXL DXP DXX GE IDOM MXP MTP NDF NPN OM RDP TDN TP UDP XF XL XP XX

Acid detergent fibre (van Soest) Acid detergent lignin (van Soest) Digestible carbohydrates Dry matter Faecal dry matter output (g or kg day -1) Dry matter intake (g or kg day -~ ) Digestible microbial true protein Digestible organic matter Digestible organic matter in dry matter Digestible true protein Digestibility coefficient of nutrient indicated by subscript Digestible undegraded protein Digestible crude fibre Digestible crude fat Digestible crude protein Digestible nitrogen-free extract Gross energy Indigestible organic matter Microbial crude protein Microbial true protein Neutral detergent fibre (van Soest) Non-protein nitrogen Organic matter Degraded dietary crude protein Total digestible nutrients True protein Undegraded protein Crude fibre Crude fat Crude protein Nitrogen-free extract

Energy units and coefficients used to describe systems APL DE dE

Eg Em Ep SVg FL FM FU

Animal production level,usually expressed as a multiple of maintenance requirement Digestible energy Digestibilityof energy = D E / G E Net energy required for body gain (MJ day -I ) Net energy required for maintenance (MJ day-i) Net energy required for production (MJ day -I) Energy value of gain (MJ kg- i) Level of feeding, relativeto maintenance Fasting metabolism (MJ day- I) Fodder unit, i.e.the starch equivalent of i kg barley as fed

219 TABLE I (continued)

kf kg kl k~

krag k~ kp LWG Mcal ME ME/DM MEm MJ NE NEg NE~ NEm

NEmg q SE W

Efficiency of utilization of ME for fattening Efficiency of utilization of ME for body gain Efficiency of utilization of ME for lactation Efficiency of utilization of ME for maintenance Efficiency of utilization of ME for maintenance and gain Efficiency of utilization of absorbed amino acids Efficiency of utilization of ME for protein deposition Liveweight gain ( kg d a y - 1 ) Megacalorie -- 1000 kcal -- 418.4 kJ Metabolizable energy ME concentration of dry matter (MJ kg- 1) ME required for maintenance (MJ d a y - 1) MegaJoule = 1000 kJoule Net energy of a feed or ration Net energy value of a feed or ration for body gain (MJ kg- 1) Net energy value of a feed or ration for lactation (MJ kg- 1) Net energy value of a feed or ration for maintenance ( MJ kg- 1) Net energy value of a feed or ration for maintenance and gain ( MJ kg- 1) Ratio of ME to gross energy, metabolizability of gross energy ( % ) Starch equivalent, defined as the fattening potential of 1 g digestible starch, which is equal to 2.36 kcal or 9.88 kJ Liveweight in kg

Energy system code letters EFr FFU ME(GB) ME(IRL) ME(S) ME(SU) MSV NEL(CH) NEL(D) NEL(GR) NEL(H) NEL(US) NEL(YU) NEM(YU) NEV(CH) OFU SFU(DK) SE(NL) SEK TDN UF UFL UFV UN(RO) VEM VEVI

Energy for fatteningof ruminants from German Democratic Republic Scandinavian fatteningfeed unit,used in Norway and Finland Metabolizable energy from M.A.F.F. Bulletin 33 Metabolizable energy (Ireland) Metabolizable energy (Sweden) Metabolizable energy (U.S.S.R.) Net energy fat,modified starch unit (EFt) in Greece Net energy lactationin Switzerland Net energy lactation1982 in the Federal Republic of Germany Net energy lactationin Greece Net energy lactation1986 in Hungary Net energy lactatingcows N.R.C. 1978 (used in Israel) Net energy lactation1984 in Yugoslavia Net energy for growth and fattening 1984 in Yugoslavia Net energy growth and fatteningin Switzerland Oat feed unit in the Union of Soviet SocialistRepublics (U.S.S.R.) Scandinavian feed unit system according to the Danish procedure Starch equivalent system (Dutch modification) Starch equivalent system according to Kellner Total digestiblenutrients Unith foraggere in use in Italy French net energy unit for dairy cows French net energy unit for beef cattle Net energy lactation1984 in Rumania Dutch net energy unit for dairy cows Dutch net energy unit for beef cattle

220 growing cattle by introducing the concept of Animal Production Level (APL) which calculated a variable NEmg depending on level of production, first adopted by the U.K. This concept was also used in the internal arithmetic of the Belgian, French, Dutch and Swiss systems, but using a fixed level of APL, 1.5. The majority of countries tested their new energy systems on feeding trials with breeds of livestock and feeds native to their countries and farming systems. In a number of cases, strict adherence to a factorial model has not been possible, particularly for growing and fattening cattle. The common ground for all new European systems is the measurement of the ME of feeds, from which the specific country energy units are calculated. Thus a set of ME values of feeds is basic to all systems. Brief details of the units introduced and the relevant mathematical functions will be given for Belgium, Denmark, Ireland, Finland, France, Israel, Italy, Germany: the Federal Republic of Germany (F.R.G.) and German Democratic Republic ( G.D.R. ), Greece, The Netherlands, Norway, Rumania, Sweden, Switzerland, the U.K. and Yugoslavia (see Appendix for details). Development of new energy systems, 1969-1980 Until the 1960s most European countries were using energy systems for ruminants essentially based on the work of Kellner (Kellner, 1905). The starch equivalent was defined by Kellner as the production potential of 1 kg digestible starch to form fat in adult male castrated steers. Thus the feed was evaluated as net energy fattening (NEf). Basically, this concept is still used by the energy system of ruminants (EFr) in the G.D.R., claiming that kg and km or kl are quite proportional together. The starch equivalent (SE) (either in kg or lb) was used, but the commonest unit was the fodder unit (FU), based on the SE of 1 kg of barley as fed, all other feeds being expressed as a proportion of the SE of barley. The unit was introduced as one that farmers could comprehend and is now firmly entrenched in many countries, although the methods of its calculation have been totally revised. A major variation, the Scandinavian feed unit (SFU) remains in use today in Denmark and Norway. A variation is the oat unit based on I kg of oats, since barley was not a familiar grain for farmers in Eastern Europe. The weight of evidence accumulating, and discussed in depth at the E.A.A.P. Energy Metabolism Symposia held every three years from 1958 onwards, weakened support for the existing SE and FU systems, because it was shown that no proportionality of kg and km occurs. It was quite clear that the use of NEf or SE values for meeting maintenance and lactation needs resulted in the under-evaluation of forages which Forbes and Wood had noted some 30 years before. An E.A.A.P. Feed Evaluation Working Group was formed under the leadership of A.J.H. van Es, with the objectives of seeking to formulate a new European standard system for the energy requirements of ruminants.

221

Events had already moved too far however, but van Es was able to secure a good deal of agreement on the central relationships now in use in The Netherlands, Belgium, France, Germany (F.R.G.), Switzerland, the U.K. and Yugoslavia, as can be seen in the Appendix to this paper. Van Es' net energy lactation system was published in 1975 (van Es, 1975 ), but the system adopted in The Netherlands appeared later (van Es, 1978). Details for France and Switzerland were published at the same time (Vermorel, 1978; Bickel and Landis, 1978). The Netherlands, Belgium and France all changed to a feed unit system based on 1 kg of barley, but with separate units for milk production and beef cattle. This eased the problems of change at the farm and advisory level, since most of the changes in calculation were hidden from view. Details of the following feed evaluation systems will be given in the Appendix on energy systems for ruminants: (1) starch equivalent according to the Kellner procedure (SEK), at this time still in use for beef cattle in the F.R.G. (D) and in several other countries; (2) the Dutch modification of starch equivalent ( SE (NL), until 1977 in use in the Netherlands (NL) and Belgium (B), and still used in Belgium for beef production; (3) Scandinavian feed unit according to the Danish procedure; SFU (DK) ; (4) fattening feed unit, used in Norway (N) and Finland ( SF ) : FFU; (5) energy system for fattening of ruminants (EFr), adopted in the German Democratic Republic (GDR); (6) metabolizable energy according to the Swedish procedure: M E ( S ) ; (7) metabolizable energy according to M.A.F.F. Bulletin: 33 ME ( GB ), used in the United Kingdom (GB). This system is also compared with the requirements described by the A.R.C., 1980; (8) net energy lactating cows, used in Israel (IL), described by the N.R.C., 1978: NEL ( US ); (9) metabolizable energy, ME (IRL), used in Ireland; (10) Dutch feed unit for milk production (VEM), and for body gain (VEVI), adopted in 1977 in The Netherlands and in 1978 VEM (only) adopted in Belgium; (11) French feed unit for milk production (UFL), and for body gain (UFV), adopted in 1978 in France (F) and revised i 1987 (see Addendum); (12) net energy for lactation, NEL (D), as adopted in the F.R.G. in 1982; (13) net energy lactation, NEL (GR), and modified starch unit, MSV, used in Greece; (14) Netto Energie Milch, NEL (CH), and Netto Energie Mast, N E V ( C H ) , used in Switzerland since 1979; (15) net energy lactation, N E L ( Y U ) , and net energy for growth and fattening, N E M ( Y U ) , used in Yugoslavia since 1984; (16) Unith foraggere, UF, in use in Italy; (17) net energy lactation, N E L ( H ) , and net energy beef (NEro and NE~), used in Hungary since January, 1986; (18) net energy for ruminants expressed as a new feed unit, U N ( R O ) used in Rumania since 1983; (19) (a) Oat feed unit (OFU) and (b) metabolizable energy, M E ( S U ) , used in the U.S.S.R.

The efficiency of utilization of metabolizable energy The concept of calculating net energies for growth, pregnancy and lactation from the measured ME available above maintenance requirements was put

222

forward by Blaxter (Blaxter, 1962). This was formalised in an A.R.C. Technical Review (A.R.C., 1965), where the following equations were published: Efficiency for maintenance (%), km = 1.6 ME/DM+ 54.6

(1)

Efficiency for fattening (%), kg = 4.4 ME/DM+ 3.0

(2)

Efficiency for lactation, k~, varied from 62 to 70% as a curvilinear function of ME/DM. Table values only were given. In 1972, Moe et al. (1972) published an NEI system based on a large data base of dairy cow energy balance trials. In this system, ME values are measured at the production level and converted to NE~ by the function: NE~(MJ kg -1 DM) =0.703 M E - 0 . 7 9 5

(3)

This implies an efficiency for lactation, kl, of 0.59-0.64. Another version of the NE1 system was proposed by van Es (1975), who preferred to use efficiencies for maintenance, growth and lactation to calculate relevant NE values. His equations are shown graphically in Fig. 1. The similarity of slope between km and k~ is quite obvious. Van Es therefore also proposed that variations in maintenance net energy due to variations in q 0.8-

km

0.7/

,," f

I

" kl

0.6-

Efficiency of utillisation of ME, k 0.5-

s /

/

/

0.4-

/ /

0.3-

/

0.2'

0.1 q

0 0

ME/DM

0.2 I

0.3 I g

0.4 I

0,5 I

0.6 I l~D

0.7 I

0.8 I 1'5

Fig. 1. Utilization of metabolizable energy for maintenance (kin), lactation (k~), fattening (kf) and maintenance+fattening (kmf) as a function of ME concentration in DM (ME/DM) and gross energy (q), ME/GE.

223 could be accommodated by calculating in terms of NEI and adjusting for the difference in intercept. To estimate q, the ratio between ME and gross energy {GE), in several countries the following equation from the work of Schiemann et al. (1971) is generally used:

GE=5.77 XP+8.74 XL+5.0 X F + 4.06 X X - 0.15 sugars

(4)

where GE is in kcal kg-1 and XP,XL, etc. are in g kg-1 and XP, XL, XF and XX are crude protein, crude fat, crude fibre and nitrogen-free extract, respectively. As a result of an E.A.A.P. Working Group led by van Es during the early 1970s, these equations formed the basis of new energy-evaluation systems introduced by The Netherlands, France, Belgium and Switzerland in 1977. They were later followed by Germany in 1981, Yugoslavia in 1984, and by Greece. The U.K. adopted a simplified version of the A.R.C. (1965) system in 1976 (M.A.F.F., 1975). Constant values were taken for km of 0.72 and k~ of 0.62, since the small variation due to M E / D M was not thought worth taking into account for the majority of mixed diets. Whilst the formulation of an NE~ system was fairly straightforward, because of the similar rates of change with q of both kr. and k~, the problem of growth and fattening net energies was much more complex. The coefficient for q in the kf equation was 2-3 times that for k~,, and therefore the calculation of a joint efficiency king was necessary. Obviously, the relative proportions of ME being utilized for each function would affect the calculated net energies. The problem was solved by McHardy ( 1966 ) but further developed and published by Harkins et al. (1974). McHardy introduced the concept of Animal Production Level (APL) which was the ratio of the total net energy to the net energy for maintenance

APL= (NEro + NEg) ~NEro

(5)

Net energy requirements of animals are independent ofq or ME/DM, whereas ME requirements depend upon q or ME/DM, making ration formulation rather complex and time consuming. Using this concept of APL, a function can be derived to calculate the joint efficiency of ME utilization for maintenance and growth/fattening as follows:

km X kg X APL k~g-kg+k~ (APL-1)

(6)

The results using the van Es equations for km and k~ over the range APL 1-2 ( maintenance to a liveweight gain of over I kg day- 1) and for M E / D M values ranging from 6 to 14 are shown in Table II. Whilst the general theory was concerned with rations, McHardy suggested that individual feed ME values could be transformed to feed NE~g values and

224 TABLE II Joint efficiency of ME used for maintenance and growth, king Animal production level (APL) 1.0 1.2 1.4 1.6 1.8 2.0

Ration energy concentration ME/DM, (MJ kg -1 DM) 6

8

10

12

14

0.65 0,52 0.45 0.41 0,39 0.37

0.68 0.59 0.53 0.50 0.47 0.46

0.71 0.64 0.60 0.57 0.55 0.53

0.75 0.69 0.66 0.64 0.62 0.61

0.78 0.74 0.72 0.70 0.68 0.67

used in a purely additive manner to formulate a ration of desired NEmg content, without incurring any significant error. This system was adopted by the U.K. as a solution to the problem of ration formulation for growing and fattening beef cattle in M.A.F.F. Technical Bulletin 33 (M.A.F.F., 1975, pp. 9-12 ). Van Es and his co-workers in the E.A.A.P. Feed Evaluation Working Group, who were concerned to have a single NE value for growing animals, decided after consideration of the variation in kmg as affected by APL and q (see Table II), on proposition of the French colleagues to choose a single level of APL, 1.5, at which to calculate NEmg values. This is equivalent to formulating for a liveweight gain of about 0.9 kg day-1 (van Es, 1978) for animals of any liveweight in various breeds, since APL values vary relatively little with the animars liveweight. This is because increases in maintenance energy requirements are paralleled by an increased energy content of the liveweight gain made by heavier animals. Having decided to use this simplification, deviations for lower and higher liveweight gains were allowed for by correcting the net energy requirements accordingly. An alternative proposal was to use NEl values at low levels of APL ( and liveweight gain) for rearing lactating cattle where the values for king approximate to those for kl ( see Table II). Table III compares the energy requirements of a 600-kg dairy cow at 4 levels of production in the various countries. A similar comparison for bulls gaining 1 kg day- 1 at 3 different levels of body weight is presented in Table IV.

Plane of nutrition effect McHardy's general theory was applied by him to the original A.R.C. (1965) ME model, which included a correction factor which depended on a definition of plane of nutrition (FL) in terms of ME intake. Obviously APL is closely correlated to multiples of maintenance ME, so that the expression (eqn. (6))

TABLE III Energy requirements for a 600-kg cow producing 4%-fat milk, calculated for the different energy systems No. in Appendix

Country

System

Unit

Maintenance

Milk yield day -1 (kg) 10

1 3 4

11 12 13 14 15 16 17 18

F.R.G. Denmark (DK) Norway (N) and Finland (SF) G.D.R. Sweden (S) U.K. (GB) U.S.A., Israel (US) Ireland (IRL) The Netherlands and Belgium France F.R.G. (D) and Austria Greece (GR) Switzerland ( CH ) Yugoslavia (YU) Italy Hungary (H) Rumania

19 19

U.S.S.R. (a) (SU) U.S.S.R. (b) (SU)

5 6 7 8 9 10

20

30

Starch equivalent Scandinavian feed unit Fattening feed unit

SEK (g) SFU (DK) (kg) FFU (kg)

3168 4.0 4.6

5918 8.0 8.6

8668 12.0 12.6

11418 16.0 16.6

Net energy fattening Metabolizable energy Metabolizable energy Net energy lactation Metabolizable energy Feed unit for milk

EFr (g) ME(S) (Mcal) ME (GB) (MJ) NEL ( US ) (Mcal) ME ( IRL ) (MJ) VEM (g)

3152 14.7 63 9.7 63 5013

6002 26.7 116 17.1 116 9486

8852 38.7 169 24.5 169 14105

11702 50.7 222 31.9 222 18869

Unit~ fourag~re lait Net energy lactation Net energy lactation Netto Energie Milch Net energy milk Unith foraggere Net energy lactation Unitatilor nutritive la rumetagoare Oat feed unit Metabolizable energy

UFL (kg) NEL(D) (MJ) NEL(GR) (MJ) NEL(CH) (MJ) NEL(YU) (MJ} UF (kg) NEL (H) (MJ) UN (kg)

5.0 35.5 35.5 35.5 35.5 5.0 40.6 3.7

9.3 67.2 67.2 66.9 66.5 9.3 71.5 6.7

13.6 98.9 98.9 98.3 97.5 13.6 102.5 9.7

17.9 130.6 130.6 129.7 128.5 17.9 133.5 10.7

OFU (kg) ME (SU) ( M J)

5.1 65

10.1 125

15.1 177

21.2 237

bO

t~ bD

TABLE IV Energy requirements for growing bulls gaining 1 kg d a y - 1, calculated for different European energy systems No. in Appendix

Country

1 2 3 4 5 6 7 9 10

F.R.G. and Austria Belgium Denmark (DK) Norway and Finland G.D.R. Sweden (S) U.K. (GB) Ireland (IRL) The Netherlands

11 13 14 15

France Greece Switzerland (CH) Yugoslavia (YU)

16 17

Italy Hungary

18

Rumania

19 19

U.S.S.R.(a) (SU) U.S.S.R.(b) (SU)

System

Starch equivalent Starch equivalent Scandinavian feed unit Fattening feed unit Net energy fattening Metabolizable energy Metabolizable energy Metabolizable energy Feed unit for growth and fattening Unitd fourag~re viands Modified starch value Netto Energie Mast Net energy for growth and fattening Unith foraggere Net energy for beef Unitatilor nutritive la rumetagoare Oat feedunit Metabolizable energy

Unit

Liveweight (kg) 200

400

SEK (g) S E ( N L ) (kg) S F U ( D K ) (kg) FFU (kg) EFr (g) M E ( S ) (Mcal) M E ( G B ) (MJ) ME(IRL) (MJ) VEVI (g)

2800 3.5 3.5 3.8-4.0 2313 58 56 56 4100

4300 4.9 5.8 5.8-6.0 3830 88 93 93 7400

UFV (kg) MSV (g) NEV(CH) (MJ) NEM (YU) (MJ)

3.8 3500 28.5 27.9

6.1 5500 43.8 44.8

8.2 6500 57.9 60.2

UFV (kg) NEm and NEg (MJ) UN (kg)

3.8 28.1

6.1 47.2

8.2 64.1

3.3

4.8

6.2

OFU (kg) ME (SU) (MJ)

6.6 55.0

9.1 85.0

notavailable notavailable

600

58OO 6.4 9.7 5034 115 114 114 1O500

227

above can be modified to accomodate plane of nutrition correction as well if desired. APL and FL are correlated by

APL=km+kg ( F L - 1) km

(7)

The Dutch/Swiss/Belgian systems for growing cattle do not include a variable plane-of-nutrition correction factor in the calculation of NEmg. In fact a correction should be included in these beef systems, but it was decided not to do so because the correction factor would be very small, fluctuating between 0.996 and 0.986 for FL between 1.2 and 1.8, respectively. However in the case of dairy cattle, a correction of 1.8% per multiple of maintenance was applied in the Dutch/Swiss/Belgian systems, and an average plane of nutrition of 2.38 × maintenance (requirement of a 550-kg cow producing 15 kg FCM) assumed. All NE~ values are therefore corrected by 0.9752 to allow for this. This correction for plane of nutrition should be applied to the ration consumed. Therefore a fixed level is chosen to express the energy value and deviations from that level of feeding are taken into account in the standards both for dairy and beef cattle. Feeding trials have been used to test or derive these standards.

Measurement or calculation of metabolizable energy content of animal feeds Measurement of M E The accurate measurement of the ME of a feed requires the use of a respiration calorimeter to measure the methane production over a 24-hour period or longer. Calculation of ME as a constant proportion of DE Because of the high cost and limited availability of such facilities, approximations have been introduced, to calculate either methane energy from digested organic matter (Blaxter and Clapperton, 1965), or methane and urine energy as a constant fraction, 0.19 of digested energy, DE (Armstrong, 1964) ME=0.81 DE

(8)

Calculation of M E from digestible organic matter Since the organic matter of many cereals and forages has a GE of about 19 MJ kg -1, eqn. (8) above can be converted into a general conversion factor applicable to the results of nearly all digestibility trials and to in vitro results from the Tilley and Terry (1963) technique, i.e. M E (MJ kg -1 D M ) = 0 . 0 1 5 DOMD (g kg -1 DM)

(9)

Alternatively, the results of digestibility trials, where full Weende chemical analyses (XP, XL, XF, XX) (Henneberg and Stohmann, 1960) have been

228 TABLE V Equations used for the calculation of ME as an intermediary step or as a final equation in the system concerned (ME (in kJ kg-1 DM) =a.DXP+b.DXL+c.DXF+d.DXX+e). Country

System code

a

b

c

G.D.R. Sweden (S)

EFr ME(S) ME(GB) NE(D) NE(US) VEM

37.9 20.9/ 36.81 34.2 34.2 41.9

13.4 14.8 12.1 15.5

U.K. (GB) F.R.G. (D) U.S.A. The Netherlands (NL) Fodder maize products Other fresh or preserved green fodders Other feedstuffs France (F)

17.7 18.0/ 18.8' 15.2 15.2 18.6 15.5 20.1 15.9 23.9

15.5 14.2 37.7 39.7

15.5 14.2 13.8 20.0

UFL

d

e

12.8 15.9 12.8 15.9 3 18.6 18.6 -1883 15.5 14.2 ,.2 14.6 3 17.4 1

1SeeAppendix I of the report of van der Honing and Steg (1984). 2With exceptions. 3Minus mono- and disaccharides if > 8%. DXP, DXL, DXF and DXX are in g kg- 1DM. carried out on feed and faeces, can be used to predict M E c o n t e n t of feeds, using regression equations derived from the results of bot h chemical analyses and calorimetric measurements. M a n y are derived from the work at the Oskar Kellner Institute at Rostock, G.D.R. ( S c h i e m a n n et al., 1971 ). Examples of equations used in various countries are shown in Table V. T h e results of calculating M E values of feeds by the various equations are tab u lated in Table VI for about 30 c o m m o n feeds for ruminants. T h e y are also expressed as a percentage of t he value for barley in each different system.

Comparison of energy values from different systems and conversion between units Nearly all energy units, w h e t h e r starch equivalent or based on metabolizable energy values of feeds, as in the r ecent l y-i nt roduced systems, are derived from digestibility trials with sheep or cattle. Variations in the digestibility of animal feeds are large, varying from 35% for cereal straws to over 85% for maize grain, a greater t h a n 2-fold variation. N o t surprisingly, therefore, there is a high degree of correlation between units, when expressed as the correlation coefficient, r. Values greater t h a n 0.90 are usually found, statistically highly significant (Van der H o n i n g and Steg, 1984, Table I X ) . T h i s implies t h a t relatively small errors are incurred when converting from one unit to another, providing the correct equation is used (see below). T o assist the reader in

TABLE VI ME-values according to 7 systems ( see appendix ) in MJ kg ' and relative to barley ( % ) (for system codes see Table I ) Feedstuff

ME in system ( MJ k g - l DM )

ME in system relative to barley ( % )

EFr

ME(S)

ME(GB)

NEL(H)

NEL(US)

VEM

NEL(D)

EF t

ME(S)

ME(GB)

NEL(H)

NEL(US)

VEM

NEL(D)

Fresh grass: early cut Fresh grass: late cut Grass silage: unwilted Grass silage: unwilted late Wilted grass silage Wilted grass silage: mod. qual. Grass hay: good qual. Grass hay: mod. qual. Fresh alfalfa: early cut Fresh alfalfa: late cut Alfalfa hay: reed. qual. Maize silage: milky stage Maize silage: dough stage Wheat straw Barley straw Fodder beets Barley (grain) Maize (grain) Peas Wheat bran Maize gluten feed Beet pulp Beet molasses Cane molasses Brewers' grains Citrus pulp Tapioca Coconut expeller Coconut meal' Rapeseed meal' Soyabean meal' Fat (veg. origin)

12.1 10.2 10.5 9.1 10.5 9.3 10.0 8.8 9.8 8.6 8.4 10.1 10.6 5.8 6.5 12.6 12.9 13.7 13.3 11.2 12.9 11.8 12.1 10.4 11.2 12.6 11.9 13.8 11.7 11.4 14.0 35.9

12.0 10.1 10.0 8.6 10.1 8.8 9.9 8.6 9.7 8.5 8.3 9.9 10.5 5.6 6.3 13.1 13.4 14.2 13.9 11.5 13.3 12.1 12.6 10.9 10.9 12.8 12.5 14.0 12.1 11.9 14.6 34.9

11.7 10.1 10.4 9.0 10.4 9.1 9.9 8.8 9.5 8.4 8.2 10.3 10.9 5.8 6.5 13.3 13.4 14.3 13.3 11.2 12.7 12.3 12.7 11.2 10.6 13.1 12.8 13.4 11.5 10.8 13.1 32.5

11.8 10.3 10.5 9.3 10.5 9.3 10.1 9.0 9.7 8.7 8.5 10.4 10.8 6.2 6.9 12.8 12.9 13.7 13.0 10.9 12.5 12.1 12.1 10.7 10.6 12.8 12.2 13.3 11.4 10.6 13.0 32.3

12.7 10.8 11.1 9.6 11.1 9.6 10.5 9.2 10.0 8.8 8.6 10.9 11.4 5.7 6.6 13.9 14.0 15.0 14.1 11.6 13.5 13.1 13.1 11.2 ll.1 13.9 13.2 14.5 12.2 11.2 14.1 37.9

11.8 9.9 9.9 8.7 10.1 8.9 9.7 8.7 9.9 8.7 8.6 9.9 10.4 5.8 6.5 12.0 12.6 13.5 12.8 10.9 12.5 11.6 11.5 9.9 10.8 12.3 11.8 13.4 11.3 10.8 13.1 35.7

11.7 10.1 10.4 9.0 10.4 9.1 9.9 8.8 9.5 8.4 8.2 10.3 10.9 5.8 6.5 12.8 13.4 14.3 13.3 11.2 12.7 12.1 12.3 10.7 10.6 12.9 12.8 13.3 11.4 10.8 13.1 32.4

93.3 79.0 81.1 70.6 81.6 71.6 77.0 67.8 75.7 66.9 65.2 78.4 82.0 44.8 50.2 97.2 100.0 106.3 103.0 86.8 100.0 91.7 93.8 80.6 86.4 97.4 92.4 106.7 90.8 88.2 108.1 278.2

89.2 74.9 74.0 64.1 74.9 65.8 73.3 64.3 72.2 63.5 61.9 73.4 77.9 41.5 46.6 97.1 100.0 106.0 103.4 85.9 98.6 89.9 94.1 81.2 81.0 95.1 92.9 104.3 89.9 88.7 108.8 259.9

87.7 75.3 77.5 67.6 77.7 68.3 73.8 65.5 70.7 62.9 61.4 77.0 81.3 43.2 48.6 99.7 100.0 107.1 99.5 83.9 95.3 91.6 95.0 83.8 79.5 97.9 96.0 99.9 86.1 80.8 97.9 242.7

91.8 80.2 81.8 72.2 81.9 72.5 78.2 70.0 75.0 67.4 65.9 80.5 84.1 47.9 53.6 99.7 100.0 106.7 100.8 84.9 97.2 94.3 94.4 82.8 82.1 99.9 95.0 103.2 88.9 82.7 100.7 251.1

90.7 77.5 79.3 68.4 79.5 68.8 75.2 66.0 71.6 63.0 61.4 77.9 82.0 40.8 47.3 99.7 100.0 107.6 100.9 82.8 96.8 93.5 93.6 80.5 79.6 99.8 94.3 103.6 87.4 80.3 100.8 271.5

93.1 87.7 78.6 75.3 78.3 77.5 69.1 67.6 79.6 77.7 70.4 68.3 76.9 73.8 69.0 65.5 77.9 70.7 68.9 62.9 67.6 61.5 78.4 77.0 82.6 81.3 46.1 43.3 51.6 48.6 94.7 96.0 100.0 100.0 106.9 107.1 101.5 99.6 86.1 83.9 98.9 95.3 91.9 90.9 90.7 91.7 78.3 80.3 85.2 79.5 97.6 96.8 93.5 96.0 105.7 99.4 89.2 85.5 85.1 80.8 103.7 97.9 282.5 242.8

Average ( N = 3 2 ) SD (N-=32)

11.7 4.9

11.7 4.8

11.6 4.3

11.5 4.2

12.3 5.2

11.4 4.8

11.5 4.3

90.4 37.6

87.3 35.7

86.7 32.4

89.6 32.7

88.2 37.1

~D

1Solvent extracted.

90.0 38.1

86.3 32.4

t,D

TABLE VII

O

Energy values according to different feed evaluation systems (for system codes see Table I) Feedstuff

SEK

Fresh grass: early cut 700 Fresh grass: late cut 575 Grass silage: unwilted 602 Grass silage: unwilted late 503 Wilted grass silage 564 Wilted grass silage rood. qual. 470 Grass hay: good qual. 501 Grasshay: mod. qual. 414 Fresh alfalfa: early cut 536 Fresh alfalfa: late cut 446 Alfalfa hay: med. qual. 365 Maize silage: milky stage 594 Maize silage: dough stage 630 Wheat straw 143 Barley straw 203 Fodder beets 634 Barley (grain) 817 Maize (grain) 890 Peas 825 Wheat bran 567 Maize gluten feed 776 Beet pulp 615 Beet molasses 548 Cane molasses 514 Brewers'grains 575 Citrus pulp 747 Tapioca 800 Coconut expeller 855 Coconut meal' 710 Rapeseed meal 1 644 Soyabean meal' 804 Fat (veg.origin) 2287 Average (N--32) SD (N--32) ~Solvent extracted.

651 345

SE(NL)

SFU(DK)

FFU

TDN EFt

ME(S)

ME(GB)

NEL(H)

NEL(US)

VEM

UFL

NEL(D)

673 555 572 479 537 448 484 402 522 436 358 575 614 135 194 631 821 925 800 567 808 709 589 545 631 755 792 857 677 598 787 2847

0.974 0.722 0.745 0.650 0.757 0.670 0.715 0.567 0.716 0.561 0.541 0.725 0.760 0.196 0.276 0.919 1.129 1.177 1.212 0.935 1.088 0.941 0.952 0.799 0.855 1.012 1.067 1.293 1.073 1.075 1.339 3.050

0.900 0.697 0.741 0.658 0.746 0.664 0.694 0.565 0.642 0.510 0.494 0.749 0.790 0.204 0.289 0.967 1.142 1.220 1.146 0.911 1.040 0.969 0.968 0.856 0.801 1.067 1.143 1.260 1.014 0.930 1.126 3.267

78.1 639 68.2 561 69.5 587 61.4 517 69.7 582 61.6 513 66.5 545 59.5 487 63.8 510 57.3 459 56.1 445 68.5 570 71.6 591 40.7 336 45.6 377 84.8 678 85.0 693 90.7 762 85.7 671 72.2 607 82.6 693 80.2 637 80.3 635 70.4 567 69.8 633 84.9 707 80.8 650 87.7 797 75.6 612 70.3 548 85.6 643 213.5 2855

2.87 2.41 2.38 2.06 2.41 2.11 2.36 2.07 2.41 2.04 1.99 2.36 2.50 1.34 1.50 3.12 3.21 3.40 3.32 2.76 3.17 2.89 3.02 2.61 2.60 3.06 2.99 3.35 2.89 2.85 3.50 8.35

11.72 10.07 10.37 9.04 10.39 9.13 9.86 8.76 9.46 8.41 8.22 10.29 10.87 5.78 6.49 13.33 13.37 14.32 13.31 11.21 12.74 12.25 12.70 11.20 10.63 13.09 12.83 13.35 11.51 10.81 13.09 32.46

8.190 7.088 7.233 6.331 7.255 6.353 6.899 6.120 6.598 5.875 5.741 7.121 7.466 4.028 4.573 8.935 8.958 9.592 9.036 7.533 8.691 8.423 8.435 7.333 7.266 8.947 8.490 9.258 7.912 7.322 9.024 23.259

1.793 1.550 1.584 1.384 1.587 1.390 1.509 1.338 1.443 1.284 1.254 1.557 1.633 0.877 0.996 1.957 1.964 2.103 1.980 1.648 1.904 1.845 1.847 1.606 1.590 1.960 1.860 2.030 1.732 1.602 1.977 5.112

1026 832 829 712 845 729 810 712 823 710 694 858 915 444 506 1084 1126 1221 1137 928 1097 1029 1036 877 899 1108 1063 1179 971 904 1147 3524

1.022 0.845 0.878 0.743 0.872 0.752 0.841 0.730 0.713 0.685 0.825 0.885 0.435 0.502 0.965 1.148 1.224 1.147 0.911 1.106 1.035 1.096 0.923 0.830 1.146 1.050 1.140 0.965 0.918 1.176 2.938

7.18 6.00 6.31 5.35 6.27 5.39 5.87 5.11 5.54 4.83 4.69 6.18 6.62 3.11 3.56 8.39 8.55 9.30 8.43 6.81 7.94 7.71 7.99 6.88 6.25 8.33 8.35 8.28 7.00 6.43 8.10 21.95

666 436

0.922 0.471

0.912 0.501

659 2.81 413 1.14

11.60 4.34

7.978 3.095

1.747 0.682

992 499

0.977 0.405

7.15 3.09

76.2 27.8

0.820

231 making inter-conversions, tables of values for 30 common animal feeds, expressed in each of the units in use in Europe have been calculated. Table VI shows the results of ME values, calculated from digestible nutrients according to Table V. Since the values for the ME of barley grain vary between systems, the values are also tabulated in percentage terms, with the energy value of barley in the relevant unit set at 100 to compare between systems. The energy values of 30 feeds expressed in units of the various systems are given in Table VII. To allow comparison between the systems all these values are also scaled on the respective value of barley. This permits the use of specific factors of conversion between the systems for each particular feed. These conversion factors are not constant for the various feeds. Although constant conversion factors between systems do not exist, one can use average conversion factors or a regression equation derived from a great variety of feeds and accept at the same time minor inaccuracies. Average conversion factors are given in Table VIII. An even more accurate conversion requires the derivation of the appropriate regression equation, because both the slope and intercept need to be known in order to convert accurately at the extremes. These can be derived from the information tabulated, but space does not permit their inclusion here.

Description of European energy systems The authors have attempted to summarize the essential features of the energy systems at present in use in Europe. Use has been made of the published proceedings of a C.E.C.-funded seminar (C.E.C., 1980) on the energy and protein standards for beef cattle, particularly of the survey of energy feeding standards therein (Neimann-S~rensen, 1980), and of a review of feed evaluation systems for dairy cows, (de Brabander et al., 1983; van der Honing and Steg, 1984). Details of other systems have been obtained by correspondence with scientists, using the good offices of the E.A.A.P. Secretary General to establish contact. The diversity and complexity of the systems described may strike the reader as confusing and unnecessary. It is necessary, however, to remember the diverse range of crops, feeds and byproducts in each country, and also the indigenous native breeds of cattle and feeding practices which are of a longestablished nature. If workers in various countries have felt it necessary to adjust or modify published standards, to ensure a good fit to their own feeding trials, this is difficult to criticize on practical grounds, whatever difficulties it presents to the reviewer or to the peripatetic European nutritional adviser. The individual systems are described in the Appendix on energy systems for ruminants.

t~

TABLE VIII

tO

Energy values according to different feed evaluation systems relative to barley (for system codes see Table I ) Feedstuff

SEK

SE(NL)

S F U ( D K ) FFU

TDN EFr

ME(S)

ME(GB)

NEL(H)

N E L ( U S ) VEM UFL

Fresh grass: early cut Fresh grass: late cut Grass silage: unwilted Grass silage: unwilted late Wilted grass silage Wilted grass silage: mod. qual. Grass hay: good qual. Grass hay: mod. qual. Fresh alfalfa: early cut Fresh alfalfa: late cut Alfalfa hay: reed. qual. Maize silage: milky stage Maize silage: dough stage Wheat straw Barley straw Fodder beets Barley (grain) Maize (grain) Peas Wheat bran Maize gluten feed Beet pulp Beet molasses Cane molasses Brewers grains Citrus pulp Tapioca Coconut expeller Coconut meal I Rapeseed meal 1 Soya bean meal ~ Fat (veg.origin)

85.7 70.4 73.7 61.6 69.0 57.5 61.3 50.7 65.6 54.6 44.7 72.7 77.1 17.5 24.8 77.6 100.0 108.9 101.0 69.4 95.0 75.3 67.1 62.9 70.4 91.4 97.9 104.7 86.9 78.8 98.4 279.9

82.0 67.6 69.7 58.3 65.4 54.6 59.0 49.0 63.6 53.1 43.6 70.0 74.8 16.4 23.6 76.9 100.0 112.7 97.4 69.1 98.4 86.4 71.7 66.4 76.9 92.0 96.5 82.5 72.8 95.9 346.8

86.3 64.0 66.0 57.6 67.1 59.3 63.3 50.2 63.4 49.7 47.9 64.2 67.3 17.4 24.4 81.4 100.0 104.3 107.4 82.8 96.4 83.3 84.3 70.8 75.7 89.6 94.5 114.5 95.0 95.2 118.6

91.9 80.2 81.8 72.2 82.0 72.5 78.2 70.0 75.1 67.4 66.0 80.6 84.2 47.9 53.6 99.8 100.0 106.7 100.8 84.9 97.2 94.4 94.5 82.8 82.1 99.9 95.1 103.2 88.9 82.7 100.7

89.4 75.1 74.1 64.2 75.1 65.7 73.5 64.5 75.1 63.6 62.0 73.5 77.9 41.7 46.7 97.2 100.0 105.9 103.4 86.0 98.8 90.0 94.1 81.3 81.0 95.3 93.1 104.4 90.0 88.8 109.0

87.7 75.3 77.6 67.6 77.7 68.3 73.7 65.5 70.8 62.9 61.5 77.0 81.3 43.2 48.5 99.7 100.0 107.1 99.6 83.8 95.3 91.6 95.0 83.8 79.5 97.9 96.0 99.9 86.1 80.9 97,9

270.2

78.8 61.0 64.9 57.6 65.3 58.1 60.8 49.5 56.2 44.7 43.3 65.6 69.2 17.9 25.3 84.7 100.0 106.8 100.4 79.8 91.1 84.9 84.8 75.0 70.1 93.4 100.1 110.3 88.8 81.4 98.6 286.1

242.8

91.4 79.1 80.7 70.7 81.0 70.9 77.0 68.3 73.7 65.6 64.1 79.5 83.3 45.0 51.0 99.7 100.0 107.1 100.9 84.1 97.0 94.0 94.2 81.9 81.1 99.9 94.8 103.4 88.3 81.7 100.7 259.6

91.3 78.9 80.7 70.5 80.8 70.8 76.8 68.1 73.5 65.4 63.8 79.3 83.1 44.7 50.7 99.6 100.0 107.1 100.8 83.9 96.9 93.9 94.0 81.8 81.0 99.8 94.7 103.4 88.2 81.6 100.7 260.3

91.1 73.9 73.6 63.2 75.0 64.7 71.9 63.2 73.1 63.1 61.6 76.2 81.3 39.4 44.9 96.3 I00.0 108.4 101.0 82.4 97.4 91.4 92.0 77.9 79.8 98.4 94.4 104.7 86.2 80.3 101.9 313.0

79.8 42.3

81.2 53.2

81.6 41.8

79.8 43.9

86.7 32.4

89.1 34.5

88.9 34.7

88.2 44.3

Average (N = 32 ) SD ( N = 3 2 ) 1Solventextracted.

104.4

92.2 81.0 84.7 74.6 84.0 74.0 78.6 70.3 73.6 66.2 64.2 82.3 85.3 48.5 54.4 97.8 100.0 110.0 96.8 87.6 100.0 91.9 91.6 81.8 91.3 102.0 93.8 115.0 88.3 79.1 92.8

251.2 412.0 260.1

89.6 32.7

95.2 59.6

87.5 35.7

NEL(D)

89.0 84.0 73.6 70.2 76.5 73.8 64.7 62.6 76.0 73.3 65.5 63.0 73.3 68.7 63.6 59.7 71.4 64.8 62.1 56.5 59.7 54.9 71.9 72.2 7 7 . 1 77.4 37.9 36.4 43.7 41.6 84.1 98.1 100.0 100.0 106.6 108.8 99.9 98.5 79.4 79.6 96.3 92.9 90.2 90.2 95.5 93.5 80.4 80.5 72.3 73.1 99.8 97.4 91.5 97.7 99.3 96.8 84.1 81.8 80.0 75.2 102.4 94.7 255.9 256.7 85.1 35.3

83.6 36.2

233

Approach to a common energy feed unit F o r p l a n n i n g p u r p o s e s o n a large scale in a region, a c o u n t r y or a n u m b e r o f countries, t h e r e is a n e e d for a c o m m o n u n i t for t h e n u t r i t i v e value o f feed resources to be able to p r e d i c t t h e p o t e n t i a l for a n d scale of a n i m a l p r o d u c t i o n . A u n i t b a s e d o n e n e r g y value is v e r y suitable, a l t h o u g h t h e p r o t e i n resources m i g h t also be a vital e l e m e n t o f such p l a n n i n g . T h e e n e r g y available to t h e a n i m a l will be used for d i f f e r e n t p u r p o s e s e.g. m a i n t e n a n c e , milk yield, wool p r o d u c t i o n , m e a t p r o d u c t i o n , egg p r o d u c t i o n etc., b u t with differences in efficiencies o f utilization of digestible or m e t a b o l izable energy. T h u s it is a p p r o p r i a t e to use M E as a c o m m o n base a n d c o n v e r t b y m e a n s of t h e efficiency of utilization to t h e d i f f e r e n t t y p e s of a n i m a l production. T o e s t i m a t e t h e a n i m a l p r o d u c t i o n p o t e n t i a l which is possible with a c e r t a i n q u a n t i t y of feed, r e l e v a n t average values could be used regardless of t h e f o r m u l a t i o n of t h e r a t i o n a n d l i m i t a t i o n s to feed c o n s u m p t i o n . F o r p l a n n i n g on a f a r m scale or for individual animals, however, one needs a precise calculation w i t h m u c h m o r e d a t a for a d e q u a t e prediction. S t u d y i n g the i n f o r m a t i o n in this c h a p t e r it is clearly n e c e s s a r y to define a u n i t which can easily be u n d e r s t o o d b y non-specialists. T h u s we p r o p o s e as a c o m m o n e n e r g y feed u n i t t h e q u a n t i t y o f M E in 1 kg of barley. T h e average M E of b a r l e y in t h e tables o f t h o s e c o u n t r i e s or systems, w h e r e m e a s u r e m e n t s TABLE IX ME and NE values of barley for dairy cattle presented in some national feed tables (I) or calculated using standardized composition and digestibility coefficients (II) (van der Honing and Steg, 1984) Country/system

Denmark, SFU (DK) France, UFL F.R.G., NEL (D) G.D.R., EFr Hungary, NEL (H) The Netherlands, VEM Rumania, UN (RO) Sweden, ME (S) Switzerland, NEL (CH) U.K., ME (GB) U.S.A., Israel, NEL (US) Average1 SD

ME in MJ kg-1 DM

NE in MJ kg- 1 DM

I

II

I

II

12.7 13.26 13.07 13.07

13.5 12.62 12.8 13.56

13.13 13.36 12.92 12.9 12.65 13.44 12.65 13.37 13.96

9.1 8.40 8.33 7.35 7.76 7.77 7.80 7.99

8.91 8.31 8.55 7.28 8.96 7.76 7.76 8.22

13.07 + 0.39

13.18 _+0.45

7.84 ___0.35

8.26 _+0.46

12.65

ISFU and EFr-values, which are based on fattening animals, are omitted.

234 TABLE X Quantity of barley dry matter (kg) to meet the energy requirements of a 600 kg cow, producing 20 kg of energy corrected milk without body energy gain or loss Country/system

Denmark, SFU (DK) France, UFL F.R.G., N E L ( D ) G.D.R., EFr The Netherlands, VEM Sweden, M E ( S ) Switzerland, NEL (CH) U.K., M E ( G B ) U.S.A., Israel, NEL (US)

Requirement ( MJ )

Energy value of barley (MJ k g - 1 DM)

ME

ME

NE 94.7 98.4 98.9 92.9 97.4

161.9

AverageI SD

NE 9.10 8.40 8.33 7.35 7.76

13.5 98.3

169.0 171.2

Quantity of barley required (kgDM)

102.5

7.80 12.8 13.56

7.99

10.41 11.71 11.87 12.65 12.55 11.99 12.60 13.20 12.63/12.832 12.42 + 0.52

1SFU and EFr omitted (see Table IX). 212.63 from ME, 12.83 from NE.

in vivo have been performed, is close to 13 MJ ME kg -1 DM of barley (Table IX). There is some variation between countries owing to small differences in the composition and digestibility of nutrients in barley. As the DM content of barley can vary, it is necessary to define this energy feed unit on a DM basis, although it can be converted to 11.2 MJ ME in 1 kg barley with 86% DM. Variations in the ME value of barley may be compensated for by differences in the requirements of the animal. Therefore we calculated the amounts of barley which would be necessary to meet the requirements of a cow and a bull with standardized performance, notwithstanding that the farmer would not feed barley as the only feedstuff in the ration for ruminants. Table X shows that the theoretical quantity of barley to meet the requirements of a cow (600 kg liveweight, 20 kg energy-corrected milk) varies between 11.7 kg DM and 13.2 kg DM (average 12.4 kg DM), omitting those values which are based on fattening values. The calculation for a growing bull (400 kg, gaining 1000 g day- 1) shows a larger variation (5.0-6.9 kg DM) in quantity of barley required than for the cow (Table XI). This is understandable because energy per kg liveweight gain varies widely across Europe owing to differences in breed and feeding system.

235 TABLE XI

Quantity of barley dry matter to meet the energy requirement of a growing bull of 400 kg liveweight, gaining 1000 g d a y Country/system

Requirement (MJ)

ME Belgium, SE (NL)

Quantity of barley required

(MJ kg -1 DM)

{kg DM)

ME

49.0 45.8 47.3 43.0 40.2 47.2 51.1 47.0 50.2

Denmark, SFU ( D ) France, UFL F.R.G., SEK G.D.R., EFr Hungary (NEro; NE~) The Netherlands, VEVI Norway, Finland, FFU Rumania, UN (RO) Sweden, ME (S) Switzerland, NEV (CH) U.K., ME (GB)

NE

Energy value of barley

88.0

8.21 9.07 9.00 8.00 7.35 8.20; 5.48 8.47 7.89 7.77 13.5

43.8 81.8

NE

8.50 12.8

6.0 5.0 5.3 5.4 5.5 6.9 6.0 6.0 6.5 6.5 5.2 6.4

SYSTEMS FOR PROTEIN EVALUATION OF FEEDS AND PROTEIN REQUIREMENTS OF RUMINANTS

Introduction In the last decade, a number of new protein requirement systems have been published from research workers in the U.S.A. and Europe. These introduce new concepts and require new methods for the evaluation of the protein content of ruminant feeds. They are replacing the Digestible Crude Protein (DXP) system which has been in use in Europe for nearly a century. Crude protein is measured in the laboratory as total nitrogen ( N ) , multiplied by 6.25, the average ratio of protein to N in animal feeds. Non-protein nitrogen compounds ( N P N ) , such as urea, ammonia and nitrate, are included in this method of calculation. Since the ruminant is able to utilize such N P N compounds to some degree in the rumen, this introduces variability on the responses to diets which contain them, when they are evaluated by their D X P content. Attempts have been made to adjust for this by assigning a value of only one half to crude protein present as NPN. The responses obtained from varying the D X P intake of ruminants have been shown to be influenced by the source of the crude protein and by the energy supply as well as other factors. Accurate D X P requirements can only be determined by feeding trials for each class of animal, level of production

236 and basal forage fed. Advisers vary in their interpretation and use of DXP allowances, using their experience of particular animal production systems and feeds. The DXP system ignores the central role of microbial fermentation in the 2-stage digestive system of ruminants. Responses to changes in dietary intake which may be due to microbial responses in the rumen, or to the nature of the undegraded feed particles undergoing digestion in the abomasum and intestines of the animal, are not explained satisfactorily by changes in DXP intake.

Digestion and absorption of protein in ruminants Ruminants are so called because they have a 4-compartment stomach, the largest compartment, 85% in volume, being the rumen. This contains a specialized microbial population, both bacteria and protozoa, which digest the feed eaten, producing metabolites of use to the animal. Digestion of cellulose, starch and sugar in the feed give rise to large amounts of volatile fatty acids, acetic, propionic and butyric acids, which are absorbed and used by the animal. Much of the feed protein is broken down or "degraded" via peptides and amino acids to ammonia. These are then partly used for the synthesis of microbial protein, which cannot be absorbed in the rumen. On average about 65 % of the digestible organic matter in a diet will be "degraded" in the rumen. The contents of the rumen are continually being passed on to the fourth compartment, the abomasum, and thence to the intestines, where a non-ruminant type of digestion by the use of secreted enzymes takes place. The digesta, however, consists of a mixture of "undegraded" feed protein and microbial protein, with the latter being 50-70% of the total protein flow. Microbial protein has an amino-acid composition which is generally well suited to the animals' needs. The protein actually digested by the ruminant animal therefore differs considerably from the composition of the protein in the original diet. Because of this ability, ruminants can utilize feed resources containing poorer quality protein than other farm animals, but still produce high-quality proteins such as milk and meat. Ruminants can also utilize sources of non-protein nitrogen, such as urea and ammonia, because these can enter the synthetic pathways of the rumen microbes, provided adequate energy is available to the microbes from carbohydrate degradation. This interdependence of energy supply and microbial protein synthesis is central to the protein metabolism of ruminants. The DXP system contains no such relationship.

New systems: concepts and definition of terms General A total of six new national protein-requirement systems have been published since 1977. In chronological order, these are: (1) the British R D P / U D P system

237 of Roy et al. (1977), subsequently published as A.R.C. (1980) and revised A.R.C. (1984) ; (2) the French "Protein digested in the Intestine" or PDI system, I.N.R.A. (1978, revised 1987); (3) the Swiss ("Absorbable Protein in the Intestine" or API system of Landis (1979, 1984), derived from the French PDI system; (4) the F.R.G. "Crude Protein Flow at the Duodenum" system; Rohr et al., Anschuss fiir Bedarfsnormen (1986), see Addendum; (5) the Nordic AAT-PBV system, based on "Amino acids truly absorbed in the small intestine", AAT and "Protein balance in the tureen", PBV; N K J / N K F (1985); (6) the U.S.N.R.C. "Absorbed Protein", AP system, based on absorbed true protein requirements, N.R.C. (1985).

Terminology All the new systems are based on the same concepts, illustrated diagrammatically in Fig. 2, and in tabular form in Table XII, identified by the conventional country code letters. The essential elements of all systems are outlined in the following section, using mainly the terminology of Waldo and Glenn (1982a). (a) Degraded dietary crude protein, RDP. This part of crude protein will be metabolized by rumen microbes to peptides and ammonia. Most of it may be converted to microbial crude protein ( M X P ) . (b) Microbial crude protein, MXP. The synthesis of microbial protein depends on sufficient energy being available to the microbes mainly from the degradation of carbohydrates in the feed. It is usually postulated that MXP can be predicted from energy intake expressed as ME or NE as MJ day -1, or alternatively from digestible organic matter (DOM) as kg day-1. ME or NE and DOM are correlated, depending upon the nature of the feed. As a mean value, 1 kg DOM could be taken to be equivalent to 15.6 MJ ME or 9.4 MJ NE~. The Nordic system is unique in predicting MXP from digestible carbohydrates. This is because fat and protein are not sources of energy for rumen microbes. (c) Efficiency of conversion of RDP to MXP, MXP/RDP. Most systems define an efficiency of capture of N from feed protein into microbial crude protein as being 1.0 when XP intake is limiting. Only the U.S.N.R.C. system gives a lower maximal efficiency, 0.9. When XP intake is in excess, efficiency is < 1, but MXP synthesis is then limited by energy supply. The efficiency of capture of N P N is stated to be only 0.8 by A.R.C. (1980). (d) Undegraded dietary crude protein. The remainder of the feed crude protein that is not degraded by microbial action in the rumen, passes unchanged to the abomasum and intestines. It is there subjected to enzymatic digestion, resulting in further absorption of amino acids into the animal body. (e) Proportion of true protein in microbial crude protein, M T P / M X P . Microbial crude protein contains a significant proportion of nucleic acid N, which cannot be used by the animal to synthesize tissue proteins or milk. The pro-

238 Crude protein intake (IXP)

Energy intake I (as HE or DOM or DCHO)

I

Ef feccive degradability, p

HXPIME

or MXPIDOM

l-p

Degraded dietary XP (RDP)

8.4 - 10.3 g/Md .13 - .16

I Undegraded dietary i XP (UDP) I

I

or MXP/DCHO .179

~e/ZDP,

, o.8-1.o

I

l -I

'

Microbial crude protein (~c~)

~/~'

i I

1

I

'I

MTPIHXP, 0.7-0.8

I

l I

[

_J

Microbial true protein

~///~//~

(MTp)

[

I

)

I DUDP/UDP, 0.6-0.9 ]

L

DMTP/MTP, 0.7-0.9

Digestible ~P

,....,F+~,lXP I

,

-

p'/~

D

~J

/

~

MFN related to DMI

I Metabollc faecal N (MFN)

I

I

Total absorbed amlnoacids (TAA)

I

kn, 0.6-0.8 (u~) Tissue

proteins:

maintenance,

l a c t a t i o n , growth

- indicates losses since the preceeding step

Fig. 2. Scheme showing terms used to describenew ruminant protein systems and how they relate to one another (see also Table VII).

239 TABLE XII Factors in the utilization of protein by ruminants Factor

Microbial crude protein/ degraded dietary crude protein Microbial crude protein/digestible organic matter Microbial crude protein (g MJ -1 metabolizable energy) Microbial crude protein/digestible carbohydrate Microbial true protein/microbial crude protein Digestible microbial true protein/microbial true protein Digestible microbial true protein/microbial crude protein Digestible undegraded dietary protein/ undegraded dietary protein Metabolic faecal protein/feed dry matter Metabolic faecal protein/indigestible feed dry matter Tissue protein (amino acid)/absorbed amino acids: Maintenance Lactation Growth Wool/hair

Protein system GB

F1

CH

D

NKJ/ NKF

US

0.81.0

1.0

1.0

0.95

V

0.9

0.130

0.135

0.135

0.161

8.4

8.7

8.7

10.1b

10.3

9.6c

n.s.

n.s.

n.s.

n.s.

0.179

n.s.

0.80

0.80

0.80

0.73

0.70

0.80

0.85

0.70

0.70

0.90

0.85

0.80

0.68

0.56

0.66

0.80

0.66

0.60 0.530.702

0.64

0.85

0.56 0.600.952

n.s.

n.s.

n.s.

0.0182

n.s.

n.s.

n.s.

0.79 0.80 0.80 0.80

(M) 0.67 0.60 n.s.

(M) 0.67 0.60 n.s.

0.165

0.14a

0.80

n.s.

n.s.

n.s.

n.s.

0.09

0.80 0.80 0.80 n.s.

(M) 0.75 n.s. n.s.

0.67 0.65 0.50 0.15

~System revised late 1987, see Addendum to Appendix. 2Variation according to class of feed. n.s. = Not stated; 000 (figures underlined) -- an approximation; V = variable; (M) -- maintenance requirement estimated from N-balance or feeding trials. For a, b, c, see Appendix for full relationship. p o r t i o n M T P / M X P is s t a t e d to be e i t h e r 0.7 or 0.8, d e p e n d i n g on t h e s y s t e m under consideration. (f) Digestibility of m i c r o b i a l t r u e protein, D M T P / M T P . Values for t h e prop o r t i o n of M T P digested a n d a b s o r b e d in t h e i n t e s t i n e s v a r y f r o m 0.7-0.9 in t h e d i f f e r e n t systems. (g) Digestibility o f u n d e g r a d e d d i e t a r y protein, D U D P / U D P . U n d e g r a d e d feed p r o t e i n varies in c o m p o s i t i o n a n d digestibility in t h e a b o m a s u m a n d intestines, d e p e n d i n g o n t h e origin a n d t r e a t m e n t o f t h e feed. N e v e r t h e l e s s , m o s t

240 systems assign a constant value of either 0.8 or 0.85 to this parameter. The Nordic system gives values of 0.53 for forages and 0.7 for concentrates, whilst the I.N.R.A. (1978) system values vary over the range 0.6-0.95, depending on the feed. (h) Efficiency of utilization of absorbed amino acids, kn. The efficiency of utilization of absorbed amino acids is stated in the various systems on the assumption that all absorbed amino acids are used specifically for protein synthesis in the organism. Non-specific use for other components of metabolism, such as fat synthesis, are not considered.

Measurement of protein degradability in ruminant leeds Laboratory methods of determining protein degradability have usually been based on measurements of protein solubility in buffer solutions (Henderikx and Martin, 1963; Burroughs et al., 1975; Crooker et al., 1978). Rumen liquor and purified bacterial-protease enzyme preparations have been used (I.N.R.A., 1978; Mahdevan et al., 1980), but the latter authors concluded that solubility or insolubility of protein is not of itself an indication of the protein's susceptibility to hydrolysis by rumen bacterial proteases. This view is now widely accepted, as a result of the use of the in situ dacron

1.0

L G

0.8

"~

i

0.6

0.4 0.2

F

0

TIME (t)

Fig. 3. Examplesof the relationshipbetweendegradabilityand time of incubation for 3 protein supplements. (G = Groundnutmeal;L = linseedmeal;F = fishmeal).

241 TABLE XIII Protein degradability values for ruminant feeds, after Madsen and Hvelplund (1985) and Rohr et al. (1985). (protein degradability, p, for an outflow rate, k, of 0.08 h- ~) Type of feed

Mean

SD

Group 1:p--0.40 (0.30-0.50) Blood meal Coconut meal Dried beet pulp Fish meal Maize grain Palmkernel meal

0.40 0.37 0.38 0.43 0.31 0.34

Group 2:p=0.55 (0.45-0.65) Dried brewers' grains Dried grass Cottonseed meal

0.49 0.54 0.56

Group 3:p=0.65 (0.55-0.75) Linseed meal Soya bean meal Meat and bone meal Molasses Maize silage Red clover silage

0.60 0.59 0.66 0.65 0.64 0.67

Group 4:p=0.75 (0.65-0.85) Barley grain Peas Rapeseed meal Sunflower meal Pasture grass Red clover Grass hay

0.70 0.77 0.68 0.73 0.70 0.76 0.74

0.07 0.04 0.06 0.05 0.11 0.03

Group 5:p=0.85 (0.75-0.95) Wheat Beans Fodder beet Grass silage Grass/clover silage

0.82 0.86 0.82 0.73 0.75

0.03

0.07 0.09 0.04 0.06

0.05 0.09

0.04 0.19 0.03

0.03 0.06 0.06

b a g t e c h n i q u e d e v e l o p e d b y O r s k o v a n d M e h r e z (1977). T h i s m e a s u r e s t h e loss of n i t r o g e n f r o m a s a m p l e of t h e feed p l a c e d in a d a c r o n b a g a n d s u s p e n d e d in t h e r u m e n for p e r i o d s o f u p to 72 hours. T h e zero t i m e v a l u e is o b t a i n e d b y w a s h i n g t h e b a g u n d e r cold w a t e r only. T y p i c a l r e s u l t s are p l o t t e d as s h o w n in

242

Fig. 3, and show the very different characteristics of some feeds. The proportions of soluble N, the rate of degradation and the amount not degraded differ between feeds. The average retention time in the rumen also affects the likely true degradability in vivo. In order to calculate a single parameter to use in the protein systems, Orskov and Mehrez used the exponential function

d g = a + b ( 1 - e -ct)

(1)

where dg = degradability; a = cold-water-soluble N; a + b = asymptote of curve, the potential maximum degradable N; c= rate of disappearance of N per hour; t = time in hours. Subsequent studies on outflow rates of feed particles from the rumen (Orskov et al., 1979), showed the necessity to correct for this factor. Rates vary from 0.02 h - 1 for animals at maintenance to 0.08 h - 1 for high producing dairy cows. This is done by substituting the constants fitted to the data by the use of eqn. (1) above, into eqn. (2) below to calculate the effective degradability, p, for the mean outflow rate h-1 from the rumen, k

p=a+bc/(c+k)

(2)

Because the dacron bag technique is an in vivo one and influenced by both type of animal and diet fed, standardization of the procedure is needed to get accurate results. Typical degradability values for some common feeds are shown in Table XIII. FUTURE DEVELOPMENTS IN FEED EVALUATION AND NUTRIENT REQUIREMENTS IN RUMINANTS

Analysis of feedstuffs The routine analysis of feedstuffs is still far from ideal (e.g. Weende analysis) and should be improved to measure well-defined components, in order to improve the quantification of the building blocks and energy sources which are utilized by the animal.

Information technology The scientific basis of protein and energetic feed evaluation systems is very important, particularly for application in practice, but farmers and feed manufacturers often focus their interest on accurate, but simple prediction methods for nutritive value. Moreover these methods should be quick and easy to execute. Developments in information technology have enabled the development of large databases, which contain a lot of accurately-measured data on energy, protein and other nutrients and their digestibilities from a wide range of feedstuffs.

243 Prediction of energy and protein values Energy and protein values of feedstuffs can be most accurately predicted from information on the digestibility of nutrients. The laborious and expensive nature of the technique required to measure digestibility coefficients with animals resulted in a search for alternatives to predict them from chemical analysis, which are still in use. Crude fibre predicts digestibility of organic matter ( doM ) in forages reasonably well if regression equations were derived for each type of forage. The van Soest analysis with detergents (ADF, NDF, ADL) aiming at a better description of the fibrous components, however, did not result in a successful improvement in the prediction of doM, mainly because the reproducibility and precision of these analyses (of ADL in particular) was rather poor (van Es, 1986). A subsequent trend was to imitate the ruminant's digestive processes in vitro, either with rumen liquor (Tilley and Terry, 1963) or with industriallyavailable enzymes. If sufficient precautions were taken to standardize for variation in the enzyme concentration of rumen liquor and for other factors (by using reference samples of known doM in vivo in each run) these methods result in a better prediction (van der Meer, 1984). These methods are still laborious, and require days of incubation before results can be obtained. This is also the case with "Menke's Gasbildungstest", where dOMhas to be derived from the amount of gas produced during incubation of a feed sample with rumen liquor (Menke et al., 1979). All these methods require careful calibration with sufficient samples with a known doM in vivo of the same feedstuff as is to be tested. A rapid prediction within a few minutes seems to be possible with reasonable accuracy by the method of near-infrared reflectance (NIR) spectroscopy, as was concluded at a C.E.C. seminar in Brussels and at a workshop at Braunschweig in 1985. This method is based on the absorption of near-infrared light (1100-2500 n m ) at various wavelengths dependent on the composition of the sample. The reflected light can be analysed and used to predict chemical composition. Even more than with the earlier methods, extensive calibration is required using a large set of samples of the type of feedstuffs to be tested of known composition or digestibility with a wide range of variation. From this calibration, regression equations are derived to predict with sufficient precision, in similar samples, the required parameter. In the beginning this method was used to predict the chemical composition of feeds, and digestible organic matter or protein was derived indirectly from that predicted chemical parameter. More recently, direct prediction of doM has been investigated and will be introduced in practice in the near future (van Es, 1986). One problem is the lack of sufficient samples of known doM in vivo to calibrate the NIR-method properly, but the idea is that additional samples with known doM in vitro can be used successfully as complementary information ( van Es, 1986).

244

Similar trends as with doM will certainly be utilized in the prediction of digestible protein. Besides techniques to predict from chemical analysis, or incubation with chemicals or enzymes to determine the protein solubility, in situ techniques are also used. In these methods some feedstuff in a small nylon bag is placed into the rumen for some time, or into the duodenum, to study degradation, or digestion, respectively. It is not yet known whether results from these studies can be used to calibrate the NIR equipment so that a rapid prediction of the protein quality of feeds can also be made.

Energy systems for growing and fattening cattle A number of countries have changed or modernized their energy systems recently. This was possible because the basis for feed evaluation for lactating cows became more reliable owing to the increased amount of data collected with dairy cattle. However, the basis is much weaker for growing and fattening ruminants, since, for cattle especially, sufficient data on body composition are lacking and the available information shows a large variability. Improvement of this database is needed before a better feed evaluation system can be developed. New methods with modern equipment to quantify the body composition of live animals, and to measure the composition of liveweight gain with regard to fat, protein, etc. during growth, are urgently needed to improve feed evaluation for growing and fattening animals.

Feeding high-yielding ruminants Although nutrient requirements are defined as average figures, it is necessary to increase our knowledge of the variation in requirement for various levels of animal production under various dietary and environmental conditions. Also a better quantification of the effect of factors involved and their interactions is required. Sufficient accurate, well-proven information is lacking in particular from high-yielding animals, where measurement of the required data will easily disturb the animal and decrease its production. Some countries have already introduced a modern protein-evaluation system based on recent knowledge and ideas; other countries are still hesitating. Improvement of the systems is still hampered by the lack of sufficient quantitative information to construct applicable equations, which describe accurately enough processes such as the degradation of protein in the forestomachs, microbial protein synthesis and the digestion and absorption of amino acids from undegraded feed protein and microbial protein under various conditions. Such information will enhance the introduction and updating of protein evaluation systems. So far the prediction of animal production is based on the energy and protein

245 supply from the diet. For a more accurate prediction and a better understanding of feed conversion under more extreme conditions, this may be insufficient. Therefore future research has to provide more quantitative information on the absorbed nutrients and macro molecules, which become available at the organ and tissue level of the animal. Highly sophisticated techniques are required to study these processes in high-yielding ruminants. Interacting factors from the diet, animal and environment involved in the regulation of animal production processes also need to be quantified. Progress in science and technology may lead to processing of feedstuffs or the use of additives in order to optimize the ration to improve the conversion of feed into animal products. Examples are the protection of easily-degradable protein or of fats and the reduction of the effects of anti-nutritional factors. Measuring techniques to study digestive processes in the live animal do not show much improvement apart from the in situ digestion studies with feedstuffs in nylon bags introduced into the digestive tract of fistulated animals. Also re-entrant cannulae need to be replaced by T-shape cannulae in highyielding cattle, if the level of production is to be maintained and flow of digesta not reduced. Studies of net absorption of nutrients from portal-drained viscera may extend our knowledge at that level ( H u n t i n g t o n et al., 1986). However, the number of such experiments has to be reduced as much as possible owing to legislation and the actions of animal welfare groups. The so-called in situ techniques, which look promising to enlarge our knowledge of digestion of individual feedstuffs and the variation in nutrient availability for microbes and host animal, may help to reduce the total number of digestion studies with cattle and sheep. The in situ technique is widely used, especially for information on protein quality and degradability.

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Alderman, G., Griffiths, J.R., Morgan, D.E., Edwards, R.A., Raven, A.M., Holmes, W. and Lessells, W.J., 1974. Application of a metabolisable energy system. H. Swan and D. Lewis {Editors), Nut. Conf. Feed Manuf., Butterworths, London, 7: 37-78. Andersen, H.R., 1975. The Influence of Slaughter Weights and Feeding Levelon the Growth, Feed Conversion, Carcass and Conformation of Bulls. Report No. 430, National Institute of Animal Science, Copenhagen, 124 pp. Andersen, P.E. and Just, A., 1975. Tabellen over fodermidlerssammensaetning m.m. 6 udg. KvaegSvin, Det. kgl. danske Landhusholdningsselskab. Copenhagen, 40 pp. Andersen, P.E. and Just, A., 1983.Tabeller over foderstofferssammensaetning m.m.8, udg. KvaegSvin, Det. kgl. danske Landhusholdningsselskab. Copenhagen, 102 pp. A.R.C., 1965. Requirements for energy. In: The Nutrient Requirements of Farm Livestock, No. 2, Ruminants. Agricultural Research Council, London, Section 6, 193-247. A.R.C., 1980. The Nutrient Requirements of Ruminant Livestock. Technical Review by an Ag-

246 ricultural Research Working Party, Commonwealth Agricultural Bureau, Farnham Royal, 351 pp. Armstrong, D.G., 1964. Evaluation of artificially dried grass as a source of energy for sheep. J. Agric. Sci., 62: 399-417. Autorenkollektiv, 1977. Das D.D.R.-Futterbewertungssystem. V.E.B. Deutscher Landwirtschaftsverlag, Berlin, 256 pp. Beyer, M., Chudy, A., Hoffmann, L., Jentsch, W., Laube, W., Nehring, K. and Schiemann, R., 1986. Das D.D.R.-Futterbewertungssystem. 5th Auflage. V.E.B. Deutscher Landwirtschaftsverlag, Berlin, 328 pp. Bickel, H. and Landis, J., 1978. Feed Evaluation for Ruminants. II. Proposed application of the new system of energy evaluation in Switzerland. Livest. Prod. Sci., 5: 367-372. Blaxter, K.L., 1962. Progress in assessing the energy value of feedingstuffs for ruminants. J.R. Agric. Soc., 123: 7. Blaxter, K.L. and Clapperton, J.L., 1965. Prediction of the amount of methane produced by ruminants. Brit. J. Nut., 19: 511-522. Burlacu, G., 1983. Valorea nutritiva a nutreturilor, normele de hrana si intocmirea ratiilor, Editura Ceres, Bucharest, Vol. 1,382 pp. Buysse, F.X., 1974. Nieuwere inzichten omtrent de energetische voederevaluatie en daarmee aansluitende voedernormen. Deel 5. Meded., RVV No. 304, 28 pp. C.E.C., 1980. Commission of the European Communities. In: C. B~ranger (Editor), Energy and Protein Feeding Standards Applied to the Rearing and Finishing of Beef Cattle. Ann. de Zootech., 29 no. h.s.: 424 pp. C.V.B., 1977a. Veevoedertable, Publ. Centraal Veevoederbureau in in Nederland, Lelystad, 86 pp. C.V.B., 1977b. Manual for the Calculation of the Nutritive Value of Roughages, Publ. Centraal Veevoederbureau in Nederland, Lelystad, 197 pp. C.V.B., 1983. Verkorte Tabel, Voedernormen and voederwaarden, 36 pp. D.L.G., 1982. DLG-Futterwerttabellen ftir Wiederk~iuer 5., Erweiterte und neu gestaltete Auflage. DLG-Verlag, Frankfurt am Main, 120 pp. De Brabander, D.L., Ghekiere, P.M., Aerts, J.V., Buysse, F.X. and Moermans, R.J., 1982. Tests of six energy evaluation systems for dairy cows. Livest. Prod. Sci., 9: 457-469. Energie- und Niihrstoffbedarflandwirtsch. Nutztiere, Nr. 3, 1986. Milchkiihe und Aufzuchtrinder. DLG-Verlag, Frankfurt am Main, 92 pp. Eriksson, S., Sanne, S. and Thomke, S., 1976. Fodermedels tabeller och utfodringsrecommendationer LTs fdrlag, Centraltryckeriet AB, Boras, 62 pp. Frederiksen, J.H., 1984. Planning and Control of Sheep Production. Report No. 575, National Institute of Animal Science, Copenhagen, 133 pp. FutterwerttabeUe fiir Wiederk~iuer, 1982. DLG-Verlag, Frankfurt am Main, 120 pp. Griffiths, W., 1980. Irish Republic energy and protein feeding standards for growing and fattening cattle. Ann. Zootech., 29 no. h.s.: 399-402. Handbuch der Tierern~ihrung, 1972. Publ. Parey, Hamburg, Vol. 1,705 pp., Vol. 2, 752 pp. Harkins, J., Edwards, R.A. and McDonald, P., 1974. A new net energy system for ruminants. Anim. Prod., 19: 141-148. Henneberg, W. and Stohmann, F., 1860. Beitrage zur Berundung einer Rationeler Futterung der Wiederkauer. Schwetsche, Vol. 1 and Vol. 2, 1864. Huntington, G.B., Varga, G.A., Reynolds, P.J. and Tyrrell, H.F., 1986. Net absorption of nutrients and oxygen consumption by portal-drained viscera in relation to energy metabolism by Holstein Cattle. P.W. Moe, H.F. TyreU and P.J. Reynolds (Editors), Proc. 10th Symp. on Energy Metabolism of Farm Animals, Airlie, VA, E.A,A.P.-Publ. No. 32, U.S.A., pp. 22-25. I.N.R.A., 1978. Alimentation des Ruminants. Publ. I.N.R.A., Versailles, 597 pp.

247 I.N.R.A., 1987. Alimentation des Ruminants: R~visions des syst~mes et des tables de I'INRA. Bull. Technique No. 70 C.R.Z.V., de Theix, 222 pp. Johnson, S. and Ohlmer, B., 1972. Feeding Levels, Slaughter Weights and Feed Conversion Ratio in Beef Cattle Production. Lantbrukshogskolans meddelanden, Ser. A, No. 180. Kalashnikov, A.P. and Kleimenov, N.I. (Editors) (1985). Standards and Rations for Feeding Domestic Animals, Agropromizdat, Moscow, Kellner, O., 1905. Die Ern~ihrung der landwirtschaftlichen Nutztiere. Verlagsbuchhandlung. Paul Parey, Berlin, 594 pp. Kellner, 0. and M. Becker, 1966. Grundztige der Fiitterungslehre. Publ. Parey, Hamburg, 374 pp. Lindell, L. and Knutsson, P.G., 1976. Rapeseed meal in rations for dairy cows. Swed. J. Agric. Res., 6, 5-63. Lindhe, B. and Henningson, T., 1967. Cross breeding for beef with Swedish red and white cattle. Landbr. Hogsk. Annlr., 34: 517-550. Lofgren, G.P. and Garrett, W.N., 1968. Net energy tables for use in feeding beef cattle. University of Califnornia, Davis, CA, 25 pp. M.A.F.F., 1975. Ministry of Agriculture, Fisheries and Food. Energy Allowances and Feeding Systems for Ruminants. Tech. Bull. No. 33, H.M.S.O., London, 79 pp. M.A.F.F./A.D.A.S., 1984. Reference book 433. Energy Allowances and Feeding Systems for Ruminants. H.M.S.O., London, 85 pp. McHardy, F.V., 1966. Simplified ration formulation. 9th Int. Congr. Anita. Prod., Edinburgh, Scientific programme and abstracts, Oliver and Boyd, Edinburgh, p. 25 (abstract). Menke, K.H., Raab, L., Salewski, A., Steingass, H., Fritz, D. and Schneider, W., 1979. The estimation of the digestibility and metabolizable energy content of ruminant feedingstuffs from the gas production when they are incubated with rumen liquor in vitro. J. Agric. Sci. Camb., 93: 217-222. Moe, P.W., Flatt, W.P. and Tyrell, H.F., 1972. Net energy value of feeds for dairy cattle. J. Dairy Sci., 55: 945-958. MSller, P.D., Andersen, P.E., Hvelplund, T., Madsen, J. and Thomson, K.V., 1983. A New Method of Calculating the Energetic Value of Feedstuffs for Ruminants. Report No. 555, National Institute of Animal Science, Copenhagen, 60 pp. Nehring, K. and Friedel, K., 1985a. Gedanken zur Sch~itzung des energetischen Futterwertes. 1. Mitt.: Sch~itzungdes energetischen Futterwertes for Rinder. Arch. Tierernaehr., 35: 295-319. Nehring, K. and Friedel, K., 1985b. Gedanken ziir Sch~itzung des energetischen Futterwertes. 2. Mitt.: Erweiterte Betrachtungen zur Sch~itzung des energetischen Futterwertes des Rindes. Wissensch. Zeitschr. der Wilhelm-Pieck-Universita't, Rostock, 34: 24-35. Neimann-Sorensen, A., 1980. Survey of the energy feeding standards used in the C.O.S.T. countries and of the experimental background. Ann. Zootech., 29 no. h.s.: 17-26. Nordisk Jordbrugsforskning, 1969. Fodermiddeltabel 51.1 Publ. Mariendals Boktrykkeri A/S, Gjovik, 62 pp. Norrman, E., 1977. Notkott, production och ekonomi. Helmenius ed. L T, Stockholm. N.R.C., 1978. Nutrient Requirements of Dairy Cattle, 5th revised edn. Publ. N.R.C., National Academy Press, Washington DC, 76 pp. N.R.C., 1984. Nutrient Requirements of Beef Cattle, 6th revised edn. Publ. N.R.C., National Academy Press, Washington DC, 90 pp. Obracevic, C., 1984. New Systems of Feed Evaluation. Feed Manufacturers Association, Zagreb, 60 pp. Schiemann, R., Nehring, K., Hoffmann, L., Jentsch, W. and Chudy, A., 1971. Energetische Futterbewertung und Energienormen. VEB/DLV Berlin, 344 pp. Schneeberger, H. and Landis, J. (Editors), 1984. Ftitterungsnormen und Niihrwerttabellen ftir Wiederk~iuer, 2rid ed., Landwirtschaftliche Lehrmittelzentrale (LMZ), CH-3052 Zollikofen, Switzerland, 119 pp. Thorbeck, G. and Henckel, S., 1976. Energetisk vedlige holdelsesbehov hos calve. Report No. 125, National Institute of Animal Science, 4 pp.

248 Tilley, J.M.A. and Terry, R., 1963. J. Brit. Grassl. Soc., 18: 104-111. Van Es, A.J.H., 1975. Feed evaluation for dairy cows. Livest. Prod. Sci., 2: 95-107. Van Es, A.J.H., 1978. Feed evaluation for ruminants. I. The systems in use from May 1977 onwards in The Netherlands. Livest. Prod. Sci., 5, 331-345. Van Es, A.J.H., 1986. Energy values of feeds for livestock and their prediction. Neth. J. Agric. Sci., 34" 405-412. Van der Honing, Y. and Steg, A., 1984. Relationship between energy values of feedstuffs predicted with thirteen feed evaluation systems for dairy cows. I.V.V.O. Report No. 160, 66 pp. Van der Honing, Y., Steg, A. and Van Es, A.J.H., 1977. Feed evaluation for dairy cows: tests on the system proposed in The Netherlands. Livest. Prod. Sci., 4: 57-67. Van der Meer, J.M., 1984. C,E.C. Workshop on Methodology of Feedingstuffs for Ruminants. European "In Vitro" Ringtest 1983-Statistical Report. I.V.V.O. Report No. 155, 42 pp. Van Soest, P.J., Fadel, J. and Sniffen, C.J., 1979. Discount factors for energy and protein in ruminant feeds. In: Proc. Cornell Nutrition Conference for Feed Manufacturers, Ithaca, NY, pp. 63-75. Vermorel, M., 1978. Feed evaluation for ruminants. II. The new energy systems proposed in France. Livest. Prod. Sci., 5: 347-365.

Protein Anschuss ffirBedarfsnormen, 1986.Energie und N~ihrstoffbedarfLandwirtschaftlicherNutztiere, No. 3. Milchkiihe und Aufzuchtrinder,DLG-Verlag, Frankfurt am Main, 92 pp. A.R.C., 1980. The Nutrient Requirements of Ruminant Livestock.Technical Review by an AgriculturalResearch Council Working Party, Commonwealth AgriculturalBureau, Farnham Royal, U.K., 351 pp. A.R.C., 1984. The Nutrient Requirements of Ruminant Livestock. Suppl. No. 1. Report of the Protein Group of the A.R.C. Working Party. Commonwealth AgriculturalBureau, Farnham Royal, U.K., 45 pp. Burroughs, W., Nelson, D.K. and Mertens, D.R., 1975. Evaluation of protein nutritionby metabolisableprotein and urea fermentation potential.J. Dairy Sci.,58, 611-619. Crooker, B.A., Sniffen,J., Hoover, W.H. and Johnson, L.L., 1978. Solvents for solublenitrogen measurements in feedstuffs. J. Dairy Sci., 61,437-447. Henderickx, H. and Martin, J., 1963. In vitro study of the nitrogen metabolism in the rumen. C.R. Rech. Inst. Rech. Sci. Ind. Agric., 31: 7-14. I.N.R.A., 1978. Alimentation des Ruminants. I.N.R.A. Publications, Versailles, 597 pp. Kristensen, E.S., Moller, P.D. and Hvelplund, T., 1982. Estimation of the effective degradability in the rumen using the nylon bag technique combined with outflow rate. Acta Agric. Scand., 32: 123-127. Landis, J., 1979. Die Protein und Energieversorgung der Milchkuh. Schweiz. Landwirtsch. Monatsch., 57: 381-390. Landis, J., 1984. Bewertung des Proteins in Wiederkiiuerfutter. In: Schneeberger, H. and Landis, J. (Editors), Ffitterungsnormen und Nii_hrwerttabellen Rir Wiederkiiuer. LMZ, Zollikofen (CH), pp. i4-18. Madsen, J. and Hvelplund, T., 1985. Protein degradation in the rumen. A comparison between in vivo and in vitro and buffer measurements. In: Protein Evaluation for Ruminants. Acta Agric. Scand., Supp. 25, pp. 103-124. Mahdevan, S., Erfle, J.D. and Sauer, F.D., 1980. Degradation of soluble and insoluble proteins by Bacteroides amylophilus protease and by rumen microorganisms. J. Anita. Sci., 50: 723-728. N.K.J./N.J.F., 1985. Protein Evaluation for Ruminants. Acta Agric. Scand., Suppl. 25, 220 pp.

249 N.R.C., 1985. Ruminant Nitrogen Usage. U.S. National Academy of Science, Washington, DC, 138 pp. Orskov, E.R. and Mehrez, A.Z., 1977. Estimation of extent of protein degradation from basal feeds in the rumen of sheep. Proc. Nutr. Soc., Vol. 36, 78A. Orskov, E.R. and MacDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. J. Agric. Sci., 92: 499-503. Rohr, K., Lebzien, P., Schafft, H. and Schulz, E., 1986. Prediction of duodenal flow of non-ammonia nitrogen and amino acid nitrogen in dairy cows. Livest. Prod. Sci., 14: 29-40. Roy, J.H.B., Balch, C.C., Miller, E.L., Orskov, E.R. and Smith, R.H., 1977. In: S. Tamminga (Editor), Protein Metabolism and Nutrition. E.A.A.P. Publ. No. 22, PUDOC, Wageningen, pp. 126-129. Waldo, D.R. and Glenn, B.P., 1982a. Foreign Systems for Meeting the Protein Requirements of Ruminants. In: F.N. Owens (Editor), Protein Requirements for Cattle, Oklahoma State University, Stillwater, OK, pp. 296-309. Waldo, D.R. and Glenn, B.P., 1982b. Comparison of New Protein Systems for Lactating Dairy Cows. J. Dairy Sci., 1115-1133.

Appendix: Energy Systems for Ruminants Note: Countries in the E.A.A.P. which have adopted one or more systems from other countries that have been described below are not mentioned in this appendix. The systems mentioned relate to cattle unless otherwise stated.

(1) Starch equivalent, SE~o according to the KeUner procedure, as used in Germany (F.R.G. ) and Austria One unit SEK is equivalent to 2.36 kcal or 9.88 kJ net energy; the original starch equivalent is defined as the "fattening potential" of 1 g digestible starch, which equals 2.36 kcal or 9.88 kJ.

Nutritive value Roughages. SEK= 0.94 D X P + 1.91 D X L + D X F + D X X - X F *x (units kg-1; D X P etc. as g kg -~ ) The value of x depends upon type and crude-fibre content of the product. Concentrates. SEK= (0.94 D X P + f , D X L + D X F ÷ D X X ) (units k g - 1)

•V

Remarks. The value o f f depends upon the type of product; varying 1.91-2.41. The value of V (value number according to Kellner) depends upon the type of product and varies between 0.7 and 1.0.

250

Requirements Growth and fattening cattle ( D.L.G., 1982). Total requirement, as starch equivalent (SEK) , dependent on W and liveweight gain is presented in Table V of D.L.G. (1982). See also Table IV in this chapter.

Sheep. (D.L.G., 1982). (Abstract from Table VI in D.L.G., 1982). Maintenance at W = 60 kg: 480 SEK. Pregnancy including maintenance at W = 60 kg: < 105 days pregnancy; 550 SEK; > 105 days pregnancy; 800 SE K. Lactation including maintenance at W -- 60 kg: single lamb (gain 300 g), 1140 SEK; twin lambs (gain 200 g), 1570 SEK'I-additional feed. Growth and fattening requirements (SEK) are shown below Daily gain (g day - 1)

Lambs (male) Lambs (female)

W=20 kg W=40 kg W=20 kg W=40 kg

100

200

300

400

375 620

480 755 510 840

595 930 650 1060

720 1120 -

References C.E.C., 1980. Futterwerttabelle flit Wiederkiiuer, 1982. Kellner, 0., and Becker, M., 1966.

(2) Dutch starch equivalent, S E ( N L ) , system used for beef cattle in Belgium SE ( N L ) unit based on the net energy for fattening similar to starch equivalent SEK, b u t with major modifications to equations. 1 unit SE ( N L ) is equivalent to 2.36 kcal or 9.88 kJ.

Nutritive value Roughages. The same equation as for SEE or the shorter equation (when all digestible nutrients are not available ) as follows:

SE ( NL ) = DOM-O.06 D X P - X F . x ( units k g - 1, DOM, D X P etc. as g k g - 1) The value of x depends upon type and crude-fibre content of the product.

251 Concentrates. SE ( N L ) = (0.94 D T P + 3 D X L + D X F + D X X - 0 . 2 4 sugars) • V (units k g - 1 ) Remarks. D T P is generally calculated as D T P = D X P - ( X P - T P ) . Correction for sugars only if sugar content exceeds 80 g k g - 1 ( dry or air-dry matter). The value of V (value number according to Kellner) depends upon the type of product and varies between 0.7 and 1.0. Note: classification of feedstuffs in roughages and concentrates is not always clear. Requirements Milk production. Maintenance: ( 3.33 W + 1000) SE {NL). For each kg fat-corrected milk ( 4% fat): 286 SE (NL). Beef production. Tables with a S E ( N L ) requirement for 1000-g daily gain at different age and liveweight are presented. See Table IV. Maintenance ( kg SE (NL)): 0.8 + 0.0045 W (Alderman et al., 1974 ). Growth ( kg SE ( NL )) per kg gain: 1.22 + 0.00273 W ( Buysse, 1974 ). References Aldermanet ai., 1974. Buysse, F.X., 1974. Verkorte Tabel: Voedernormenen voederwaarde,1975. (3) Scandinavian feed unit, SFU(DK), system used in Denmark Essentially a modification of the Kellner starch equivalent system. Scandinavian feed unit, SFU (DK) based on the net energy of 1 kg of barley at 85% dry matter. 1 unit SFU (DK) is equivalent to 1650 kcal or 6.91 MJ net energy. Nutritive value Fresh forage, hay and straw. S F U ( D K ) = (1.43 D X P + 1 . 9 1 D X L + D X F + D X X - 0 . 6 4 ( feed units k g - 1, D X P etc as g k g - 1)

X F ) ,1.333/1000

Ensiled forage. S F U ( DK) = (1.43 D X P + D X L + D X F + D X X ) . l . 3 3 3 . 0 . 8 / l O00 Concentrates. S F U ( D K ) = (1.43 D X P + f , D X L + D X F + D X X ) , 1.333, V/1000

252

Remarks. The value o f f depends on the type of products, varying from 1.91 to 2.41. The value of V depends on the type of product, varying from 0.7 to 1.0. A new method has been proposed by M611er et al. (1983) to calculate the net energy from an equation with digestible energy and crude fibre as dependent variables.

Requirements Milk production. Maintenance: ( ( 0.0033 W + 1 ) • 1.333 ) S F U ( D K ) . For each kg fat-corrected milk (4% fat ) : 0.40 S F U ( D K ) .

Growth and fattening. Bulls: ADG = 2 0 6 . 5 - 4 . 2 7 W + 0 . 0 0 2 W 2 + 5 7 4 . 7 E - 3 6 . 9 E 2 + 0 . 0 3 8 ( W , E ) Heifers: ADG =550.8 - 3.83 W+O.OO6W2+312.5E-lO.3 E 2 - 0 . 2 7 ( W . E ) where ADG = daily gain in g and E = S F U ( D K ) day - 1.

Sheep. SFU(DK) kg at W

Maintenance and pregnancy: Lactation: Days 1-60 Single lamb Twin lambs Days 61-120 Single lamb Twin lambs

60 kg

80 kg

100 kg

0.70

0.85

0.95

1.50 1.90 1.30 1.70

1.65 2.00 1.45 1.80

1.75 2.15 1.55 1.95

References Andersen, H.R., 1975. Andersen and Just, 1975. Andersen and Just, 1983. C.E.C., 1980. Fodermiddeltabel, 1969. Frederiksen, J.H., 1984. Handbuch der Tierernaehrung, 1972, Vol. 2. Page 341. MSller et al., 1983.

(4) Fattening feed unit, FFU, system used in Norway and Finland F F U fattening feed unit based on the net energy for fattening of 1 kg of barley ( 85% dry matter) primarily based on Kellner's system. 1 F F U is equivalent to 6910 kJ net energy.

253

Nutritive value Roughages. F F U = ( 9 . 3 8 D X P + 1 8 . 8 4 D X L + 9 . 8 8 D X F + 9 . 8 8 D X X - X F ,3x)/6910

(units kg -1, DXP etc. as g kg -1) Concentrates. F F U = ( 9.38 D X P + f , D X L + 9.88 D X F + 9.88 D X X ) • V/6910 Remarks. The factors below have to be included in the equations.

Feeds of animal origin Cereals, other concentrates Wheat bran, etc. Silages Hay Straw

Fat factor / ( k J g -1)

Value number (Y)

23.85 20.92 20.92 9.87 18.84 18.84

1.00 0.95 0.90 0.80

Crude-fibre deduction x ( k J g -1)

- 4.2 -6.3 - 5.7

Requirements Milk production. Finland and Norway: maintenance (W°7~/500 °'75) • 4.0 FFU.

For each kg fat-corrected milk (4% fat): 0.40 FFU. Liveweight change _+ 2.5-3.0 FFU per kg change. Growth and fattening. (1) Finland, separate tables of FFU requirement for bulls and heifers are in use in Finland (C.E.C., 1980). See also Table IV in this chapter. (2) Norway, separate tables for growing steers and heifers, examples: steer 300 kg, gain 0.5-0.8 kg day -I 4.0-5.0 FFU day-I; heifer 300 kg, gain 0.5-0.7 kg day- 1 4.0-4.5 F F U / d a y - 1. Sheep. Data are shown below.

(1) Finland 60-kg liveweight ewe Maintenance requirement Pregnancy requirement

Lactation requirement

FFU day- 1 indoors grazing Months 1-3 Month 4 Month 5 I lamb 2 lambs 3 lambs

0.6 0.8 0.6 0.9 1.1 1.1 1.5 1.8

254 (2) Norway 60-kg liveweightewe

FFU day- 1

Maintenance, including wool growth Production feed, last 6 months of pregnancy: ewes in good condition ewes in poor condition Production feed, milk production (3-4 weeks) 1 lamb 2 lambs

0.57-0.69 0.1-0.2 0.3-0.4 1.1 1.7

Growing lambs, including maintenance in FFU day- 1 Liveweight (kg)

Females Males/finishing

30-35

35-40

40-45

45-50

50-55

55-60

0.62 0.88

0.65 0.91

0.69 0.95

0.72 0.98

0.75 1.02

0.78 1.05

Goats. Data are shown below (1)

F in lan d

Maintenance Pregnancy Lactation Growing kids

0.01 W + 0 . 1 F F U day -~ Month: 4 + 0.2 F F U d a y Month: 5 + 0.5 F F U d a y 0.37 F F U kg -~ 3.5% fat milk 0.30 F F U d a y - 1 up to 1.5 m o n t h s 0.40 F F U day-~ 1.5-3 m o n t h s 0.55 F F U day-1 3-4.5 m o n t h s

(2) No r way Maintenance

FFU day- 1

Live weight (kg) 30

40

50

60

70

0.41

0.51

0.60

0.69

0.77

P r o d u c t i o n feed, pregnancy, "change over" and growth M a t u r e goats 8-3 weeks before kidding 0.2 F F U day - 1 M a t u r e goats last 3 weeks before kidding 0.5 F F U d a y - 1

255

0.4 FFU day-1 3.0 FFU day- 1 0.1 FFU day-

Pregnant young goats Per kg liveweight gain Lactating young goats ( for growth) Production feed, milk production Fat content of milk ( % ) 3.0 FFU kg-1 milk 0.34

3.5 0.37

Growing kids, maintenance plus growth Age in weeks 0-6 6-12 12-18 Liveweight (kg) 3-8 8-12 12-17 FFU day -1 0.30 0.40 0.55

4.0 0.40

18-34 17-27 0.75

34-44 27-35 0.85

44-kidding 35-45 0.90

References C.E.C., 1980. Eriksson, Sanne and Thomke, 1976. Fodermiddeltabel, 1969. Handbuch der Tierernaehrung, 1972. Vo. 2. p. 341. Touri, M., personal communication, 1986. Sundstol, F., personal communication, 1986.

(5) Rostock system, EFr, developed and used in the G.D.R. EFr is a feed unit based on the net energy for fattening (NEFr) of I kg of barley as fed. Nutritive value EFr (kcal) = 0.68 D X P + 3.01 D X L + 0.80 ( D X F + D X X ) , which is based on: NEFr = 1.71 D X P + 7.52 D X L + 2.01 ( D X F + D X X ) and EFr (feed u n i t s ) = N E F r (kcal)/2.5 For the calculation of the nutritive value of rations, sometimes an additional correction is needed, depending upon dE of the ration. Instead of this correction of the nutritive value of rations, Nehring and Friedel (1985a, b) proposed the calculation of NEFr and EFr from DOM and indigestible organic matter (IDOM), supposing additivity of the feedstuffs in the ration. Requirements Milk production. Maintenance: 26 W °75 EFr. For each kg fat-corrected milk (4% fat): 285 EFt. Growth and fattening. Maintenance: 24.8 W°75EFr. Daily gain of 1000 g (including maintenance) :

256

(1204 + 24.849 W - 0.0097962 W 2)/2.5 ) EFr

Sheep. Maintenance: 41.4 kcal NEFr k g - l W °'75. Pregnancy: 64.4+5.413 t + 0.0555426t 2 kcal NEFr d a y - 1 ( t-- number of days pregnant). Lactation: 940 kcal NEFr kg-1 milk. Growth and fattening of growing lambs: 100 g daily gain: 372 + 23.788 W - 0.074048 W 2 200 g daily gain: 416 + 33.967 W - 0 . 1 0 6 1 9 0 W 2 300 g daily gain: 461 + 44.145 W - 0 . 1 3 8 3 3 3 W 2 Mature sheep: 6 Mcal NEFr kg-~ liveweight gain Practical allowances are + 10% for cattle and + 25% for sheep above requirements stated here, see Schiemann et al., 1971.

References Autoren Kollektiv, 1977. Beyer, M. et al., 1986. Nehring, K. and Friedel, K., 1985a. Nehring, K. and Friedel, K., 1985b. Schiemann et al., 1971.

(6) Scandinavian metabolizable energy, ME(S), system developed from A.R.C. (1965) and used in Sweden Sweden used the Scandinavian fodder unit, SFU, but adopted a simplified version of A.R.C. (1965) for dairy and beef cattle in the early 1970s. After the publication of the M.A.F.F. (1975) standards, these were mainly adopted but with modifications based on feeding trials (Norrman, 1977). Maintenance requirements were based on the work of Thorbek and Henckel (1976). Metabolizable energy ( ME ), Mcal k g - 1 DM, taken from tables, or predicted from in vitro digestibility measurements of forages.

Nutritive value See Table V.

Requirements Milk production. Maintenance: 0.121 W °'75 Mcal ME ( S ). For each kg fat-corrected milk (4% fat): 1.2 Mcal ME (S). Plane of nutrition effect: none. Efficiencies of ME utilization: as U.K. (M.A.F.F., 1975 ).

Growth and fattening. Standards are mainly based on the British recommen-

257 dations as they appear in Technical Bulletin 33 ( M.A.F.F., 1975 ), modified in the light of feeding trials (Normann, 1977). Maintenance-energy requirements are as Thorbeck and Henckel (1976). See Table IV. Testing of system: Requirements for beef cattle derived from feeding trials, rather than factorial approach (Johnsson and Ohlmer, 1972; Lindhe and Kenningson, 1967).

References C.E.C., 1980. Eriksson, Sanne and Thomke, 1976. Fodermiddeltabel,1969. Lindell L. and Knutsson, P.G., 1976. Normann, E., 1977. Thorbek, G. and Henckel,S., 1976.

(7) British metabolizable energy, ME ( GB ), system used in the U.K. An ME system was introduced in 1976, based on the A.R.C. (1965) proposals simplified and adjusted to fit the results of feeding trials. This replaced the U.K. version of SEK,expressed as pounds of SEK. Metabolizable energy ( ME ), MJ kg-1DM, measured at maintenance with sheep.

Nutritive value Calculation of ME value: (1) from Weende digestibility data using an equation published by Schiemann et al. (1971) (see Table V); (2) from digestible organic-matter data, assuming organic matter has an energy value of 19 MJ k g - 1, and that M E / D E = 0.81; (3) direct measurements with sheep at maintenance; (4) prediction from chemical and in vitro analysis, used particularly on forages of variable ME value. Efficiencies of ME utilization: maintenance, km= 0.72; lactation, k~= 0.62; growth, kg= 0.0435. ME/DM.

Requirements Milk production. Maintenance: (8.3 + 0.091 W) MJ ME (GB). For each kg fat-corrected milk (4% fat): 5.3 MJ M E ( G B ) . Plane of nutrition effects: no allowance made. Energy value of liveweight change in cows = 20 MJ k g - 1. Efficiency of utilization of mobilized body energy for milk = 0.82. Efficiency of ME utilization for gain for lactating cow = 0.62.

Growth and fattening. These are expressed as MJ of NEmg, to facilitate ration formulation. Feed ME values are converted to appropriate NEm~ values by the use of the Animal Production Level (APL) defined as:

258

A P L = 1 -~

LWG(6.28+O.0188 W) ( 1 - 0 . 3 LWG) (5.67 + 0.061 W)

Net energy of feed or ration,

NEmg ( MJ k g - 1 DM ) =

(ME/DM) 2×APL 1.39 M E / D M + 23 ( A P L - 1 )

Maintenance, Em = 5.67 + 0.061 W MJ of NEmg Production,

Ep =

LWG(6.28+O.188 W) (1-0.30LWG)

MJ of NEmg

Testing of system: the simplified system was developed using a database of suitable feeding trials with dairy cows and beef cattle (Alderman et al., 1974). No database for sheep was used.

Sheep. Maintenance: indoors 1.2+0.13 W MJ day-l; outdoors 1.4+0.15 W MJ day- 1. For liveweight gain: liveweight gain energy value, EVe: logloEVg= 1.11 logloLWG+0.004 W+0.88 MJ kg -1 where LWG is in g day -1. ME for gain: EVg/kg.

References Aldermanet al., 1974. M.A.F.F., 1975. M.A.F.F., 1984.

Requirements according to The Nutrient Requirements of Ruminant Livestock, A.R.C. (1980). Maintenance and milk production. Requirement for maintenance = Z /km where fasting metabolism, Z = ( 0.53 ( W/1.08 ) o.67+ 0.0043 W) and km -- 0.35q + 0.503. For milk production, Z is calculated as above. Energy retention in M kg milk (R):

R = M . (1.509+0.0406 F) where F= g fat kg -1 . kl = 0.35q- 0.420 Level of feeding FL = 1 + ( R/kl ) / ( Z/km) Correction for level of feeding: 1 + 0.018 ( F L - 1 ) Total requirement= (1 + 0.018 ( F L - 1 ) ) (R/kl + Z/km)

Growth and fattening. Maintenance requirements for castrates and heifers as above, 15% more for bulls. Energy value of liveweight gain, EVg, as MJ k g - 1 given by:

259

EV~= (4.1 +0.0332 W - 0.000009 W2)/(1-0.1475 LWG) where LWG is liveweight gain as kg day-1. Estimate is to be reduced by 15% for bulls and for large breeds, or increased by 15% for heifers and for small breeds. Energy retention (ER) = EVJk~, where kf= 0.78 q + 0.006 at a plane of nutrition of 2 × maintenance.

Sheep. Maintenance: Z/km MJ ME day-1 where Z= 0.251 (W/1.08) o.7~ Growth and fattening: EVJkg MJ ME d a y where EV~=2.5+0.35 Wfor males: 4.4+0.32 Wfor castrates; 2.1+0.45 Wfor females. Pregnancy: maintenance: Z = 0.226 ( W/1.08 ) 0.75 Daily energy retention, R: log~oR = 3.322 - 4.979 exp ( - 0.00643 t) where t is number of days pregnant. Lactation: maintenance: Z = 0.226 (W/108) o.v5+ 0.0106 W For each kg of milk: ME--EVJkl resulting in 7.5 MJ ME E Vg= 4.5 + 0.0025d MJ kg-~ where d is days of lactation and a fat content of 70 g kg-~ is assumed. Level of feeding correction factor: 1 + 0.018 ( F L - 1 )

Reference A.R.C., 1980.

(8) Net energy lactating cows, NEL(US), U.S. N.R.C., 1978 (used in Israel) Net energy lactation, NEL (US), expressed as Mcal kg- 1DM, calculated from TDN, DE or ME values

Nutritive value NEL(US) (in Mcal) = 0.703 M E - 0 . 1 9 NEL(US) (in Mcal) = 0.710 D E - 0 . 5 1 NEL(US) (in Mcal) = 0.0245 TDN%-0.12 (assuming 1 kg TDN = 4.409 Mcal DE) Requirements Milk production. Maintenance: 0.08 W °'75 Mcal NEL ( US ): for each kg of fatcorrected milk (4% fat) : 0.74 Mcal NEL ( US ); for each kg liveweight gain, add 5.12 Mcal; for each kg liveweight loss, deduct 4.92 Mcal.

260

Reference N.R.C., Washington,1978. Nutrient Requirementsof Dairy Cattle, 5. (9) Metabolizable energy, ME(IRL), used in Ireland Both the starch equivalent and the Scandinavian feed unit were used in Ireland, but there was no officially-adopted system. The M.A.F.F. (1975) standards were unofficially introduced, but a joint committee proposed minor revisions (Griffiths, 1980).

Nutritive value Metabolizable energy, M E ( I R L ) MJ k g - l D M taken from tables or predicted from in vitro digestibility. Plane of nutrition effects: none. Efficiencies of ME utilization: as U.K. ( M.A.F.F., 1975 ). Testing of system: maintenance requirements were estimated by regression of ME intake on energy and N retention in Friesian cattle. For energy value of body gains, EVg, the data of Lofgren and Garrett (1968) were preferred. Requirements Milk production. As in M.A.F.F. (1975). Growth and fattening. MEmg = MEre + E Vg/kg see Table IV. (10) Feed unit for milk production, VEM, and for growth and fattening, VEVI, used in The Netherlands since 1 May 1977 Feed unit for milk, VEM, expressed as g kg-1 of barley, using net energy for lactation, NE1 as Mcal kg -1 as the reference. Feed unit for fattening, VEVI, expressed as g k g - 1 of barley using net energy for maintenance and gain NEmg as the reference.

Nutritive value GE(kcal kg -1) =5.77XP + 8.74XL + 5.0XF + 4.06XX - 0.15 sugars q = 100 ME/GE ME values of feeds calculated as in Table V. Net energy for lactation, NEI values, kcal kg-1, calculated as: NE1=O.6(l+O.O4(q-57)) .0.9752 M E ( k c a l kg -1) VEM= NE 1/1.65 Net energy for growth and fattening, NEg values (kcal k g - 1), calculated as:

261

0.00493 q-0.584 ) N E e (kcal) = M E (0.0078 q + 0.006 ) / (0.00287 q + 0.554) 1.5 t- 1

VE VI= NEJ1.65 Requirements Milk production. Maintenance: 42.4 W °75 VEM. Milk production: 442 M VEM at plane of nutrition FL = 2.38. M-- kg fat-corrected milk (4% fat). Including effect of plane of nutrition of the total requirement for a cow weighing 600 kg is to be calculated as: V E M = 5013 + 440 M + 0.7293 M 2 Growth and fattening. Maintenance: 78.87 W °'75 as kcal d a y - 1. Growth, as retained energy, REg: ( 500 + 6 W) ADG REg (kcal) = 0.3 ( 1 - A D G ) ADG = average daily gain, kg. For correction to allowances for practice see van Es (1978).

Sheep. (C.V.B., 1983). Maintenance, lactation and pregnancy of ewes (in VEM) : Non-pregnant, non-lactating ewes 7.5W + 170 Ewes pregnant during 0-2.5 month 8.0W + 170 Ewes pregnant (single) during 2.5-4.5 month 10.5W+270 Ewes pregnant (twin) during 2.5-4.5 month 12.5W+250 Lactating ewes

Single lamb: Twin lambs: Triplet lambs:

Month 1

Month 2

Month 3

1920 2460 2660

1780 2190 2340

1520 1720 1860

Growth and fattening: male lambs (20-50 kg) (in VEVI). W °'75 • 65 VE VI maintenance -

1.65

V E V I growth=

( ( 6 0 0 + 6 0 , W) , L W G ) 1-1.2,LWG ,0.985/1.65

262

V E V I = ( V E V I maintenance + V E V I growth) • C where C is a correction factor dependent on LWG (daily gain in kg) : at LWG=0.2, 0.25, 0.30, 0.35 and 0.40; C is respectively 1.04, 1.07, 1.10, 1.12 and 1.14. Goats. ( C.V.B., 1983 ). Maintenance: at W = 60 kg: 800VEM Non-lactating pregnant including maintenance (last months) at W = 65 kg: 1250 VEM Young pregnant goats (age 10 months) at W = 45 kg: 1070 VEM. Young pregnant goats (age 12 months) at W = 55 kg: 1250 VEM. Lactation, including maintenance, W = 60 kg: 747 + 463 • FCM (FCM = fat-corrected milk 4% fat). References Manual for the calculation of the nutritive value of roughages, 1977. Van Es, A.J.H., 1978. Veevoedertabel, 1977. Verkorte tabel. Voedernorraen en voederwaarden, 1977, 1983.

(11) Unitd fourrag~re lait, UFL, and Unitd fourrag~re viande, UFV, used in France since 1978 Feed unit for milk (UFL) expressed as kg kg- 1 of barley, using net energy for lactation, NE1 as Mcal kg-1 as the reference. Feed unit for meat (UFV) expressed as kg kg- ~ of barley, using net energy for maintenance and gain, NEm~ as Mcal kg- 1 as the reference. Nutritive value Gross energy ( GE). (1) Roughages: GE = 4531 + 1.735 X P +p ( values in organic matter ) ( kcal kg- 1 ) p depends upon the type of product. ( 2 ) concentrates: GE=5.72 X P + 9 . 5 XL+4.79 XF+4.17 X X + p (in dry matter) (kcal/kg -1) The value ofp depends upon the type of product (according to Schiemann et al., 1971 ). Digestible energy (DE). DE = G E . DE/GE DE/GE calculated: Roughages: DE/GE = 1.O087DOM/OM- 0.0377. Cereals and cereal by-products: DE/GE = D O M / O M - 0.013.

263 Oil seeds and oil cakes: DE/GE-- D O M / O M - 0.020. Other products: DE/GE = D O M / O M - 0.015. Metabolizable energy values (ME). ME=DE,ME~DE M E / D E calculated: M E / D E = 0.86991 - 0.0000877 X F - 0.000174 X P ( in dry matter). See also Table V. UFL. NE1 values, kcal kg-1, calculated as: N E I = (0.6+0.24(q-0.57)) ME(kcal kg -1) where q = ME/GE UFL ( kg kg- ~) = NEJ1730 Note: for sugarbeets and fodderbeets the above value is multiplied by 0.9. UFV. APL = 1.5: Net energy of barley: 1855 kcal. UFV= ( M E × king)/1855 ( M E in kcal ) kin • kg • A P L where king- kg + ( A P L - 1) k~ UFV ( kg kg- ~= NEmJ1855 Requirements Milk production. Maintenance: (1.4 + 0.006 • W ) UFL For each kg fat-corrected milk (4% fat): 0.43 UFL. For each kg liveweight gain, add 3.5 UFL. On a ration basis additional corrections are needed, dependent upon feeding level and quality of the ration (q value and percentage of concentrates in the ration). Remark: plane of nutrition effect applied at a whole ration. Growth and fattening. NEmg values kcal kg- 1 calculated as: NEmg = kmg, M E ( kcal kg- 1) See Table IV of this chapter. Sheep. Maintenance: 0.033 UFL/kg°75; or 0.397 MJ ME/kg °'7~.

264

Pregnancy UFL day- 1per kg foetus Month 1-3 Month 4 Month 5

0.0017 0.044 0.070

Lactation UFL kg-' milk Month 1 Month 4

0.61 0.68

Growth and fattening: table values only in I.N.R.A. (1978), p. 429. For a liveweight gain of 200 g d a y - 1, U F V d a y - 1 requirements for male lambs of liveweight W are: 15, 0.58; 25, 0.93; 35, 1.27.

Goats. Maintenance: 0.01 W + 0.21 U F L d a y Lactation: 0.41 UFL kg-1milk of 3.5% fat Pregnancy: 0.01 W + 0 . 5 6 U F L day -1 Growing kids: data shown below Age ( months )

UFL day- 1

1 3 5 7

0.44 0.57 0.68 0.71

References I.N.R.A., Alimentation des Ruminants (1978). Vermorel, M. (1978). (12) Net energy for lactation, N E L ( D ) , system used in F.R.G. and Austria since 1982 Net energy for lactation N E L ( D ) as M J k g - ' as fed, calculated from ME as in the Dutch V E M system.

Nutritive value ME calculated from D X P , DXL, D X F and D X X as in Table V. GE ( M J kg -1) = O.0242XP+O.O366XL + 0.0209XF + 0.0170XX - 0.0007 sugars ( g k g - 1) Note: correction for sugars is only applied if product contains more than 80 g k g - 1 DM.

265

q = 100 ME/GE

NEL(D) =ME(O.6+O.OO24(q-57)) MJ kg -1 Requirements Milk production. Maintenance: 0.293 W °75 MJ N E L ( D ) . Milk production: Per kg fat-corrected milk (4% fat) 3.17 MJ N E L ( D ), which figure includes a correction of 0.07 MJ NEL (D) for increased plane of nutrition.

References D.L.G., 1982. Energie- und N~ihrstoffbedarf Landwirtschaftliche Nutztiere, 1986.

(13) Net energy lactation, N E L ( GR ), and modified starch value ,MSV, systems used in Greece Net energy for lactation, (NEL(GR)), as MJ kg -1, calculated from ME. Modified starch value (MSV) as kg kg -1 based on net energy fat (NEFr) of Schiemann et al., 1971.

Nutritive value N E L ( G R ) is calculated from ME values of feeds (see Table V and VI), as defined in the system used in The Netherlands ( see p. 260). MSV is calculated from NEFr: M S V = NEFr/2.60 kg-1. NEFf is calculated as in the Rostock system, see p. 255.

Requirements Milk production. As for N E L (D) of the F.R.G., see p. 264. Maintenance NEL(GR) = 0.293W °'Ts MJ NEL(GR) Per kg FCM milk 3.17 NEL (GR), which includes a plane of nutrition effect.

Growth and fattening. Calculated from NEFr requirements of GDR, converted to MSV for 1 kg daily gain: MSV= (1024 + 24.849 W - 0.0086314 W 2) 1.1/2.4 See Table IV. (14) Netto Energie Milch, NEL(CH), and Netto Energie Mast, NEV(CH), systems used in Switzerland since 1979 Switzerland introduced the NEt and NEg system developed by van Es (1978) in 1979 (Bickel and Landis, 1978) but expressed as M J kg -I not as feed units.

266

Netto Energie Milch (Energie nette lactation), NEL (CH) Netto Energie Mast, (Wachstum) ( Energie nette viande ), NEV ( CH ) both as MJ kg- 1. Conversion factors: N E L ( C H ) = 0.0069 V E M = 6.90 UFL; N E V ( C H ) = 0.0069 V E V I = 7.34 U F V Nutritive value Both values are calculated from ME values as for The Netherlands, using the same formula, but using actual values for GE, not calculated ones, to obtain q, as far as possible. Plane of nutrition effects: as for The Netherlands, but no adjustments for requirements above and below 2.38 times maintenance. Efficiencies of ME utilisation: as for The Netherlands. Testing of system: for dairy cattle, the tests of van der Honing et al. (1977) were relied upon. For beef cattle the standards were derived from Swiss feeding trials. Requirements Milk production. Maintenance: 0.293 W °75 MJ NEL (CH), or W/20 + 5 MJ day -1. Per kg fat-corrected milk (4% fat): 3.14 MJ N E L ( C H ) . Growth and fattening. Requirement is calculated on the basis of 0.330 W °~5 MJ day -1 for maintenance and REg for gain. As APL is seldom exactly 1.5, as accepted for NEV (CH)-system, difference between effective APL value and APL-- 1.5 is taken into account. So for total of maintenance and gain N E V ( C H ) =0.495 W°'75+ (RE~-0.165 W °75) k~,Jkg REg data are derived from feeding trials and it is assumed that kg can replace kf. See Table IV. Sheep. Maintenance: 0.228 MJ NEL (CH) kg- ~W °'75 Pregnancy: 60-kg ewe MJ NEL ( CH ) day- 1 Total required Month 1-3 5.7 Month 4 6.7 Month 5 7.3 Lactation: 4.7 MJ NEL (CH) kg- ~milk Growth and fattening: Table values only. For a liveweight gain of 200 g day-1, MJ N E V ( C H ) day- ~ requirements for lambs of liveweight W are: 20, 4.9; 30, 7.0; 40, 9.2. Goats. Data shown below. Maintenance: 0.24 MJ NEL (CH) kg- 1WO.75 Pregnancy: 1-3 months:+0.8 MJ N E L ( C H ) day-l; 4-5 months:+l.2 MJ N E L ( C H ) day -~.

267

Lactation: 2.7 MJ N E L ( C H ) kg -1 milk of 3% fat. Growth: 2-3 months 3.7 MJ NEL (CH) day-1; 4-5 months 4.3 MJ N E L ( C H ) day-l; 6-7 months 5.1 MJ N E L ( C H ) day -1.

References Bickel, H. and Landis, J., 1978 Schneeberger, H. and Landis, J. (Editors), 1984.

(15) Net energy lactation, NEL( YU), and net energy for growth and fattening, N E M ( YU), systems used in Yugoslavia since 1984 Net energy for lactation ( NEL (YU) as MJ kg- 1, calculated from ME. Net energy for growth and fattening ( N E M ( Y U ) ) , as MJ kg-1, calculated from ME.

Nutritive value Both values are calculated from ME values of feeds, using coefficients kin, k~ and kg as defined in the system used in The Netherlands (see p. 260).

Requirements Milk production. Maintenance in MJ: 0.293 W °75 NEL (YU), or W/20 + 5 MJ NEL(YU). Per kg FCM milk: 3.1 N E L ( Y U ) . See Table III.

Growth and fattening. Requirements for young animals expressed as MJ of N E L ( Y U ) , converted from UFL, (UFL=6.9 MJ N E L ( Y U ) ) as used in France. Requirements for older cattle are expressed as MJ of NEM (YU), converted from UFV, (1 UFV = 7.34 MJ NEM ( YU ) ) as used in France ( I.N.R.A., 1978 ). See Table IV.

Reference Obracevic, C., 1984. New Systems of Feed Evaluation, pub. Feed Manufacturers Association, Zagreb.

(16) Unit~tforaggere ( UF) used in Italy Up to 1986 Unith Foraggere (UF), as kg kg- 1, similar to Scandinavian feed units (SFU) based on Kellner starch equivalent (SEK). In 1986 the French system of UFL and UFV was adopted as the Italian system by the Commission "Feed evaluation" of the A.S.P.A. National tables are being prepared. See UFL and UFV system as used in France since 1978.

268

(17) Net energy for lactation, NEL ( H ), and net energy for beef, NEro and NEg, systems used in Hungary since January 1986 A multiple net energy system based on the U.S.N.R.C. dairy and beef cattle systems was introduced in January 1986. Net energy lactation ( N E L ( H ) ) expressed as MJ kg- ~dry matter, calculated from TDN or DE values. The van Soest and Sniffen modifications of the U.S.N.R.C. NEL (US) system for dairy cattle are used, in which NEL (US) values for individual feeds are discounted according to their cell-wall content. Net energy for beef and growing ruminants (NEro and NEg) are as N.R.C. 1984, converted to MJ kg- 1 dry matter, calculated from DE or ME values.

Nutritive value DE=0.1845 TDN% (MJ k g - l D M ) ME=0.82 DE (MJ kg-~DM) N E L ( H ) =0.6032 DE ( 1 - 2 d r ) -0.502 (MJ kg-~DM) where dr= discount factor for depressions in digestibility for feeding level above maintenance NEro = 1.37 ME - 0.033 ME 2+ 0.0006 ME 3_ 4.686 MJ dayNEg = 1.42 ME - 0.0416 ME 2+ 0.0007 ME 3_ 6.904 MJ day -

Requirements Milk Production. For maintenance: 0.3347 W °75 MJ day- 1 NEL ( H ) For each kg of fat-corrected milk: 3.10 MJ NEL (H).

Growth and fattening. For maintenance: 0.3222 W °75 MJ d a y - 1 NEro For liveweight gain: Medium-size bulls, Large-size bulls, Medium-size heifers, Large-size heifers,

N E g -- (0.20627 W °'~5) * ( L W G 1"°97) MJ day -1

NEg = (0.18280 W °'7~) • (LWG 1"°97) MJ day -1 NEg = (0.28702 W °'75) • (LWG 1"119) MJ day -1 NEg = (0.25439 W °'75) • (LWG 1"119) MJ day -1

References N.R.C., 1978. N.R.C., 1984. Van Soest, P.J. and Sniffen, C.J., 1979.

269

(18) Unitatilor nutritive la rumegatoare, UN(RO), new feed unit for ruminants), used in Rumania since 1983. Feed unit for ruminants (UN (RO)) kg kg- 1, based on a mean net energy in kcal kg-1 dry matter, divided by 2500 to give a ratio to the net energy of 1 kg of grain.

Nutritive value ME value is calculated as the mean value of the ME in the systems of F.R.G., U.K., U.S.A. and France as specified in Tables V and VIII. Net energy for ruminants (ENR) kcal kg-1 DM, is calculated as the mean value of: NEFr, Rostock; NEmp, M.A.F.F. 1975 at APL 1.5, converted to kcal; NEro and NEp, N.R.C. 1975/1976, calculated to NEmp at an APL of 1.5; UFL, I.N.R.A. 1978, converted to kcal; UFV, I.N.R.A. 1978, converted to kcal; New feed unit, UN ( RO ) = ENR/2500.

Requirements Milk production. For maintenance: 75.5 W °75 kcal day-~ ENR, or 0.0302 W °7~ kg U N ( R O ) day -1. For each kg milk: 106.4 fat%+323.2 kcal ENR, or 0.0426 fat%+0.1293 kg UN (RO) or 0.30 kg UN (RO) kg - ~FCM.

Growth and fattening. Maintenance, heifers 85 W °'7~ kcal day-1 ENR, bulls: 80 W °75 kcal day -1 ENR. For liveweight gain: Heifers ( 2.645 - 2.291 W+ 0.0109 W 2) .LWG kcal ENR day- 1 Bulls (1.106+9.157 W-0.0002W 2) .LWG kcal ENR day -1

Reference Burlacu, G., 1983.

(19) Oat feed unit, OFU, and metabolizable energy, ME( SU), systems in use in the U.S.S.R.. Oat feed unit, as kg kg - 1 feed. Metabolizable energy ME ( SU ) MJ kg- 1 feed.

Nutritive value Oat feed unit values are calculated from Kellner starch equivalent values SEK see p. 249, using 1 0 F U = 0.6 kg SEK. Metabolizable energy values are calculated from the EFr system as in Table V, converted to MJ (Schiemann, 1971, p.129).

270

Requirements Milk production. Maintenance: 5.1 kg OFU or 65 MJ of ME ( SU ) for a 600-kg COW.

Lactation: 0.5-0.55 kg OFU per kg FCM or 5-5.5 MJ M E ( S U ) kg -1 FCM, depending on yield level, see Table III.

Growth and fattening. Numerous tables published. See Table IV. Sheep. (1) Ewes: Maintenance and pregnancy. 60-kg liveweight.

Unit

Meat and wool ewes

First 12-13 weeks

OFU (kg) ME{SU) (MJ) OFU (kg) ME(SU) (MJ)

1.05 12.1 1.35 16.0

Last 7-8 weeks

( 2 ) Ewes: Lactation. 60-kg liveweight.

Unit

Meat-type ewes

First 6-8 weeks

OFU (kg) ME(SU) (MJ) OFU (kg) ME(SU) (MJ)

2.10 22.0 1.55 18.4

After 8 weeks

Reference Kalashnikov, A.P. and Kleimenov, N.I., 1985.

Appendix: Protein Systems for Ruminants In this section the authors have attempted to summarize the essential features of the protein systems now being used or implemented in several European countries. Particular use has been made of the review papers of Waldo and Glenn (1982a,b) in this respect.

(1) Degraded dietary crude protein/undegraded dietary protein, RDP/UDP, system used in the U.K. Crude protein XP g kg-1 DM; degraded dietary crude protein, RDP, g kg-1 DM; undegraded dietary protein, UDP, g kg -1 DM.

271

Nutritive value In situ measurement. From in situ dacron bag measurements of N loss from feed with time, Orskov and Mehrez (1977), corrected for outflow rate, (see section on measurement of protein degradability in ruminant feeds, p. 272 ). Then RDP =p XP g kg- ~DM, and UDP - XP - RDP g kg- ~ DM.

Calculation of dietary specification. RDP d a y - 1= 8.38 ME intake, MJ d a y UDP g d a y - l = 1.47 T P - 10.32 ME intake, MJ day -~ where TP is tissue protein, g day-1 XP g d a y - 1= RDP + UDP Degradability of dietary protein required, p-- RDP/XP.

Requirements Milk production. Maintenance protein, TP = 2.3 g kg- 1 W o.75g d a y - 1 Milk tissue protein, TP--3.3 g kg -1 milk Liveweight gain or loss, T P - - 150 or 112 g kg-1

Growth and fattening. Maintenance tissue protein, T P = 2.3 g kg- ~ W °75 g d a y - 1 Liveweight gain tissue protein, T P = 1 0 0 - 220 g d a y From equation: TP g day -1 =LWG(168-0.169 W+0.000163 W 2) (1.12-0.122 LWG)

References A.R.C., 1980. A.R.C., 1984.

(2) Protein digested in the intestine, PDI, system used in France, 1978-1988 Protein digested in the intestine (PDI) calculated from: (1) the N content of the diet (PDIN) g kg- 1 DM; (2) the DOM content of the diet (PDIE) g kg- 1 DM. This system was revised in late 1987 (see Addendum (I.N.R.A., 1987) ).

Nutritive value Calculation from the protein solubility. From the solubility ( S ) in buffer solution, corrected for differences with in vitro incubations in rumen liquor for particular classes of feeds.

272

Calculated from the tabulated true digestibility of proteins. From the tabulated true digestibility of dietary proteins in the small intestine (ddp) calculated from XP, S, DOM, indigestible organic matter, IOM and faecal protein, FP: ddp --

0.65 (1 - S) X P - ( F P - 0.025 D O M - 0.057 IOM) 0.65 (1 -- S) XP

From this is calculated the undegraded dietary protein which is truly digestible in the small intestine (PDIA) P D I A = X P ( 1 - S ) (0.65ddp), g kg -1 DM

Calculation from DOM and X P content. From the DOM and XP content of the feed are calculated two values for the microbial true protein which is truly digested in the small intestine ( P D I M ) . (1) PDIME, that owing to the energy content of the feed as indicated by DOM content: PDIME, g k g - 1= 75.6 DOM. (2) PDIMN, that owing to the dietary protein content (XP) g kg-~ DM and the solubility (S): PDIMN, g k g - l = X P ( 0 . 1 9 6 + 0 . 3 6 4 S ) . Then PDIN=PDIA+PDIMN, g kg-~DM and PDIE=PDIA+PDIME, g k g - 1 DM. The actual PDI content of a diet is the lowest of the separate summation of PDIN or PDIE values for the feeds comprising the diet. Requirements Milk production. Maintenance PDI = 3.25 g k g - ~ W °'75 g day- ~ for cattle. Milk PDI = 50 g kg - 1 FCM. Growth and fattening. Maintenance PDI -- 3.25 g k g - 1 WO.75 g day- 1 for cattle. Liveweight gain, PDI, g d a y - ~- protein content of gain/0.60 dayReferences I.N.R.A., 1978. I.N.R.A., 1987 (see Addendum). (3) Absorbable protein in the intestine, API, system used in Switzerland System is based on the French I.N.R.A. system, but without using PDIN. Minimum X P to energy ratios are specified instead. Absorbable protein in the intestine, API, g kg-1 DM.

273

Nutritive value The API value of a feed is calculated from: (1) digestible organic-matter content (DOM) kg kg-lDM; (2) crude-protein content, g kg-lDM; (3) degradability (D) calculated from solubility (S) as I.N.R.A. 1978: D=0.35+0.65S. Then API=75.6 DOM+0.8 X P ( 1 - D ) g kg -1 DM where 0.8 is the mean true digestibility of undegraded feed protein, DUDP/UDP. API values are only valid if the N requirements of rumen microorganisms are met. This implies at least 18-20 g XP MJ -1 N E L ( C H ) , or 10-12 g MJ -1 ME, depending on the class of livestock.

Requirements Milk production. Maintenance API = 3.25 g kg- ~ W °'75 d a y - 1 for cattle. Milk API = 50 g kg-1 FCM.

Growth and fattening. Maintenance API = 3.25 g kg- 1 WO.75g d a y - ~ for cattle. Liveweight gain API g d a y - l = protein content of gain/0.6 g day-1

Reference Landis, J., 1979. 1984.

(4) Crude protein flow at duodenum, XPD, system used in the F.R.G. Crude protein at duodenum ( XPD ) g d a y - 1.

Nutritive value The XPD value of a diet is calculated from: (1) metabolizable energy content, MJ d a y - 1; (2) undegraded protein content (UDP) g d a y - 1, calculated from tabulated data from in vivo measurements; (3) dry-matter intake, kg d a y - ~, from which endogenous contributions from the stomachs are calculated as 15.0 g XP kg-lDMI. Then XPD, g d a y - 1_- 11.92 ME + U D P - 15.0 DMI. With an adequate ME intake, XPD supply calculated from the above equation will be adequate unless degradability values (p) exceed the following values for dairy cattle: 0.88 at 15 kg FCM; 0.81 at 25 kg FCM; 0.75 at 35 kg FCM.

274

Requirements General. The following values have been adopted in calculating the X P D required for dairy cattle: ( M T P + U D P ) / X P D = 0.7; D M T P / M T P = 0.9; DUDP / U D P = 0.9; k~t-- 0.8. T h e n X P D , g d a y - ~= T P × 1.25 × 1.11 × 1.43 = 1.984 TP. Milk production. Maintenance tissue protein, T P , g day -~ =6.25 ( E U N + D N L + M F N ) where E U N , endogenous urinary N loss = 5.92 log W - 6 . 7 6 g day-1 DNL, dermal N loss = 0.018 W °'75 g day -1 M F N , metabolic faecal N loss = 2.91 g kg-~ D M I Milk protein, T P = 34 g k g - ~ F C M Liveweight gain tissue protein, T P = not stated. For a 600-kg dairy cow with no change in body protein, crude-protein at duodenum ( X P D ) requirements are calculated to be as follows: Milk yield (kg FCM day -1 )

XPD requirement (gday -1 )

10 15 20 25 30 35

1255 1665 2060 2465 2875 3270

Growth and fattening. A crude protein supply of 12 g X P M J - 1 M E appears to be sufficient, for all feeding conditions, after allowing for the recycling of about 0.3 g N M J -1 ME. N o t less than 90 g X P k g - l D M should be fed. Detailed requirements for fattening are not yet published. References Anschuss fur Bedarfsnormen (1986). Rohr, K. et al. (1986}.

(5) Amino acids truly absorbed/protein balance in the rumen, AAT/PB V, system used in Denmark, Finland, Iceland, Norway and Sweden since 1986. Amino acids truly absorbed in the small intestine: ( T y n d t a r m e n ) , AAT, g kg -1 DM; protein balance in the rumen ( V o m m e n ) , PBV, g kg -1 DM.

275

Nutritive value The AAT value of a feed is calculated from: (1) microbial true protein ( M T P ) synthesis from digestible carbohydrate (DCHO) defined as the sum of digestible crude fibre (DXF) and digestible N-free extract (DXX) i.e. D C H O = D X F + D X X . Then M T P = 0 . 1 0 6 DCHO g k g - 1 DM; ( 2 ) true digestibility of M T P in small intestine, D M T P / M T P = 0.85; ( 3 ) crude protein, (XP) content of feed, g k g - 1 DM; (4) degradability (p) of feed XP, as measured by the in situ dacron bag technique of Kristensen et al. (1982 ), and corrected for an outflow rate of 0.08 h - 1, as Orskov and MacDonald (1979) (see p. 272 on measurement of feed degradability). T h e n undegraded crude protein, UDP = X P (1 - p ) ; (5) true protein ( T P ) proportion within X P content of feed, T P / X P ; (6) digestibility of UDP, D U D P / U D P = 0.82. T h e n AAT, g k g - 1 DM = 0.106 DCHO+0.82 UDP× TP/XP where T P / X P is 0.85 for concentrates and 0.65 for roughages. The PBV value of a feed is calculated from: (7) microbial crude protein (MXP) synthesis, calculated from M T P (1) above, where M T P / M X P - 0.70. (8) rumen degradable crude protein (RDP) calculated from XP content and degradability (p) as in (3) and (4) above: RDP = XP ×p. T h e n PBV g k g - 1 DM-- R D P - 0.179 DCHO. Requirements Milk production. Maintenance AAT-- 3.3 W °'75 g day- 1 Milk AAT = 45 g k g - 1 FCM. Maintenance + milk production PBV = - 200 g day- 1. Growth and fattening. Not yet published. References Kristensen, E.S. et al. (1982). Protein Evaluation for Ruminants (1985). (6)) Absorbed true protein, AP, system used in the U.S.A. since 1985. Absorbed true protein (AP) g day- 1.

Nutritive vale The AP value of a diet is calculated from: (1) microbial crude protein ( M X P ) calculated from the NEL (US), TDN, (or

276

ME) content: MXP, g d a y - l = 7 1 . 6 N E L ( U S ) (Mcal) - 1 9 3 or M X P = 1 0 . 6 ME M J - 193. For diets with less than 40% forage, an alternative function is suggested, with a term for forage and concentrate intake as percentage of liveweight ( see N.R.C., 1985); ( 2 ) undegraded protein content ( UDP ) g day- ~calculated from in situ dacron bag measurements, corrected for outflow rate, as in the U.K. system; ( 3 ) metabolic faecal protein (FXP) g k g - ~ of indigestible dry matter (IDM) calculated from T D N value of diet: FXP = 90 (1 - 0.92TDN ) g day- '; The following values have been taken, in calculating the digested microbial true protein, D M T P or AP in this system, and digestible UDP, DUDP: M T P / M X P = 0.8; D M T P / M T P = 0.8; D U D P / U D P = 0.8. Then AP, g day= 0.64 M X P + 0.8 UDP - FXP.

Requirements General. The efficiency of capture of RDP by the microbes in the rumen is assumed to have a maximum value of 0.9: M X P / R D P = 0.9. Allowance is also made for the proportion of recycled protein N, RP, with the function R P = 1.22-0.012 XP+0.0000324 XP 2, which for XP levels of 100, 120, 140, 160 g kg -1 DM gives values for RP of 0.34, 0.25, 0.18 and 0.13, an alternative function is suggested, with team for forage then XP, g d a y - ~ = ( R D P + U D P ) / ( I + R P ) . Or assume value for recycled protein (RP) is 0.15, then XP, g d a y - l = ( R D P + U D P ) / 1 . 1 5 .

Milk production. Maintenance AP, g day- 1 = (EUP + DPL)/0.67 + M F P where EUP (endogenous urinary protein) loss = 2.75 W °5 g day- 1; DPL (dermal protein loss ) = 0.2 W °'6 g day- ' and 0.67 is the value for knm, the efficiency of utilization of absorbed amino acids for maintenance. Milk AP = milk protein 0.65g/kg-1 milk = 50 g kg-1 milk where 0.65 is the value of kn~,the efficiency of utilization of AP for milk protein synthesis. Live-weight loss AP, g day -1 = 160 g k g - ' , assuming an efficiency of 1.0 for mobilization and utilization of tissue protein.

Growth and fattening. Maintenance AP, g day -1 = ( E U P + D P L ) / 0 . 6 7 + MFP. Liveweight gain AP, g day- ~= tissue protein in gain/0.5 g daywhere T P is 140-160 g kg-* liveweight change, depending on liveweight, W, and 0.5 is the value of kng, the efficiency of utilization of AP for lean tissue deposition.

Reference N.R.C., 1985.

277 Addendum Revision of French energy and protein requirement systems for ruminants

As this chapter went to press, details were received of a comprehensive revision of the I.N.R.A. 1978 energy and protein requirements of ruminants, given in the Appendix to this Chapter. Full details are in I.N.R.A. 1978 and 1988. The main changes are briefly outlined below. Energy requirements Nutritive value Gross energy (GE). Roughages: new equation for grass silage GE = 3.910 + 2.450 X P + 169.6pH (values in organic matter) (kcal kg -1) Maize silages: 4678 kcal kg -1 OM if DM > 30%; 4772 kcal kg -1 OM if DM < 30%. Digestible energy (DE). Calculation of DE/GE: All previous equations replaced with feed/species-specific equations. Metabolizable energy (ME). Calculation of ME/DE M E / D E = 0.8417 - 9.9 × IO-~XF - 1.96-4XP + 0.0221NA (on OM basis) NA = niveau d'alimentation, or feeding level, FL) UFL (kg kg -1) = NE~/1700 (net energy of barley), was 1730 kcal kg -1. UFV (kg kg-1 = NEmJ1820 (net energy of barley), was 1855 kcal kg-1. Requirements Milk production. For each kg fat-corrected milk (4% fat): 0.44UFL (was 0.43). For each kg liveweight gain, add 4.5UFL (was 3.5). Corrections made to the total ration have also been modified. Growth and fattening. Revised factorial method, based upon breed, sex and rearing system. (1) Sheep. Factorial requirements for pregnancy and lactation vary with weight and number of foetuses carried, or lambs suckling. (2) Goats. Maintenance: 0.0384 UFL kg-1 WO.75 Lactation: 0.385 UFL kg-1 milk of 3.5% fat (was 0;41) Pregnancy: 0.0095 UFL kg-1 WO.V5during last 5 weeks Weight gain: 3.9 UFL kg-1 gain

278

Growing kids: Age (months)

Weight (kg)

Weight gain (g day-1)

UFL day-1

1 3 5 7

6.5 16.3 24.5 30.0

165 155 115 70

0.42 0.55 0.66 0.69

Protein requirements N u t r i t i v e value

Calculated from (1) XP content, (2) fermentable organic matter, (FOM), where F O M = D O M - U D P - X L - fermentation products in silage, (3) standardised degradability measurements, (p), with nylon bags, (4) true digestibility of dietary protein in the small intestine, (dr), calculated from new data, ranging from 0.55-0.95. (5) true digestibility of microbial protein (80% of XP): 0.80. Revised equations for PDIA, PDIMN a n d P D I M E are given P D I A = 1.11 ( 1 - p ) d r × X P P D I M N = 0.64 (p-0.10) X P P D I M E = 0.093 F O M Calculation of PDIN and PDIE remains as before. Requirements M i l k production.

Milk PDI = 48g kg -1 (was 50) (based on knl = 0.64, was 0.67)

G r o w t h a n d fattening.

Protein content of gain defined by factorial approach

and tables. knp = 0.50 in cattle, 0.42 for sheep. kng varies 0.28-0.68, with breed, sex and liveweight (was 0.60).

Pregnancy.

References I.N.R.A., 1987. R. Jarrige (Editor), Alimentation des ruminants: revision des syst~mes et des tables de I'I.N.R.A. Bull. Techn. No. 70. CRZV, Theix, I.N.R.A., 217 pp. I.N.R.A., 1988. R. Jarrige (Editor), Alimentation des bovins, ovins et caprins. I.N.R.A., Paris, 370 pp.

Livestock Production Science, 19 (1988) 279-288

279

Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

III. 3. N o n - R u m i n a n t Herbivores; Horses and Rabbits III.3.1. H o r s e s

J.L. TISSERAND

INTRODUCTION The horse is an herbivorous animal which principally digests cytoplasmic and reserve carbohydrates, proteins and lipids in the same manner as a pig. Besides, the a b u n d a n t bacterial population in its large intestine permits the horse to use structural carbohydrates to some extent, mainly for energy supply. H o w energy-yielding nutrients are divided between the two parts of the digestive system remains uncertain, b u t it may vary with the rhythm of feed distribution. It is generally admitted that cereals and concentrates are degraded for the greater part in the small intestine, whereas forages, rich in cell walls, are degraded in the large intestine. Table I shows estimates of the site of digestion and net adsorption, as reported by Hintz (1977). The stomach of the horse is not very voluminous: less than 10% of the total volume of the digestive tract. In contrast, the large intestine (caecum, colon) is very well developed: 60% of the total volume of the digestive tract. This organ is the site of microbial digestion, similar to the rumen function in ruminants. As in ruminants, volatile fatty acids: acetic, propionic and butyric acids, are TABLE I Estimates of site of digestion and net absorption (Hintz, 1977) Dietary fraction

Small intestine (%)

Caecum and colon (%)

Protein Soluble carbohydrates Fiber Fats Calcium/magnesium Phosphorus Vitamins

60-70 65-75 15-25 Primary 90-99 20-50 Primary

30-40 25-35 75-85

0301-6226/88/$03.50

© 1988 Elsevier Science Publishers B.V.

1-10 50-80

280 TABLE II Mean digestibilityof organic matter of various feedstuffsin horses and ruminants (Loeweand Meyer,1974)

Straw Hay Greenforage Oat Other cereals Fodderbeet

Horse (%)

Ruminant (%)

35 50 65 70 80-85 85

50 55-6O 70 70 80-90 85-90

produced there by fermentation. Normally, their ratios are 75:15:8. Depending on the proportion of concentrate in the diet the ratios may shift and in exceptional cases (rations with abundant starch content) lactic acid may be produced in addition. Differences between horses and ruminants with regard to apparent digestibility are shown in Table II. The apparent digestibility of organic matter is quite similar for horses and ruminants. For protein, differences between horses and ruminants regarding the site of microbial proliferation have to be considered. Absorbability of feed protein by horses is about 10 percentage units lower than apparent digestibility (Jarrige and Tisserand, 1984). Feeds pass through the digestive system of the horse in an average period of 2-3 days. Rate of passage depends on composition and volume of the ingested feeds. When the ration is voluminous, the ingesta arrive in the caecum 1.5-2 h after the beginning of the meal. When concentrates precede forage, the average time of passage to the caecum is about 9.5 h. Information on the specific phenomena of digestion in horses was scarce until some years ago. Specific feed-evaluation systems for horses were not available and therefore, in many countries, feed rationing for horses was defined by analogy with ruminants, particularly with bovines. A number of similarities, as mentioned above, in the digestive process of horses, mainly heavy breeds for work, and bovines were the obvious reason to do so. However, in the last 15 years specific studies have been carried out in various countries. Knowledge of the digestive mechanism in horses has grown considerably in this period and has resulted in adequate methods for evaluating nutrient supplies and requirements for energy and protein. Generally, horses are fed with the same type of feedstuffs as ruminants: forages with varying fiber contents, supplemented with concentrates for particular performances, such as riding, racing, jumping and so on. The units used in feed evaluation in horse feeding are based on the principles

281 described in Chapter III.1 (Bickel, 1988). As with ruminants and pigs, various feed-evaluation systems are in use in various countries in Europe. SYSTEMS OF FEED EVALUATION

Energy Historic systems From the beginning of the century onwards, when the systems for estimating energy supply and expenditure were being developed, values calculated for the large ruminants (bovines) were applied to horses. In many countries, the starch unit or the Scandinavian unit, referring to the net energy of potato starch or to that of barley were used; sometimes they are still used. Present systems Present systems are mainly, but not always completely, based on experimentation with horses. Digestible energy N.R.C. (1978) proposed a system which starts with the ruminant T D N values of feedstuffs. The value is multiplied by 4.0 for forages and by 4.41 for other feedstuffs, resulting in DE values for horses, expressed in kcal. Loewe and Meyer (1974) used a similar approach, but expressed DE for horses in Mcal instead of kcal. Net energy The research workers of the Oskar Kellner Institute in Rostock (G.D.R.) (Laube, 1977) recommend the use of the feeding value 'Netto Energie-Fett Rind' (NEFf), expressed in terms of fodder units EFt. Thus, the same method of calculation is used as for ruminants, although the system is not specific for horses. 1 EFt is equal to 10.5 kJ or 2.5 kcal NEFf. In France, feed values are expressed in terms of horse feed unit (HFU) corresponding to the net energy value for the maintenance of 1 kg barley, i.e. 9.2 MJ or 2200 kcal (Vermorel et al., 1984). H F U is calculated from specific digestion experiments on horses. To evaluate the net energy of barley for maintenance the following relationships are assumed: DE--0.82 GE; ME = 0.90 DE; N E = 0 . 7 8 ME. For practical rations, consisting of 75% forages and 25% concentrates, as a reference, the following relationships are accepted for the HFU system: DE = 0.67-0.83 GE; ME = 0.83-0.91 DE; NE = 0.63-0.80 ME.

282

Protein In most countries, the evaluation of the protein value of feedstuffs is expressed in terms of digestible crude protein (DXP), derived from the measurement of the apparent digestibility in the horse. However, evaluation as D X P does not discriminate between the amino acids and the non-protein nitrogen ( N P N ) fraction, the latter being absorbed as ammonia, which does not contribute to the protein requirement. Besides, D X P gives no information on the site of the absorption of nitrogen, i.e. in the small and in the large intestine. This is the reason why some authors recommend considering only the true protein fraction of the feeds and estimating the digestible {rue protein (DTP) (Wolter, 1975 ). But these systems do not account for protein degraded in the large intestine. Therefore, the H D X P system, as recommended in France, accounts for the protein, which is actually digested and absorbed in the small intestine, and for possible absorption of some amino acids in the hind gut. Thus determined H D X P values are recommended to be reduced by the following percentages (Jarrige and Tisserand, 1984): 10% for green forages; 15% for hay and dehydrated fodder; 30% for correctly-conserved grass silages. These corrections make allowance for the lower contribution of absorbable amino acids from roughages than from concentrates. However, none of the present systems considers the specific requirement of the horse for essential amino acids. NUTRIENT REQUIREMENTS

Energy requirement In horses, as for other livestock, total energy requirement is split between requirement for maintenance and for production, whatever it is. Apart from growth and reproduction (primarily pregnancy and lactation) horses have a significant specific requirement for muscular activity. Intensity of this activity is variable and ranges from riding~o racing and traction. TABLE III Energy requirementsfor maintenance (kJ

kg-1 WO.75) of horses

in variousenergysystems

DE

ME

NE

NRC (1978) . Loeweand Meyer (1974)

649 573

-

-

Vermorel et al. (1984)

586

502

351

283 Maintenance Maintenance requirements depend in a broader sense on the horse's personality and the environment in which it lives. Thus recommendations for energy requirements for maintenance may vary, as shown in Table III. Work Recent studies have evaluated the energy needs resulting from muscular work quite precisely. Not only the nature and importance of the work done are taken into account, but also the animals training and environment (Hintz, 1983). The amount of energy used during any physical activity depends on the muscular work intensity. For a moderate activity, e.g. a trotting speed of less than 300 m min-1, aerobic muscular fibers, mainly use glucose and long-chain fatty acids as energy sources. During a period of intense activity, the anaerobic muscular fibers, which contract rapidly, transform glucose into lactate, the accumulation of which in a muscle results in tiredness. Training increases the metabolization of fat reserves which are degraded into non-esterified fatty acids and diminishes the transformation of glucose into lactate. When the muscular effort required is brief and intense a diet rich in sugar and starch helps make glucose available in the muscles. In any case an excess of crude protein, which diminishes muscular work efficiency, must be avoided. For walking, energetic consumption is on average 1.5 J kg -~ bodyweight (W) for each horizontal meter and 29 J kg-1 W for each vertical meter. When speed increases, so does the amount of energy used. For pulling, requirement varies with speed, distance and the weight of the load to be pulled. Gestation During gestation the amount of energy stored in the uterus (foetus and annexes ) is about 4.2 MJ. Generally, the weight of conception products amounts to 10% of the mare's liveweight. It is, however, slightly higher, 12%, when mares weigh less than 400 kg. Since the foetal development takes place mainly during the last 4 months of gestation, it is recommended to add 1.5-3.6 MJ NE day- 1 during this period for a saddle mare and 2.1-5 MJ NE day -1 for more heavy breeds. Lactation Lactation requirement depends on milk composition and the quantity of milk produced. Mares' milk has a low energy content of 2.3-2.5 MJ k g - 1 owing to a very low fat content of 10-15 g kg -1. The corresponding allowance accounts for 3-4 MJ DE kg-1 milk. During a 5-6-month lactation period the mare produces an average of 10-30 kg milk daily with a maximum around the eighth week. This is an increase of 10% in comparison with the onset of lac-

284 tation. Milk production may be approximately estimated to be 3% of the saddle mare liveweight, 2.5% of heavy breeds and 5% of ponies. Growth Requirement for growth depends on the growth rate and the composition of liveweight gain. The foal's growth during the first weeks is very important. Thus the birth weight is about doubled within 1 month depending on the mare's milk production. From the third month on, the growth rate is reduced owing to a decrease in the mother's milk production, which is not completely compensated for by the intake of grass. At weaning the 5-6-month-old foal weighs 40-45% of its adult weight, i.e. 200-250 kg for a saddle horse and 300-400 kg for a heavy breed. At the age of 2 years, its weight is 70% of its adult weight, which is reached at the age of 3.5-5 years, depending on the frame. Fat content increases with age, whereas the protein content of the fat-free weight remains constant. Stallions during the mating season Semen production requires supplementary energy, depending on the intensity with which the animal is used. It is recommended to increase the allowances for draught, saddle and pure-bred stallions by 10, 15 and 20% at rest and 25, 30 and 35% during the mating season, respectively. Recommended energy allowances are shown in Table IV. Protein In horse nutrition, as for other species of domestic animals, protein plays an important role. Tissue renewal and the functioning of the organism call for a permanent supply of proteins and amino acids, to be met daily or in some cases, at least, in the longer term. Although amino acid supply is crucial, the requirement is mostly expressed as digested protein. No specific recommendations for essential amino acids are available. As for other animals, the factorial approach to requirement is common practice. Work The amount of protein used as a result of muscular work is not known exactly. It is probably low. The increased energy expenditure due to muscular work is not accompanied by a proportional increase in protein expenditure. Nitrogen loss by enhanced perspiration seems to be compensated for, by a surplus of protein in the diet, or by microbial degradation of unabsorbed protein. This surplus is often caused by feeding higher amounts of concentrates to cover enhanced energy requirement, without reducing the protein content of the concentrate. The surplus, however, might reduce the energetic efficiency of work.

285 TABLE IV Recommended energy allowances above maintenance for various performances and in various systems in horses Reference

Digestible energy~ N.R.C.

Work (kJ kg -1W h -i) Walking 2.1 Slow trotting 21.3 Fast trotting 52.3 Galloping/jumping 100 Gestation (kJ mare- 1day- 1) last 4 months 8860 Lactation 3310 (kJ kg -1 milk) Growth 5-9.5 (kJ g - 1W gain )

Net energy

Meyer

Pagan and Hintz

6.3 21.3 52.3 100

7.1-10.5 27.2 57.3 81.6

Vermorel et al. 8.6-14.2 20-40 b 52-80 c 59-92 d

Vermorel et al. 5.5-9.1 12.8-25.6b 33.1-51.5 c 37.8-58.8d

3200-3640 f

-

180-15780e 4440

4600-101004~ 2840

6.7-10.5

-

28.8-57.5 g

18.4-36.8g

aSources: NRC (1978); Loewe and Meyer (1974); Pagan and Hintz ( 1986); Vermorel et al. (1984). bLight work outside. CMedium work. dIntensive work outside. eSecond value refers to the last 4 months of gestation. fMargin according to variable k,. g400 kg W of the foal; gain of W=0.5 and 1 kg day -1, respectively. Higher values are recommended for racing horses.

Gestation and lactation A p r o t e i n - d e f i c i e n t diet d i m i n i s h e s fertility. T h e d e v e l o p m e n t of t h e foetus entails a n i m p o r t a n t p r o t e i n r e q u i r e m e n t in t h e t h i r d p a r t of gestation. T h e p r o t e i n a c c r e t i o n in t h e foetus a n d m a t e r n a l tissues has b e e n m e a s u r e d b y M e y e r a n d Ahlswede (1976). It a m o u n t s , for a m a r e of 500 kg W, to 1.3, 2, 2.2 a n d 2.8 kg d u r i n g M o n t h s 8, 9, 10 a n d 11 of gestation, respectively. H o w e v e r , the effects of t h o s e r e q u i r e m e n t s are m i n i m a l as far as p l a n n i n g is c o n c e r n e d , because a n a b o l i s m of p r e g n a n c y seems to be m o r e efficient t h a n of m u s c u l a r growth. T h e p r o t e i n c o n t e n t of m a r e s ' milk is relatively low a n d does n o t v a r y m u c h ( 2 0 - 2 5 g k g - 1 ) , e x c e p t d u r i n g t h e colostral phase. L a c t a t i o n r e q u i r e m e n t dep e n d s on milk o u t p u t , a l t h o u g h n o t i c e a b l e a m o u n t s of b o d y p r o t e i n reserves can be mobilized b y t h e m a r e to c o v e r her r e q u i r e m e n t for g e s t a t i o n a n d lactation. T h i s a p t i t u d e p e r m i t s some savings to be m a d e d u r i n g w i n t e r b u t n o t too m u c h a d v a n t a g e s h o u l d be t a k e n of it, because p r o l o n g e d n e g a t i v e - p r o t e i n b a l a n c e can r e d u c e t h e foal's weight a n d vitality at birth. T h e r e f o r e , recomm e n d e d n u t r i e n t allowances are usually c a l c u l a t e d to m a k e up for a l m o s t all

286

needs without using reserves. They take into account the quantities which go to the uterus and the udder and 45-55% efficiency of the use of amino acids by the pregnant or lactating mare.

Growth Protein requirements for growth vary with the importance of the liveweight gain, which contains about 22% of crude protein in the fat-free tissue. But, as the amount of fat in the gain increases with age, it diminishes for each kg weight gain as the animal becomes older. Accordingly, the requirement of DXP per kg liveweight gain diminishes with the age of the animals. Besides, a specific need for some essential amino acids must be taken in account. Stallions The protein requirement for semen production is negligible. Some authors however, propose an additional daily allowance of 200 g of digestible crude protein. Recommended allowance of protein for maintenance, pregnancy, lactation and growth is shown in Table V. No specific allowance is given for reproduction. Horse feeds Forages are traditionally used to feed horses. This herbivore is very sensitive to the quality of the herbage and in particular when the plant is at the growing stage. Grazed herbage at the pre-flowering stage of the grass allows a daily consumption of 90-100 kg whereas 2-3 weeks later at the flowering stage, consumption decreases to 50-60 kg. For grazing, horses prefer polyphyte meadows with 70-80% gramineae, TABLE V Protein allowances for horses Reference

Maintenance (g kg -~ W 0'75) Reproduction (mare) Pregnancy (g kg -1 W) Lactation (g kg - ~milk) Growth (g kg -1 W)

Digestible crude protein"

HDXP

N.R.C.

Jarrige and Tisserand a

3 0.18-0.20 32-45

Meyer 3

40-50 0.16-0.25

~Sources: N.R.C., (1978); Loewe and Meyer, (1974); Jarrige and Tisserand (1984). bHDXP = horse digestible crude protein.

b

2.8 0.17-0.37 40-55 0.37-0.44

287 10-15% leguminous plants and 5-10% other species. Coarse plants are little liked by horses and limit the fodder intake, which should be avoided. Whereas, unlike ruminants, horses can be given coarse pelleted, dehydrated forage without any problem, the use of badly-preserved hay, whitish or greyish, mouldy, or dirtied with earth results in colic and sometimes abortions. Feeding of wet or highly-lignified hay should be avoided as well. Silages can be used, but these must be very well preserved. Straw should be presented in racks. Alfalfa is especially recommended by some authors for stallions during the mating season. Although forage constitutes the basis of any diet, a concentrate, which can make up an important part of the diet of race horses, must be added. Cereals and oil meals or oil cakes can be used, often having been pressed or crushed and sometimes soaked and cooked. Oats and linseed cakes are often regarded as highly-recommended feeds for horses. Most of these recommendations are more a result of tradition than of scientific observation. Among other feeds, which can be given to horses, carrot and beet roots, industrial by-products, such as bran, beet pulp and, preferably dehydrated, brewery drafts can be used. Concerning the protein supply given to growing foals and brood mares by-products of animal origin should be used rather than proteaginous seeds. Poisonous plants must be avoided. These are, in meadows: buttercups, anemones, spurges, autumn crocuses and ragworts. Poisonous in hedges are fern, digitalis and deadly nightshade. Poisonous trees are false acacias, tuyas, yews and privets. CHANGES IN THE FUTURE After the big decrease in the number of horses owing to mechanization, particularly in Western Europe, it seems that the horse population in Europe may remain constant in the future. Maybe a slight increase in the number of saddle horses may be expected. Future research work should give us more information about the protein requirements of the horse, in particular concerning essential amino acids for growing foals, brood mares and perhaps stallions during the mating season. More information is needed about the energy expenditure of sporting animals. The percentage of concentrate and, to a certain extent, that of industrial byproducts, offered as compound feed may increase, to the detriment of forages.

REFERENCES Bickel, H., 1988. Feed evaluationand nutritional requirements.Introduction. Livest. Prod, Sci., 19: 211-216. Hintz, H.F., 1977. Nutrition of the Horse. In: J.W. Evans et al. (Editors), The Horse. Freeman, San Francisco.

288 Hintz, H.F., 1983. Nutritional requirements of the exercising horse. In: D.M. Snow, S.G.B. Peisson and R.J. Rase {Editors), Equine Exercise Physiology. Grante. Edition Cambridge, pp. 275-290. Jarrige, R. and Tisserand, J.L., 1984. M~tabolisme, besoins et alimentation azot~e du cheval. In: R. Jarrige and W. Martin-Rosset (Editors), Le Cheval, Reproduction, S$1ection, Alimentation, Exploitation. I.N.R.A., Paris, pp. 277-302. Laube, W., 1977. Das DDR-Futterbewertungssystem. VEB Dtsch. Landwirtsch. Verl. Berlin, 824 pp. Loewe, H. and Meyer, H., 1974. Pferdezucht und Pferdeftitterung. Ulmer, Stuttgart, 387 pp. Meyer, H. and Ahlswede, L., 1976. Ueber das intrauterine Wachstum und die K~rperzusammensetzung von Fohlen sowie den N§hrstoffbedafftragender Stuten. Ueber Tierernaehr., 4: 263-292. N.R.C., 1978. Nutrient requirements of domestic animals. No. 6. Nutrient requirement of horses, 4th edn., Washington DC. pp. 2-10. Pagan, J.D. and Hintz, H.F., 1986. Equine energetics. II. Energy expenditure in horses during submaximal exercise. J. Anim. Sci., 63: 822-830. Vermorel, M., Jarrige, R. and Martin-Rosset, W., 1984. Mdtabolisme et besoins Snerg~tiques du cheval, le syst~me des UFC. In: R. Jarrige and W. Martin-Rosset (Editors), Le Cheval, Reproduction, Sglection, Alimentation, Exploitation. I.N.R.A., Paris, pp. 239-276. Wolter, R., 1975. L'alimentation du Cheval. Vigot Frbres, Paris, 2nd edn., 177 pp.

Livestock Production Science, 19 (1988) 289-298

289

Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

III. 3 . 2 . R a b b i t s

F. LEBAS

INTRODUCTION

Experimental work conducted in Europe and throughout the world during the last 15 years has allowed the definition of reliable recommendations to be used in feeding rabbits for meat production, under temperate European conditions. Several reviews of published literature have been made recently (Lang, 1981; Lebas, 1983; I.N.R.A., 1984). The feeding of rabbits has to take into account various special features of anatomy and feeding behaviour of this animal: (1) the digestive system with a relatively big stomach and the voluminous caecum where microbial digestion takes place; (2) the frequent intake (30-40 times a day) of small amounts of feed (2-8 g per meal) in a short time (4-6 min per meal) (Prud'hon et al., 1975). The traditional method of feeding rabbits for meat production was to rely on cereals, bran and forages which were fresh during the summer and dried during the winter. During this latter period, farmers also used fodder beet and carrots. Currently, this means of feeding is rapidly declining but it is still used for up to one third of the rabbits produced in France, for example. On intensive farms, which represent the major type of commercial production, rabbits are fed compound balanced diets. With this change in the feeding systems, which went along with the intensification of meat production, one has to pay attention to the bulkiness of the diet, besides the usual allowance for energy, protein and minerals. One should also keep in mind here, that the average transformation ratio of plant protein to animal protein by rabbits is 18% with fibrous materials, whereas this ratio is increased to 22% in the most efficient rabbitries. FEED EVALUATION

The energy value of feeds is usually evaluated as digestible (DE) or metabolizable (ME) energy, considering ME/DE equal to 0.94. Digestibility of feed is most likely to compare with that of pigs (Nehring et al., 1963 ). However, the results of digestibility experiments are somewhat conflicting. Some authors claim a reduced digestibility especially of crude fiber (Jentsch et al., 0301-6226/88/$03.50

© 1988 Elsevier Science Publishers B.V.

290 1963), compared to the digestibility in horses, whereas former experiments showed higher digestibility of organic matter at a high level of crude fibre (Axelsson, 1942). The conflicting results may stem from differences in cell-wall constituents. Within diets currently utilized, the low digestibility (10-30%) of cell-wall constituents associated with raw materials such as lucerne or straw, means that such materials only have a minor role in meeting energy requirements when compared with starch. On the other hand, cell-wall constituents from those plants that are only slightly lignified (usually young plants) have a considerably higher digestibility (30-60%) and their contribution to overall energy requirements may be 10-20% and up to 30% under the most favourable conditions. Some experimental efforts have been made to predict the digestible (or metabolizable) energy content of a diet from its chemical analysis (Battaglini and Grandi, 1984; De Blas and Santoma, 1984). In all cases, cell-wall constituents are the most explicative analysis for energy digestibility; for some researchers aciddetergent fibre (ADF) is the more suitable analysis but for others neutral detergent fibre (NDF) is better (Pagano-Toscano et al., 1985). At present, none of these equations is precise enough to be employed in practice. Therefore the DE content of rabbit feed is usually calculated by using the DE value estimated as for pig feedstuffs. According to Jentsch et al. (1963) digestible energy of rabbit feeds may be calculated as follows if digestible crude proteins (DXP), lipids (DXL), fiber (DXF) and nitrogen-free extract (NFE) (DXX) concentrations are known: DE (MJ kg -1) =21.95 D X P (kg kg -1) +39.62 D X L (kg kg -1) + 17.22 D X F ( kg kg- 1) + 17.39 D X X ( kg kg- 1) The protein value is based, in general, on crude protein and amino-acid content. Digestibility is generally assessed as the difference of nitrogen intake and nitrogen output in the hard pellets of the faeces. Thus, coprophagy of caecotrophe pellets is not prevented and the protein of these pellets is correctly considered as digestible. These pellets contain 350-450 g XP kg- 1DM, whereas unpalatable hard pellets contain between 100 and 200 g XP kg- 1 DM ( Proto, 1980). The digestibility of vegetable fat (e.g. soya bean oil) is comparable with data from pigs, although Nehring et al. (1963) show lower digestibility of fat in concentrates than for pigs. Pure animal fats have a lower DE content than fats of plant origin ( Maertens et al., 1985 ). NUTRIENT REQUIREMENTS Nutrient requirements and the recommendations of nutrient allowances may be distinguished for four categories of rabbits: (1) adult rabbits at mainte-

291 nance (males, non-reproducing does, those to be culled); (2) pregnant does (but not lactating); (3) lactating does (pregnant or not); (4) young rabbits between weaning ( around 1 month) and slaughter at about 2.5 months.

Energy The energy requirement of adult rabbits at maintenance varies according to different authors. Experiments in respiration chambers resulted in a daily maintenance requirement of 395 kJ DE kg- 1 WO.75 ( Schiirch, 1949 ). However, allowances for practical feeding at maintenance are much higher, e.g. 485 kJ and about 600 kJ DE kg -1 W °'75 according to Parigi-Bini and Xiccato (1986) and Jeroch (1986), respectively. The requirement for pregnant does is enhanced during the last 10 days before parturition by about 30%, but the spontaneous daily intake decreases during the same period by 10% (Lebas, 1979). Rabbits are generally fed ad libitum and regulation of intake is possible if dietary energy concentrations are between 9.2 and 13.0 MJ DE kg-1. With growing rabbits (0.5-2.5 kg W) as with lactating does (8 young suckled), the daily intake is 900-1000 kJ DE kg -1 W °75, i.e. about twice the maintenance requirement. Milk production of lactating does lasts about 30-50 days, with peak production during the third week. Does' milk is about two and half times more concentrated than cows' milk. The concentration varies considerably during the first week of lactation. In peak lactation, rabbit milk consists of about 260 g DM, 130 g protein, 90-100 g fat, 10 g lactose, 22 g minerals and 7.0-7.5 MJ energy per kg (Lebas, 1971). The amount of milk produced depends on the number of offspring. Forty to 50 g milk day- 1 kg- 1 W of the doe is a fair value and daily performance of 100-300 g is often achieved (Coates et al., 1964; Cowie, 1969; Lebas, 1971 ). Partial efficiency of utilization of metabolizable energy for milk production (kl) is about 0.6-0.7. Body reserves can only be mobilized marginally for milk production, owing to relatively small reserves (Lebas, 1971, 1973a). The composition of tissue accretion in growing rabbits is relatively high in protein and low in fat content, i.e. about 210 g protein, 35 g fat and 6.6 MJ energy per kg liveweight gain (LWG) ( Schiirch, 1949).

Dietary bulk In contrast to other farm animals, recommendations are given not only for crude fibre but also for indigestible crude fibre. This refers to the role of dietary bulk. Cell-wall constituents play an important role in providing bulk to the diet. Although the analytical technique is imprecise, assessment is generally satisfactorily achieved by the crude-fibre method. To ensure an adequate level of

292 bulk, a dietary crude fibre level of 13-14% appears sufficient for the young growing rabbit, if a minimum level of 10% indigestible crude fibre is allowed. For lactating does a slightly lower crude fibre level (10-11% ) is acceptable. The bulkiness of the diet and the physical form in which it is presented will influence the dietary energy value of the remainder of the diet: with bulkier feeds the associated increase in rate of passage of digesta may reduce the digestibility of other energy-yielding ingredients, however, without influencing apparent protein digestibility. Transit time increases with the size of particles, which contain the cell-wall constituents. A very fine grinding of raw materials, e.g. sieve holes of 1 mm diameter, may induce a disturbance of the digestive tract motility, specially with highly-digestible fibre sources (Pairet et al., 1986). However, grinding of diets with small ( 2 mm) or wide ( 7 mm) holes, in a commercial factory, failed to induce any digestibility variation or health disturbance in growing rabbits ( Lebas and Franck, 1986; Lebas et al., 1986). Protein and amino acids

The sensitivity of the rabbit to dietary protein quality, for a long time controversial, is now accepted. The most recent work has shown that 10 amino acids are essential and that an eleventh, glycine, is semi-essential (Adamson and Fisher, 1973). Following what is known with other species, it could be considered that tyrosine and cystine might partially replace phenylalanine and methionine, respectively. In fact the possibility of replacing one sulphur amino acid by the other has been confirmed although no work has been carried out on phenylalanine and tyrosine. Amino-acid requirements for the rabbit have only been studied in practice with respect to lysine, arginine and sulphur amino acids (methionine and cystine), and recently to threonine and tryptophan (Berchiche, 1985). When expressed as a percentage of the diet, lysine and sulphur amino-acid levels should be around 0.60-0.65% for each, while that for arginine should be more than 0.8%. There is a considerable difference for lysine and arginine between these optimum levels and those which have a negative influence. However, with sulphur amino acids the margin between optimum levels and excesses is small. Higher levels entail poor performance. Minimum levels of other essential amino acids have simply been calculated from diets which give satisfactory performance. When dietary protein provides all essential amino acids, dietary crude protein levels need only be 15-16% for growing rabbits. For breeding does, optimum levels of crude protein are between 17 and 18% with a balance of essential amino acids according to those for a young growing rabbit. Precise requirements for most of the essential amino acids in does are

293 not known, but recent work of Maertens and de Groote (1986) indicates a tendency for positive performance with a higher lysine concentration (5% of proteins) for breeding does in comparison with growing rabbits (4% of proteins ). An increase in dietary protein level, to 21%, will raise milk production but will reduce slightly the number of rabbits weaned. A lowering of dietary protein level from 16 to 13% will reduce weaning weight without any appreciable alteration to fertility. In addition, it is known that the feed intake of a diet balanced with respect to essential amino acids is always higher than that with a similar but unbalanced diet. If the overall quality of dietary protein is insufficient, daily DM intake is correspondingly reduced. All preliminary studies investigating classical non-protein nitrogen ( N P N ) sources (urea, ammonium salts) have proved unsuccessful. This has been confirmed for the Angora rabbit by Teleki et al. (1983), but according to recent work of Proto et al. (1987), N P N with a medium hydrolysis rate such as biuret, may be utilized by growing rabbits. This is to be confirmed before practical application can be recommended. Minerals and vitamins

Calcium and phosphorus requirements of growing rabbits are considerably lower than those of the lactating does. Significant amounts of minerals are excreted through milk: 7-8 g minerals daily at peak lactating, containing 1.5-2 g calcium. An excess (1.0%) or a lack (0.42% of the diet) of phosphorus induces a significant alteration of fertility (Lebas and Jouglar, 1984 ). The breeding doe is more tolerant to the calcium level of the diet, but the best range is 1.0-1.5%. Cheeke et al. (1985) showed that the calcium in ground limestone is of greater availability (81%) than the dicalcium phosphate or the calcium in alfalfa meal ( 54% for both). Phytate phosphorus of cereals, cereal by-products and soya bean meal is available for the rabbit ( Cheeke et al., 1985; Nelson et al., 1985). An imbalance in dietary levels of sodium, potassium and chloride may promote nephritis and reproductive problems, a risk which is particularly important with those plants, especially lucerne, that are grown with high levels of potassium-containing fertilizers. A growth-promoting effect of high dietary levels of copper ( 200 ppm) has occasionally been observed. The microflora within the digestive tract synthesizes important amounts of water-soluble vitamins, which the rabbit is able to utilize by ingesting caecotrophe pellets. In this way, requirements of all B-group vitamins and Vitamin C for maintenance and for an average production level may be met. On the other hand, very fast-growing animals will respond to supplements of Vitamins B1, B6 (1-2 ppm), B2 (6 ppm) and nicotinic acid (30-60 ppm) to the diet. Dietary levels of up to 1% Vitamin C will have no positive or negative effect

294 TABLE I Recommended nutrient levels in diets for various categories of rabbits reared intensively Dietary composition (assuming a dry matter content of 89% )

Units

Digestible energy Metabolizable energy Fat Crude fibre Indigestible crude fibre Crude protein Amino acids Lysine Sulphur amino acids Tryptophan Threonine Leucine Isoleucine Valine Histidine Arginine Phenylalanine plus tyrosine Minerals Calcium Phosphorus Sodium Potassium Chloride Magnesium Sulphur Trace elements Iron Copper Zinc Manganese Cobalt Iodine Fluorine Vitamins A D E K

MJ k g - 1 MJ kg -~ % % % %

B1 (thiamine) B2 (riboflavine) Panthothenic acid B6 (pyridoxine) B12 Niacin Folic acid Biotin

Fattening

10.4 10.6 3 14 11 16

Lactation

10.9 10.4 3 12 10 18.0

Gestation

10.4 10.0 3 14 12 16.0

% % % % % % % % % %

0.65 0.60 0.13 0.55 1.05 0.60 0.70 0.35 0.90 1.20

0.90 0.60 0.15 0.70 1.25 0.70 0.85 0.43 0.80 1.40

-

% % % % % % %

0.50 0.30 0.30 0.60 0.30 0.03 0.04

1.10 0.70 0.30 0.90 0.30 0.04 -

0.80 0.50 0.30 0.90 0.30 0.04

ppm ppm ppm ppm ppm ppm ppm IU kg-~ IU k g - ~ ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm

50 5 50 8.5 0.1 0.2 0.5 6000 900 50 0 2 6 20 2 0.01 50 5 0.2

100 5 70 2.5 0.1 0.2 12 000 900 50 2

0

-

Maintenance

9.2 8.9 3 15-16 13 13.0

10.4 10.0 3 14 11 17.0 0.75 0.60 0.15 0.60 1.20 0.65 0.80 0.40 0.90 1.25

-

-

50

All purpose

0.40 0.30

50

70 2.5

2.5

0.2

0.2

12 000 900 50 2 0 0 0 0 0

600 900 50 0 0 0 0 0 0

0

0

1.10 0.70 0.30 0.90 0.30 0.04 0.04 100 5 7O 8.5 0.1 0.2 0.5 10 000 900 50 2 2 4

20 2 0.01 50 5 0.2

295 on the growth performances. Studies on fat-soluble vitamins are less numerous, and required dietary levels have been obtained empirically. An excessive level of Vitamin D (above 2300 IU kg-1 diet) is associated with renal and aortic calcification and, therefore, a level of 2000 IU k g - 1 diet should never be exceeded. Harmful effects, mainly poor reproduction of the does and a high proportion of kits with hydrocephalus at birth have been described after addition of extra Vitamin A to the drinking water ( Cheeke, 1985 ). The growing rabbit is more tolerant than the breeding doe to vitamin excess.

Recommended nutrient levels Recommendations to cover the requirements are usually given in terms of dietary levels in the complete ration, as shown in Table I (I.N.R.A., 1984). Significant deviation from the recommended dietary level may have consequences on the performance and the health of the animals. This concerns above all the lack of bulk in the diet. However, increasing indigestible crude fibre above 12% worsens the feed-conversion ratio. Energy value of the feed below 9.2 M J DE kg-1 results in poor performance owing to limited intake capacity, although no change in health status of the animal will occur. With high-lucerne diets and coarse grinding, fatal compaction of the caecum content was observed (Auvergne et al., 1987). Table II shows the variations in performance to be expected if the levels of dietary protein or of certain essential amino acids are lower than those recommended in Table I. Lower performance levels need not necessarily be economically undesirable as long as dietary protein levels do not fall below 12-13%. TABLE II Consequences of a reduction in recommended dietary levels of protein by 1% or certain amino acids by 0.1% on the performance of fattening rabbits (4-12 weeks) Nutrient under consideration

Crude protein Methionine Lysine Arginine

Reduction of dietary level

1% 0.1% 0.1% 0.1%

Reduction in d a i l y liveweightg a i n

Increasein food conversion ratio

Absolute amounts (gday -1)

%

Absolute %

-3 -2 -5 -1.5

-8.5 -6 -14 -4.5

+0.1 +0.1 +0.1 +0.1

+3 +3 +3 +3

Dietary level belowwhich these relationships will not hold 12 0.4 0.4 0.5

296 PRACTICAL FEEDING

Under controlled conditions of rearing, dried and ground raw materials are used for rabbits and this allows formulation of balanced compound diets. Rabbits do not tolerate dust and therefore it is preferable to use pelleted diets. The ideal pellet size lies between 3- and 4-mm diameter and 8-10-mm length. It is important never to go beyond 5-mm diameter to avoid wastage (Table III). Intake of pellets is enhanced compared with the intake of meal, resulting in higher LWG and improved feed-conversion ratio (Table IV). If only meal is available for feeding rabbits it may be advisable to mix it with TABLE III Influence of pellet size on the performance of growing-finishingrabbits (5-12 weeks) Pellet diameter (mm)

Daily feed intake (g) Daily liveweight gain (g) Food-conversion ratio

2.5

5

7

117 32.4 3.7

122 33.7 3.7

131a 32.0 4.4

aThe apparent increase in food consumption was caused by feed wastage. TABLE IV The effect of form of presentation of feed on the performance of young growing rabbits Reference

Form of presentation

Daily feed intake (gDM)

Daily liveweight gain (g)

Feed-conversion ratio (g DM g- 1 LWG )

Lebas (1973b) a

Meal Pellet Meal Pellet Meal Mash (40% water) Pellet

82 94 79 85 102 78 104

29.7 36.0 20.7 22.9 26.5 27.9 33.1

2.76 2.61 3.82 3.71 3.85 2.80 3.14

King (1974) b Machin et al. (1980) c

Formulation of diets aMaize 55.8%, soya bean meal 25%, barley straw 15%, DL-methionine 0.2%, minerals/vitamins 4%. bFish meal 10%, grass meal 20%, wheat bran 40%, oats 12.5%, wheatings 17.5%, molasses at 1.5% was then added to pellets. CBarley 62%, soya bean meal 17.5%, barley straw 12.8%, molasses 5%, lysine 0.25%, methionine 0.05 %, minerals 0.93%. The trial was carried out at 25 ° C.

297

water at a ratio of 60-40%, but feeders must be kept scrupulously clean. Automatic valve-controlled watering systems are always preferable. For a rapid reproductive rate, all rabbits, with the exception of males, are fed on an ad libitum basis. If the rate is less intense, does are to be fed on a restricted basis from weaning to the end of the following pregnancy. The recommended level of feeding is usually 30-35 g of DM kg -1 body weight per day. Young growing rabbits are invariably fed on an ad libitum basis. When they are group fed, a single watering point is sufficient for 10-15 individuals. One feeder is sufficient for 10 individuals although two are often used to reduce any problems that may occur if one of them is blocked. The following daily feed intake per animal, kept in groups, is considered to be adequate for high performance: (1) young growing (4-12 weeks), 110-130 g; (2) lactating does with their litter (weaning at 4 weeks), 350-380 g; (3) adult at maintenance, 120 g; (4) 1-1.4 kg per doe, including offspring.

REFERENCES Adamson, I. and Fisher, H., 1973. Amino acid requirement of the growing rabbit: an estimate of quantitative needs. J. Nutrition (London), 103:1306-1310. Auvergne, A., Bouyssous, Th., Pairet, M., Ruckebusch, Y. and Candau, M., 1987. Nature de l'aliment, finesse de mouture et donn~es anatomo-fonctionnelles du tube digestif proximal du lapin. Reprod. Nutr. Dev., 27: 755-768. Axelsson, J., 1942. Digestive capacity of hens and rabbits. Arch. Kleintierzucht., 3: 81-97. Battaglini, M. and Grandi, A., 1984. Stima del valore nutritivo dei mangimi composti per conigli. 3rd World Rabbit Congress, Rome, Vol. 1, Associazone Nazionale Coniglicultori Italiani, pp. 252-264. Berchiche, M., 1985. Valorisation des prot$ines de la fSverole par le lapin en croissance. Th~se doctorat I.N.P. Toulouse, pp. 137. Cheeke, P.R., 1985. Vitamins, swallowing an unnecessary pill, or vitamins make strange bedfellows. J. Appl. Rabbit Res., 8: 101-103. Cheeke, P.R., Bronson, J., Robinson, K.L. and Patton, N.M., 1985. Availability of calcium, phosphorus and magnesium in rabbit feeds and mineral supplements. J. Appl. Rabbit Res., 8: 72-74. Coates, M.E., Gregory, M.E. and Thompson, S.Y., 1964. The composition of rabbit's milk. Br. J. Nutr., 18: 583-586. Cowie, A.T., 1969. Variations in the yield and composition of the milk during lactation in the rabbit and the galactopoietic effect of prolactin. J. Endocrinol., 44: 437-450. De Bias, C. and Santoma, G., 1984. Valor nutritivo de los alimentos. In: C. De Bias Beorlegui (Editor), Alimentaci6n del Conejo. Mundi Prensa, Madrid, pp. 59-66. I.N.R.A., 1984. L'alimentation des animaux monogastriques: porc, lapin, volailles. I.N.R.A., Paris, 282 p. Jentsch, W., Schiemann, R., Hoffmann, L. and Nehring, K., 1963. Die energetische Yerwertung der Futterstoffe, 2. Mitteilung: Die energetische Verwertung der Kraftfutterstoffe durch Kaninchen. Arch. Tierernaehr., 13: 133-145. Jeroch, H., 1986. Ftitterung des Kaninchen. In: H. Jeroch (Editor), Vademekum der Fiitterung. VEB G. Fischer Verl., Jena, 632 pp. King, J.O.L., 1974. The effects of pelleting rations with or without an antibiotic on the growth rate of rabbits. Vet. Rec., 94: 586-588.

298 Lang, J., 1981. The nutrition of the commercial rabbit. Part 1. Physiology, digestibility and nutrient requirements. Nutr. Abstr. Rev., 51: 197-225. Lebas, F., 1971. Composition chimique du lait de lapine. Evolution an cours de la traite et en fonction du stade de lactation. Ann. Zootech., 20: 185-191. Lebas, F., 1973a. Variations des r~serves corporelles de la lapine au cours d'un cycle de reproduction. In: I.T.A.V.I. (Editor), Journ~es de la Recherche Avicole et Cunicole, D~cembre 1973, Paris, pp. 59-61. Lebas, F., 1973b. Poseibilit~s d'alimentation du lapin en croissance avec des r~gimes pr~sent~s sous forme de farine. Ann. Zootech., 22: 249-251. Lebas, F., 1979. Efficacit~ de la digestion chez le lapin adulte. Effets du niveau d'alimentation et du stade de gestation. Ann. Biol. Anim. Biochem. Biophys., 19: 969-973. Lebas, F., 1983. Bases physiologiques du besoin prot~ique des lapins.Analyse critiquedes recommandations. Cuni-Sciences, 1: 16-27. Lebas, F. and Jouglar, J.Y., 1984. Apports alimentaires de calcium et de phosphore chez la lapine reproductrice. 3rd World Rabbit Congress, Rome VoL I, 461-466. Lebas, F. and Franck, T., 1986. Incidence du broyage sur la digestibilit~de quatre aliments chez le lapin.Reprod. Nutr. Ddv., 26: 235-236. Lebas, F.,Maitre, I.,Seroux, M. and Franck, T., 1986. Influence du broyage des mati~res premieres avant l'agglomdration de 2 aliments pour lapins,diff~rantpar leur taux de constituants membranaires:digestibilit~et performances de croissance.4e Journ~es Recherche Cunicole en France, Paris Ddc. 1986, Communication No. 9. Machin, D.H., Butcher, C., Owen, E., Bryant, M. and Owen, J.E., 1980. The effectsof dietary metabolizable energy concentration and physical form of the dieton the performances of growing rabbits. Second World Rabbit Congress, Barcelona, Vol. 2, 65-75. Maertens, L. and De Groote, G., 1986. The influence of the crude protein and lysine content in the diet of the breeding results of does. 3rd International Colloquy, The Rabbit as a Model Animal and a Breeding Object, Rostock, 11-13 September, 1986, Section If,pp. 90-97. Maertens, L., Huyghebaert, G. and De Groote, G., 1985. Digestibilityand digestibleenergy content of various fats for growing rabbits.Cuni-Sciences, 3: 7-14. Nehring, K., Hofmann, L., Schiemann, R. and Jentsch, W., 1963. Die energetische Verwertung der Futterstoffe.3. Die energetische Verwertung der Kraftfutterstoffedutch Schweine. Arch. Tierern~ihr.,13: 147-161. Nelson, T.S.,Daniels, L.B., Shriver,L.A. and Kirby, L.K., 1985. Hydrolysis of phytate phosphorus by young rabbits.Arkansas Farm Res., 34 (4): p.8. Pagano-Toscano, G., Benatti, G. and Zoccarato, I., 1985. Digeribilithdegli alimenti per conigli: confronto dei metodi Weende e Van Soest per la stima della frazione fibrosa.Coniglicoltura, 21 (1): 37-42. Pairet, M., Bouyssou, Th., Auvergne, A., Candau, M. and Ruckebusch, Y., 1986. Stimulation physicochimique d'origine alimentaire et motricit~ digestive chez le lapin. Reprod. Nutr. DSv., 26: 85-95. Parigi-Bini, R. and Xiccato, G., 1986. Utilizzazione dell'energia e della proteina digeribile nel coniglio in accrescimento. Coniglicoltura, 23 (4): 54-56. Proto, V., 1980. Alimentazione del coniglio da came. Coniglicoltura, 17(7): 17-32. Proto, V., Gioffr~, F., Di Franca, A. and Maiolino, A., 1987. L'utilizzazione di alcune fonti di azoto non proteico (NPN) neUa nutrizione del coniglio con ciecotrofia. Coniglicoltura, 24 (3): 45-51. Prud'hon, M., ChSrubin, M., Goussopoulos, J. and Caries, Y., 1975. Evolution, au cours de la croissance, des caract~ristiques de la consommation d'aliments solide et liquide du lapin domestique nourri ad libitum. Ann. Zootech., 24: 289-298. Schiirch, A., 1949. Die theoretischen Grundlagen der KaninchenfUtterung. Schweiz. Landwirtsch. Monatsch., 17 (2) : 3-27. Teleki, J., Szegedi, B. and Juhasz, B., 1983. Effect of feed mixtures and urea supplementation on the protein metabolism of angora rabbits. Allattenyesz. Takarman., 32: 165-169.

Livestock Production Science, 19 (1988) 299-354 Elsevier SciencePublishersB.V., Amsterdam-- Printed in The Netherlands

299

III. 4. Pigs and Poultry Y. HENRY, H. VOGTand P.E. ZOIOPOULOS

INTRODUCTION During the last decades there have been significant changes in the allocation of feed resources to pigs and poultry. Meat or egg production from non-ruminants is mainly based on the use of concentrates, with recent steady trends to a more diversified and economical feed supply, in order to lower the cost of production. This has resulted in the development of alternative feeds to cereals and common oil meals, with great fluctuations in composition and nutritive value, and t~ the use of industrial by-products and new processed feeds as energy and/or protein sources. Within this wide range of feeds, more fibrous feeds are being used, especially for pigs. Owing to the negative effect of fibre components on the availability of dietary nutrients (energy as well as protein and amino acids) there is an increasing need for a precise evaluation of the nutritive value of feedstuffs and of compound feeds. In order to meet the constraints of increasing productivity, there has been a trend to select and raise animals with a high level of performance for lean meat and egg production. More emphasis is then placed on protein and essential amino acids, to be supplied in greater amounts and in a more available form according to energy intake. The energy supply may nevertheless become critical through a limitation of voluntary feed intake for fast growing, lean animals. This is a problem of increasing relevance both for pigs and for chickens, especially in the case of excessive diet bulkiness (high fibrous feeds), owing to a limitation caused by physical factors related to gut fill. Similar limitations may occur when unpalatable substances, frequently associated with fibre, are present in the diet, as well as toxic and antinutritional substances. Therefore, the use of feed resources in non-ruminants implies a clear understanding of feed evaluation and nutrient requirements. This includes energy and protein as the major components of feeds, and it will be assumed that the other nutrients, i.e., minerals and vitamins, are not the limiting factors in the diet. Three parts will be considered: (1) nutritive value of feeds; (2) nutrient requirements; (3) future developments in the assessment of feed evaluation and nutrient requirements. The present situation of the systems in use in the European countries will be described in the Appendix. 0301-6226/88/$03.50

© 1988ElsevierSciencePublishers B.V.

300 NUTRITIVE VALUE OF FEEDS

Feed evaluation for non-ruminants is mainly based on the assessment of energy and protein (with essential amino acids), which are the 2 major quantitative components of the diet. However, a wide range of other nutrients are present, including minerals, trace elements and vitamins, although these are in low or minute amounts, and are generally provided in feed formulation at a relatively low cost.

Energy Former systems Until the 1960s energy evaluation of feeds in most European countries was based on the findings of Kellner (1913) on net energy for fat formation in fattening beef cattle. This resulted in the starch equivalent (SE) which was subsequently converted to fodder unit (FU) systems, usually equivalent to the energy value of 1 kg of barley. This concept was applied to pigs in the Scandinavian countries as the Scandinavian fodder unit (SFU), with appropriate adaptations to the digestibility coefficients. At the same time the total digestible nutrients (TDN) system, which corresponds to the total amount of digestible nutrients on an equicaloric basis, was developed and applied in some countries: as T D N in the U.K. (Evans, 1948); as "Gesammtn~ihrstofff' or GN in Germany (Lehmann, 1924). In France, a net energy system was derived by Leroy (1949), based on the calculation of metabolizable energy ( ME ) from TDN, its correction to net energy (NE) and conversion to a feed unit ("Unit~ Fourrag~re" or UF) equivalent to the energy value of 1 kg of barley. Since these systems were established from research data obtained on ruminants, there was a need to reconsider a specific energy evaluation procedure for pigs. This became possible with the development of direct calorimetric measurements of digestible energy (DE), metabolizable energy (ME) and net energy ( NE ) for fattening ( Schiemann et al., 1971 ) and growth ( Just, 1982a). In the case of poultry T D N (or GN; Lehmann, 1924) was also used in a first stage for the evaluation of feeds along with SE, SFU or total feeding value. In the 1950s "productive energy" values (Fraps and Carlyle, 1939, 1942) were the primary measures of energy value of poultry feedstuffs. Since the second half of the 1950s (Carpenter and Clegg, 1956; Hill, 1957; after the first proposal of Axelsson, 1939) there has been a general agreement on the use of metabolizable energy in the evaluation of poultry feedstuffs. A net energy system for fat formation is only used in some East European countries (Schiemann et al., 1971 ). Similarly, a method for calculating the net energy content of feedstuffs from determined ME values was described by de Groote (1974a).

301

Present systems for the energy evaluation of feeds for pigs and poultry Feed energy value for non-ruminants is expressed in any of the 3 main systems: DE, ME and NE. It is measured directly from calorimetric determinations (kJ or kcal), in the case of DE or ME, or more generally based on regression equations derived from digestible nutrients in the Weende analytical system (digestible crude protein, DXP; digestible fat, DXL; digestible crude fibre, DXF; digestible nitrogen free extract, DXX) or simply from crude nutrients (crude protein, XP; fat, XL; crude fibre, XF; nitrogen free extract, XX, or XP, XL; starch, S; sugar, Z). In this respect, a distinction is to be made between single feedstuffs and compound feeds, for which the ingredient composition may be unknown, so that the prediction of energy value is restricted to data on the crude chemical composition. The energy systems for non-ruminants have been presented in detail in several reviews; among these the most recent, for pigs, are from Henry and Pdrez (1982, 1983), Just (1982a), Morgan and Whittemore (1982), and, for poultry, from Farrell (1979), Fisher (1982) and Hartfiel (1983). A brief description of DE, ME and NE systems will be given, by considering for each of them the methods of measurement, the factors of variation (animal and dietary effects, level of feeding) and the mode of calculation. DE and ME systems. The DE value of feeds for pigs is simply measured in digestibility trials by total collection of faeces or by using feed markers along with faecal sampling. Digestibility trials with chickens are complicated by the voiding of mixed excrement (urine and faeces). An appropriate technique is to operate on chickens in order to form an artificial anus, whereby the faeces may be collected separately from the urine. Another technique is to determine the amount of uric acid in the mixed excrement and to calculate the total urinary nitrogen. As a consequence of these difficulties, DE values are not generally employed in poultry-feed formulation. The accurate measurement of ME requires methane losses to be taken into account in addition to urine, and this is only possible in a respiration chamber. In fact, losses of energy through methane in pigs are very low, especially in growing animals: they usually represent less than 0.5% of gross energy ( GE ), according to recent literature (Henry and Noblet, 1986). They are even lower in poultry. Although methane losses are likely to be higher in older animals, especially with diets containing a high level of fermentable carbohydrates, in practical conditions this source of energy loss is neglected, so that ME is simply determined by subtracting from DE the energy loss in urine. The urinary energy loss, mostly in the form of nitrogen, is closely dependent on the dietary protein level, and especially the amino acid balance (i.e. the level of the limiting essential amino acid). Therefore, for ME determination, it is necessary to standardize the level of nitrogen retention, for optimum pro-

302 tein utilization, for a given level of nitrogen retention, or for zero nitrogen balance. In pigs, ME is preferably measured under conditions of optimum protein and amino acid balance, in order to obtain a nitrogen retention of 0.50 or more according to apparently digested nitrogen in growing animals. With balanced diets ME represents a rather fixed proportion of DE: around 0.95. But in single feedstuffs ME: DE ratio is inversely related to protein level. In poultry, it is a common practice to correct ME data on the basis of nitrogen equilibrium (MEn), i.e., zero nitrogen retention (subtracting 8.22 kcal or 34.4 kJ per g of uric acid nitrogen), to correct for differences in nitrogen retention of the birds to which it is fed. Through these corrections for N-balance, protein-rich feedstuffs are underestimated and, on the other hand, energy yielding feedstuffs are overestimated. Therefore a correction on the basis of 0.33 of retained from digested nitrogen or 0.25 of retained from ingested nitrogen would be more realistic (Hartfiel, 1964; Hartfiel et al., 1970). The method in general use for measuring ME in feed ingredients with growing chicks was initiated at Cornell University in the 1950s (Hill and Anderson, 1958). ME measurements are also made with laying hens (to have birds with 0.33 digestible N retention), or with adult cocks (to have birds with no N gain or N loss). Farrell (1978) developed a rapid method for measuring a noncorrected apparent ME value with trained roosters. ME in poultry is expressed in apparent (AME) or true ( T M E ) value, by considering the endogenous losses of energy; AME in poultry is similar to ME in other animals and chapters. A rapid method for measuring T M E was developed by Sibbald (1976), using force-fed adult cockerels with a fixed amount of feed. T M E for poultry is the GE of the feed minus the GE of the excreta of food origin, i.e., a correction is made for endogenous energy. Because of the difficulty of its measurement the T M E method has not been adopted in the European countries. A new joint assay for the determination of AME and T M E was recommended by McNab and Fisher (1984). A new ME system for pigs based on negative corrections for the energy value of fermentable substances has been developed in the F.R.G. and is used as an energy unit (MJ) for expressing dietary recommendations (D.L.G., 1984). Animal effects, such as age, sex and genotype, have generally a small effect on DE or ME. In pigs, there is, however, some trend towards a slightly higher value with increasing age, probably owing to a better ability to digest fibre. This explains why DE and ME determinations with growing pigs are usually made within the liveweight range of 30-60 kg. DE and ME values in pigs are slightly decreased at a high level of feeding close to ad libitum. They depend, however, mainly on diet composition and especially on the fibre content, which exerts a linear depressive effect on total energy utilization at a rate which varies according to type of fibrous component. It is therefore a good predictor of the digestibility of energy (Henry, 1976; Pdrez et al., 1984). Conversely, in

303 poultry, dietary fibre may be considered as an inert diluent with no value for the birds ( Carr~ et al., 1984). Tables of the DE and ME values of feeds for pigs and poultry in the different countries are usually based on direct calorimetric measurements. In pigs, the experimentally determined DE values, which refer to a known feed composition, may be corrected for variable fibre content, within a given homogeneous class of feedstuffs for fibre composition, as suggested by Henry and P~rez (1982, 1983). Also in pigs, very few data on direct ME values of feeds are available, in the absence of well-defined experimental conditions with balanced diets for essential amino acids. Therefore, it has been suggested (I.N.R.A., 1984) that the directly measured DE values should be converted to ME, after taking into account an estimate of energy losses in urine for an optimum protein retention and in the form of methane. An alternative indirect approach may be used to predict DE and ME from digestible nutrients, according to the Weende proximate analysis. But, by doing so, the digestibility coefficients for the dietary nutrients are assumed as being constant irrespective of fibre level. Interactions between digestibility coefficients and fibre level are likely to occur in pigs, so that DE is determined more accurately from direct experimental values corrected for fibre content. On the other hand, the use of crude nutrients in the prediction equations only applies to a control of the energy value of compound feeds. Some equations are available for pigs as well as for poultry, as shown in the Appendix. For the calculation of ME value of single feedstuffs in poultry Janssen and Terpstra (1972) used formulae or correction factors for differences in the nutrient content of feedstuffs: a new common European Energy Table is now calculated on this basis (W.P.S.A., 1986).

The efficiency of M E utilization. The energy losses as extra heat during the transformation of ME to maintenance and animal products are based on the measurement of heat production or energy deposited from indirect calorimetry or on the comparative slaughter technique. They are both associated with the type of production ( animal effects) and with the chemical composition of the digested nutrients (dietary effects). (a) Type of production effects. ME is more efficiently converted by pigs for fat formation ( kf= O.74 ) than for protein deposition (/% = 0.56 ) (A.R.C., 1981 ). Similar values are reported for poultry (de Groote, 1974b): 0.70 to 0.84 for lipid deposition in adult birds and 0.37 to 0.84 in growing chicks; about 0.50 for protein deposition. The estimated efficiency of ME utilization for maintenance is 0.80 in pigs and 0.85 in poultry (adult cockerels, growing chicks and laying hens). It follows that the efficiency of ME utilization for growth (kg) is inversely related to the proportion of energy retained as protein. Therefore, the leaner the animal, the lower the value of/% which lies generally between 0.65 and 0.75

304 in growing pigs. In common practice, there is little fluctuation of ME utilization for growth (around 0.70) with varying energy partitioning for lean and fat 0.70-0.75. A similar range of efficiency (0.65-0.70) is noted for energy deposition in maternal and foetal tissues in the gestating sow, but the efficiency for foetal growth alone is much lower: 0.50 (Noblet and Etienne, 1986a,b,c ). In the lactating sow, the efficiency of conversion to milk secretion is between 0.70 and 0.75 (Noblet and Etienne, 1987a,c,d). In laying hens, ME is used with 0.60 efficiency for egg production and 0.80 for body energy gain ( de Groote, 1974b). (b) Plane of nutrition effects. According to the differential efficiencies of ME utilization for maintenance and types of production, the overall NE value of the diet is influenced by the level of feeding (ME/MEre) or the animal production level ( APL = ( NEro + NEg)/NE~ ). To obtain a single NE value for growing animals, it is therefore necessary to choose a given level of feeding, preferably close to ad libitum in high-performing pigs, as suggested by the Dutch workers (van der Honing et al., 1984). (c) Dietary effects. ME utilization is affected by the chemical composition of the absorbed nutrients to a greater or lesser extent depending on the type of production. ME from dietary fat is used efficiently by pigs for fat deposition: the corresponding efficiency is 0.90 compared to 0.73, 0.63 and 0.50 for digested nitrogen-free extract, crude fibre and crude protein, respectively, according to Schiemann et al. (1971). The superiority of fat over carbohydrates for energy deposition in growing pigs is well established. Similarly, in growing chicks, the efficiency values from carbohydrates and fat for lipid deposition are 0.75 and 0.84, respectively. On the other hand, the efficiency of utilization of ME from the digested fibrous substances is relatively low: about 0.60 of that corresponding to starch in pigs. It follows that the efficiency of ME utilization is negatively correlated with fibre content in the diet (Just et al., 1983a). Net energy systems. (a) NEF system. During the 1960s, following the original work of Kellner (1913), the research group of the Oskar Kellner Institute in Rostock (G.D.R.) proposed a new system based on the measurement of net energy for fat formation (NEF) in heavy castrated male pigs between 90 and 175 kg liveweight (NEFs) or adult cocks (NEFh), depositing a predominant proportion of fat in their body gain. After regression of retained energy on the amounts of digestible nutrients according to the Weende fractionation system, and the metabolic liveweight (W°75), to take into account the maintenance requirement, a prediction equation for NEF was derived (Schiemann et al., 1971; Hoffmann and Schiemann, 1980)

Pigs: N E F (kJ kg -1) =10.70 DXP+35.70 DXL+12.37 ( D X F + D X X ) ; Poultry: NEFh (kJ kg -1) =10.80 DXP+33.45 DXL+13.35 ( D X F + D X X ) , with digestible nutrients in g kg-1.

305 The main characteristic of this system is to provide a discrimination in the utilization of ME according to the type of nutrient, with the relative efficiencies of 1.0, 1.34 and 0.71 for digested carbohydrates, fat and protein, respectively. But it does not take into account the differential effects due to maintenance, type of production and differences in the level of feeding. (b) Danish net energy system for growth of pigs. In Denmark Just (1970) reported that energy concentration (ME kg-1 DM) accounted for the major part (90%) of the differences in net energy value (maintenance + growth) measured in growing pigs between 20 and 90 kg liveweight. A practical net energy system was then proposed (Just, 1975, 1982a), based on ME adjusted for differences in energy concentration, according to the following equation: N E (MJ kg -1 D M ) = 0 . 7 5 M E (MJ kg -~ D M ) - 1 . 8 8 ,

with ME being estimated from the contents of digestible nutrients (g kgDM) M E (MJ kg -~ D M ) =0.0215 D X P + O.0377 D X L + O.O173 ( D X F + D X X ) .

The net energy of 1 kg common barley (7.72 MJ kg -~ ) was defined as a feed unit (FE~). The constant term (1.88 MJ) in the prediction equation of NE indicates that for a given NE value feedstuffs with a high energy concentration, for instance containing a high amount of starch, are relatively better evaluated for production value than those containing a high proportion of fibre. On the other hand, no discrimination is made according to the type of nutrient, i.e., between ME from fat, protein and carbohydrates. Prediction of energy value in compound feeds For research or advisory purposes the energy value of diets can be estimated either from direct calorimetric measurements or with the aid of prediction equations based on digestible nutrients. In the control of compound feedingstuffs, however, when the actual composition of the feed mixtures is not known, prediction equations should essentially be based on chemical criteria. These include gross composition parameters or some fibrous components which take into account changes in energy digestibility in pigs, while in poultry the cell wall fraction is practically indigestible and may be considered as a diluting factor of the energy value (Carrd et al., 1984). Several regression equations based on chemical analyses have been suggested for the control of compound feeds, among which the most recent ones, expressed in DE or ME, are reported in the Appendix. Obviously, the error for predicting the energy value from crude nutrients is much higher than from digestible nutrients: according to Just et al. (1984), the corresponding coefficients of variation for pig diets were 5.0 and 0.8%, respectively, in the case of ME measurements. Therefore, these equations are only valid as a control of

306 the energy value of compound feeds within rather wide limits: the expected accuracy of predicted energy values from crude chemical composition is discussed in detail in the reviews of Fisher (1982) and Alderman (1985) for poultry and for pigs, respectively. In the U.K. (Morgan et al., 1987) and France ( Pdrez et al., 1984) the best predictors of DE or ME in mixed feeds were GE and neutral detergent fibre (NDF) as determined by Van Soest's procedure (Van Soest, 1963; Van Soest and Wine, 1967) ; this method of prediction was significantly better than that obtained from classical proximate composition including only crude fibre. Nevertheless, both effectiveness and precision of analytical techniques should be taken into consideration for choosing the most appropriate prediction equation. Within the E.E.C. committee of experts on "Straight and compound feeds", there has been an attempt since 1980 to establish a harmonized method for the calculation of the energy value of compound feeds. The working group for pigs, using pooled data from various trials in E.E.C. countries and Switzerland, proposed a prediction equation for consideration (see Appendix). For evaluation purposes in trade a minimum tolerance of 0.5 MJ was proposed. In poultry, the first equation based on crude nutrients was developed by Carpenter and Clegg (1956). Recently, in 1985, the Working Group of the European branches of W.P.S.A. proposed a new formula which has also been accepted by the E.E.C. for a control of the energy value in poultry feeds (see Appendix).

Comparison of energy values from different systems and conversion between units for pigs Since in poultry feed energy value is almost universally expressed in ME units, this problem only applies to pigs. Four different energy systems are used in practical pig feeding in European countries: DE, ME, which may be corrected for fermentable substances, NEF and Danish NE for growth. For the comparison of the available systems, two steps need to be considered, whether the comparison refers to single feeds or to least-cost formulated diets, in relation to production potential. The comparison of the energy value of single feeds in the different systems is given in Table I. The relative energy values are expressed in percentage of barley as a reference (and maize in the case of poultry). According to the way it is defined, DE does not provide any indication of the real energy value of the absorbed nutrients. Thus, it overestimates proteinrich feeds, and fibrous feeds to some extent, while the value of fat is underestimated. Similar shortcomings are found in ME except that it allows a better evaluation of protein-rich feedstuffs. As expected, correcting ME for bacterial fermentable substances (MEc.BFs) provides a lower relative value for highfibre feedstuffs. Among the NE systems, NEF provides a better evaluation of fat but an

1 2 . 5 8 12.60 9.84 8.90 1 0 . 2 6 10.26 I0.58 9.14 9.40 8.78 1 1 . 9 3 10.09 8.69 7.82 7.69 6.10

12.58 10.24 10.87 I0.58 9.61 12.12 9.28 7.90

13.55 12.44 15.67 10.80 14.29 13.71 32.72

13.63 13.04 16.49 9.70 13.61 13.50 31.35

14.34 13.79 17.56 11.16 15.47 14.00 31.35

12.28 13.74 13.53 11.05 13.51 10.60 9.35

ME3BFs (MJ)

12.27 13.86 13.42 11.08 13.52 11.00 7.73

ME ~ (MJ)

12.62 14.21 13.84 11.41 14.92 11.90 8.50

DE 2 (MJ)

Pigs

Energy value

9.23 6.93 7.52 6.91 8.97 9.19 6.66 5.84

9.09 8.27 11.40 6.01 8.09 9.75 31.32

8.77 9.92 9.50 8.08 8.58 7.10 6.13

NEF (MJ)

8.11 5.87 6.72 6.18 7.95 7.95 5.79 4.55

8.80 8.03 10.50 7.02 9.19 9.34 22.85

7.87 8.88 8.72 6.79 9.26 7.03 5.79

Danish NE (MJ)

5.13

11.05 10.22 15.19 9.97 II.83 8.36 29.30 37.65 11.44 6.86 7.70 8.39 -

11.92 13.95 12.98 10.82 9.33 5.90 6.51 lll.l 106.3 143.1 91.0 126.1 114.1 255.5

100 113.0 109.4 90.3 110.2 95.9 68.1

ME

99.7 102.5 81.1 8 3 . 5 86.1 8 8 . 6 83.8 8 6 . 2 76.1 7 8 . 3 96.0 9 8 . 8 73.5 7 5 . 6 62.6 6 4 . 4

113.6 109.3 139.1 88.4 122.6 110.9 248.4

100 112.6 109.7 90.4 118.2 100.6 72.9

Poultry 2 DE ME (MJ)

102.6 72.5 83.6 76.9 71.5 82.2 63.7 49.7

II0.3 101.3 127.6 94.4 116.4 111.6 266.4

100 111.9 110.2 90.0 110.0 86.3 76.1

MEcn~s

111.8 102.0 133.4 89.2 I16.8 118.7 290.3

100 112.8 110.8 86.3 117.7 89.3 73.6

Danish NE

105.2 103.0 79.0 74.6 85.7 85.4 78.8 78.5 102.3 I01.0 104.8 101.0 75.9 73.6 66.6 57.8

103.6 94.3 130.0 68.5 92.2 111.2 357.1

100 ll3.1 108.3 92.1 97.8 81.0 69.9

NEF

Relative values: pigs (Barley: 100)

92.7 85.7 127.4 83.6 99.2 70.1 245.8 315.9 96.0 57.6 64.6 70.4 43.0 -

100 117.0 108.9 90.8 78.3 49.5 54.6

Barley:100

36.8

79.2 73.3 108.9 71.5 84.8 59.9 210.0 269.9 82.0 49.2 55.2 60.1

85.5 100 93.1 77.6 66.9 42.3 46.7

Maize:100

Relative values: poultry

~Tables of composition according to I.N.R.A. (1984) and digestibility coefficients for pigs from D.L.G. (1984). 2European Table of energy values for Poultry feedstuffs, Beekbergen (W.P.S.A., 1986). :*ME corrected for Bacterial Fermentable Substances (BFS), as calculated in D.L.G. tables (1984). MEcBFs, NEF and Danish NE values were calculated with digestible nutrients obtained from I.N.R.A. composition data and DLG digestibility coefficients for similar feedstuffs.

Barley Maize Wheat Oats Soyabean meal (48% XP) Rapeseed meal Sunflower seed meal (30% XP, 25% XF) Peas Field beans Soya bean whole seeds Meat meal (35% XP) Fish meal Whey powder Tallow Soya bean oil Cassava meal Wheat bran Maize gluten feed Sugar cane molasses Beet pulp Citrus pulp Lucerne meal Soya bean hulls

Feedstuffs

Energy value of various feedstuffs for pigs in different systems and in comparison with poultry (kg as fed) 1

TABLE I

z~

308

underestimation of the value of protein-rich feeds. Therefore, this system is in favour of the inclusion of fat in combination with various protein replacement sources and fibrous feedstuffs, and a lower proportion of cereals, thus resulting in an increased complexity of least-cost formulated diets. The relative energy values of protein feeds are comparable in Danish NE and ME systems; in addition, the Danish NE gives a better evaluation of high-energy feeds, such as cereals, but this is due to starch content as opposed to fat in the NEF system. The relative merits of the available energy systems in least-cost formulation of balanced diets, according to price situation and energy density, have been described in some recent publications (Borggreve et al., 1975; Brette et al., 1986). According to the system used, the energy values for feeds of known composition are defined by directly determined values (DE, ME) or by a set of digestibility coefficients which are used in a prediction equation (NEF, Danish NE ). For converting from one energy unit to another the digestible nutrients could serve as a common link. While ME in mixed feeds is a rather constant proportion of DE (around 0.95-0.96), in single feedstuffs the conversion of DE to ME requires the protein content or protein-energy ratio to be taken into account. The average ME value of 1 kg of barley (85% DM) for pigs amounts to 12 MJ. The average correspondence between T D N and DE was established by Asplund and Harris (1969) and from Crampton et al. (1957) as the following: I kg T D N = 18.43 MJ DE.

Protein Basis of system Protein evaluation of feedstuffs in non-ruminants requires two successive steps to be considered: (i) the amino acid composition of feed protein by reference to the requirements; (ii) the digestibility and more generally the availability of protein and amino acids (AA). This topic has been developed recently in detail in some main reviews: for pigs, Fuller (1980), R~rat (1981), Low (1982), Darcy and R~rat (1983), Tanksley and Knabe (1984), Henry (1985a), Sauer and Ozimek (1986); for poultry, Fisher (1983), Larbier and Leclercq (1983), Boorman and Burgess (1986).

Amino acid composition o/protein in feedstuffs Tables of amino acid composition of feeds have been established in different countries. An example of the amino acid composition of the main feedstuffs for non-ruminants is reported in Table II. The contents of essential amino acids are expressed either as amounts in g per kg feed (or % ) or as a percentage of total protein (i.e. 16 g N, using 6.25 conversion factor from N to crude protein). In fact, the percentage of a given amino acid in protein is not always constant, and may decrease as protein content increases, owing to changes in

100 90 113 100 480

492 295 352 220 264 370 646 561 150 210

860 860 860 860 880

910 900 890 860 870 890 920 930 870 900

17.0 10.7 19.7 16.0 16.6 23.5 50.4 29.5 5.6 6.9

3.7 2.5 3.2 4.0 30.5 11.8 12.6 17.3 5.9 5.3 11.5 23.9 12.9 5.0 9.7

4.2 3.9 4.7 5.0 14.3 13.3 10.6 15.7 8.7 9.3 14.4 27.3 18.0 5.4 8.3

3.4 3.2 3.4 3.5 18.8 4.9 3.8 4.3 2.0 2.2 4.8 6.5 2.9 2.4 1.6

1.1 0.6 1.3 1.2 6.5 3.45 3.6 5.6 7.3 6.3 6.35 7.8 5.25 3.7 3.3

3.7 2.8 2.8 4.0 6.35 2.4 4.3 4.9 2.7 2.0 3.1 3.7 2.3 3.3 4.6

4.2 4.3 4.15 5.0 3.0 2.7 3.6 4.45 3.95 3.5 3.9 4.2 3.2 3.6 3.95

3.4 3.55 3.0 3.5 3.9 1.0 1.3 1.2 0.9 0.8 1.3 1.0 0.5 1.6 0.75

1.1 0.65 1.15 1.2 1.35

Lysine a ÷ b XP Wheat 1.45 ÷ 0.173 XP Maize 1.31 ÷ 0.159 XP Barley 1.67 ÷ 0.234 XP Peas 3.64 ÷ 0.595 XP Field beans 5.3 ÷ 0.467 XP 2Reference: I.N.R.A. (1984). :~Faecal digestibility (CVB-Veevoedertabel, 1984 ). 4European table of energy values for poultry feedstuffs, Beekbergen (W.P.S.A., 1986).

0.90 0.78 0.79 0.88 0.81 0.85 0.90 0.82 0.67 0.80

0.78 0.81 0.87 0.79 0.89

Xp 2

Poultry

0.58

0.93 0.86

0.85

0.72 0.67 0.77 0.92

0.88 0.85 0.69 0.86 0.70 0.90 0.88 0.80 0.73 0.85

0.70 0.84 0.81 0.75 0.87

Lysine :* X p 4

Digestibility coefficients

Threonine Tryptophan Pigs

Amino acid content (g/16 gN )

DM Protein Lysine I Methionine+ Threonine Tryptophan Lysine Methionine+ cystine cystine

Composition (g kg- 1)

1Prediction equations of lysine content (g kg ~) from crude protein (XP) content (g kg- ~) (I.N.R.A., 1984) (expressed as g kg- 1DM).

Barley Maize Wheat Oats Soya bean meal (48% XP) Peanut meal Sunflower meal Rapeseed meal Peas Field beans Soya beanwhole seeds Fishmeal Meat meal Wheat bran Maize gluten feed

Feedstuffs

A m i n o a c i d c o m p o s i t i o n o f s o m e r e p r e s e n t a t i v e ~ e ~ t u f f s i n p i g a n d p o u l t r y ~eding

TABLEII

¢.D

310

the distribution of the component protein fractions. Prediction equations are thus available for estimating amino acid content in feed from protein content (I.N.R.A., 1984). The ultimate step in protein evaluation of individual feedstuffs or of complete balanced diets is to assess the hierarchy of the successive limiting amino acids by reference to the corresponding requirements of the animals, expressed as a percentage of the diet or in relation to energy supply. Among the essential amino acids, the most limiting for pigs is generally lysine, owing to its low content in cereals. The secondary limiting amino acids are threonine, tryptophan or methionine, in an order which depends on the pattern of feed supply in comparison with the requirements.

Availability of protein and amino acids The apparently digestible crude protein (DXP) as measured from total faecal collection is a fairly good indicator of the overall protein quality at the digestive level. However, there are some shortcomings in the significance of faecal or total digestibility, especially for amino acids, since the modification of nitrogen residues by microflora in the hind gut ( ammonia absorption, bacterial protein) were shown to have little or no nutritional value to the pig (Zebrowska, 1973 ). Following pioneering work with poultry ( Payne et al., 1968) it was suggested that the appropriate way for evaluating availability of amino acids was to measure their digestibility at the end of the small intestine (ileal digestibility), using pigs fitted with simple or re-entrant cannulas to the ileum, or ileo-colic postvalvular fistulas. The development of ileo-rectal anastomosis in pigs according to a technique developed recently (Laplace et al., 1985), enabling a total collection of ileal digesta, should be promising for measurements on a routine basis. In poultry, the problem of eliminating bacterial influence in the hind gut is less crucial than in pigs, although caecestomized birds are used along with intact animals for amino acid digestibility measurements. In both cases amino acid digestibilities are expressed in apparent or true values, after correcting for endogenous losses. An alternative approach for evaluating AA availability in feedstuffs is based on growth assays, especially with growing chickens but also with pigs (Major and Batterham, 1981; Sato et al., 1987). The digestibility of crude protein and amino acids may be influenced by various dietary factors, such as the source of protein itself, fibre content, technological treatments and antinutritional factors, and to a lesser extent by animal-related factors, i.e., age, liveweight (Zoiopoulos et al., 1983; Just, 1986). In pigs, faecal digestibility of amino acids is generally higher than ileal digestibility, but great fluctuations in the difference between the two sites are observed ( from 2 to 14 points for total nitrogen). Furthermore, the differences

311

according to diets and protein sources are better revealed by measuring digestibility at the terminal ileum. At the present time, extensive tables of AA availability for pigs based on ileal measurements are not yet available. Before obtaining more precise and complete data with this procedure, two attempts have been made for estimating AA availability in feedstuffs for pigs. -In The Netherlands, tables of the content of faecal digestible amino acids have been established for lysine, methionine and cystine in a wide range of feedstuffs ( C.V.B., 1984). -In Denmark, an approximation of AA digestibility was suggested by multiplying the AA contents of a given feedstuff by the apparent digestibility of total protein, assuming that there is an overall relationship between protein digestibility and that of the different essential amino acids. These data are included in the Danish Tables of feed composition (Andersen and Just, 1983; Just et al., 1983b). In poultry, the apparent digestibility of lysine and threonine in common diets is around 0.85, compared with 0.80 for cystine and 0.90 for the other amino acids. In The Netherlands, in the booklet "Feeding values for poultry" (Janssen et al., 1979 ), tables of apparent digestibility values for 18 amino acids have been published and are often used in practice. NUTRIENT REQUIREMENTS

General remarks

Through increasing intensification there has been a trend toward more standardization in poultry and pig production with respect to genotypes, feeding regime, housing and environmental conditions, and marketing procedure. Nevertheless, large differences still exist between the European countries in the kind of production. This is especially the case for pigs, which are produced within a wide range of weight at slaughter: from light porkers (60 kg liveweight) in the U.K. to heavy pigs (145-160 kg) in Italy, through baconers in Denmark (90 kg), with the most common slaughter weight ranging between 100 and 110 kg. In poultry there is more uniformity in the type of broiler produced for meat, but, in addition, the increased contribution of secondary avian species brings a great variability in meat supply. Different ways are used to express nutrient requirements, either in amounts per day at a given liveweight and for a known level of productivity (litter size, egg production, liveweight and tissue gain), or as percentages of a diet of a standard energy value within a given liveweight interval. In fact, there is a lack of uniformity in the presentation of the requirements among the European countries, whether one considers production objectives (carcass weight and composition), the level of feeding (whether the animals are fed to appetite or

312

restricted), the categories of animals within the life cycle in connection with husbandry practices, or nutrient availability (protein and amino acids) in experimental diets. This makes it difficult to compare the requirements in the various countries on a common basis. The nutrient requirements of non-ruminants are essentially based on the results of feeding trials, taking into account appropriate criteria related to production objectives. In each country, they are derived from a wide range of data, not simply research data from the home country or region, but also from world literature. In addition, the factorial approach is being developed as more information is available on nutrient outputs and their rates of utilization for maintenance and production, but is not yet fully adequate for predicting the requirements with sufficient precision and reliability, except for minerals ( calcium, phosphorus) and to a limited extent for energy. Only recently new data have been collected which provide quantitative changes in energy deposition and its partition into protein and fat in relation to growth potential and composition of gain. In this respect significant progress has been made for nutrient recommendations for pigs in some countries, as in the U.K. (A.R.C., 1981), the G.D.R. and the F.R.G. (D.L.G., 1984), towards a better understanding of the variations in recommended allowances with production conditions. In the same way, the factorial approach has been applied recently to poultry, in the U.K. (Fisher, 1983) and the F.R.G. (Vogt, 1987b).

Energy

Until now a common practice in most European countries has been to restrict feed energy below ad libitum level, both in growing animals (to improve carcass leanness further in addition to the selection of lean genotypes) and in breeding stock (to spare energy for producing weaning piglets at a lower cost, especially during periods of low requirements as in pregnancy). Feed or energy recommendations are thus usually given in daily amounts of feed of a known energy value according to liveweight. However, with the more extensive use of rapidly-growing lean animals, specifications are limited to energy concentration.

Dietary energy concentration. Pigs require a relatively high energy concentration in their diets, especially after weaning (14-14.5 MJ DE kg -1) (energy concentration data in DE may be converted to ME by multiplying by 0.95) and during the growing and finishing phase (13-14 MJ DE kg-1), in order adequately to meet their energy requirement for fast lean tissue growth and to express an optimum feed-conversion efficiency. With breeding sows the energy density may be lowered to 12.5 or 12 MJ DE kg -1 during pregnancy, owing to a low energy requirement above maintenance, while during lactation the high

313 level of energy requirement for milk secretion demands a higher concentration (13 MJ DE kg-1 or more). The usually recommended range of energy density in a given country also depends on the energy value of the most common feed resources: for instance, in Northern Europe where barley is extensively used the standard energy concentration is kept down to 12.5 MJ DE or 12 MJ ME kg -1. Expressed in barley equivalent (12.5 MJ DE kg-1), the relative values of feed density are 1.12-1.16 in weaned piglets, decreasing to 1.04-1.12 in growing-finishing pigs, 1.0-1.04 and 0.96-1.0 in lactating and pregnant sows, respectively. When pigs are fed to appetite the optimum energy concentration for producing carcasses without excessive fatness depends on tissue growth characteristics. With conventional pigs exhibiting a high propensity to fatten the energy density should be restricted to keep carcass adiposity within acceptable limits (12.5 to 13 MJ DE kg-1), while lean-type animals are able to convert highly-concentrated feeds without adverse effect on carcass quality ( Henry, 1985b).

Amount of feed. The amount of feed or energy required by the pig according to the physiological status (growth, pregnancy, lactation) may be predicted in a first approximation by the factorial method from the components of energy requirements for maintenance and production, and from the rates of utilization of energy (ME) for each type of production as shown in Table III. In the case of growing animals, it is not possible to quantify precisely the energy requirements without knowing the expected rates of growth of the body components, either in terms of chemical constituents (daily retentions of protein and lipid) or of daily amounts of tissue deposited (lean and fat). The energy content of gain tends to increase during growth as a greater proportion of fat is deposited and the water associated with protein decreases. It is inversely related to muscle: fat ratio, so that the dietary-energy cost per unit of gain decreases following the genetic improvement of lean-tissue growth potential. Therefore, the composition of gain varies according to age, sex and genotype. For a given level of liveweight gain, the leaner the pig, the lower the amount of energy or feed required and the better the feed conversion ratio. Alternatively, the increase in both daily liveweight gain and lean-tissue content results in a sustained level of feed intake with a further improvement of feed efficiency. In European countries the practice of feed restriction according to a scale based on liveweight or age for maintaining a low rate of fat deposition in the carcass is still widespread. But the genetic improvement of lean genotypes allows a progressive increase in the daily feed supply to a level close to appetite, i.e., approximately to 3-3.5 times maintenance level, or 0.9-0.95 of ad libitum intake.

Milk production

Lactation

Uterine deposits Maternal deposits Maternal + uterine deposits

Gestation

Growth

Productions

k1=0.70-0.75 (av. 0.72)

/%= 0.40 kn = 0.75-0.80 kges t = 0.70-0.75

k s = 0.65-0.75 (av. 0.70)

kp=0.40-0.80 (av. 0.55) kf=0.70-0.80 (av. 0.75)

k~ = 0.80

Maintenance

Protein deposition Lipid deposition

Efficiency of ME utilization

Type of expenditure

420-460

Growingpig

19.0-21.0

Finishing pig

1.9-2.1

100 days gestation

Milk production (kg day -1 ) Amount of exported eJlergy (MJ day -~)

6-7 29.0-33.5

23.0-27.0

Multiparous sows

12.5-23.0

Maternal deposits ( M J kg - 1 gain )

12.5-17.0

Average 25-100 kg W

42 54

kJ ME g-~ deposit

460-480

Sow

5-6

Primiparous sows

Energy content of milk: 4.4-4.8 MJ k g - 1

0.420-0.500

70 days gestation

Uterine deposits ( MJ d a y - ~)

8.0-8.5

Piglet

Energy content of gain (MJ kg - ~)

1.8 1.3

kJ ME k J - ~deposited energy

460-630 (av. 500)

Piglet

Energy requirement (kJ ME k g - 1 W °'vS)

Mean level of expenditure

Factorial components of energy requirements in pigs (from Henry and Noblet, 1986; Noblet and Etienne, 1987d,c,b)

TABLE III

315

Poultry The specific feature of poultry feeding is that it is based on the flock as a unit, the requirement of which is the result of different requirements between individuals. Therefore energy concentration in feed is of importance under practical conditions: for details see the review of Leclercq (1986). In order to meet the energy requirement, the diet should contain a minimum energy concentration. Feed intake in birds is largely dependent on dietary energy content, although with high energy concentration they tend to exhibit a luxury feed consumption. During the rearing period the energy content of the diet should be on average 11.5 MJ MEn kg -1 for chicks and between 11 and 11.5 MJ MEn kg -1 for pullets. It should not be set below 10.8 and 10 MJ MEn kg -1 in chick and pullet diets, respectively. High energy rations may easily lead to too intensive growth. In order to limit growth rate it is common to restrict the level of feeding slightly during rearing pullets of laying breeds, while the intensity of feed restriction should be greater in meat-type pullets. With broiler chicks an increased energy content (with a constant energy: protein ratio) results in increased final weight and decreased feed intake, i.e. an improved final feed efficiency; the higher the energy content in feed, the fatter the broilers. Whereas a feed-energy content of 12.3 MJ MEn kg -1 is sufficient during the first days of life, the fattening rations should contain at least 12.75 MJ, and preferably 13 MJ MEn kg-1; the determining factor is the cost per energy unit. The diets for laying hens of light and medium breeds should contain between 10.5 and 12.5 MJ MEn kg-~: the optimum recommended level is within the range 11-11.5 MJ MEn kg -1 (10.5-11 towards the end of the laying period). Higher energy content may cause fatty livers and energy luxury consumption ( about 10-30 kJ h e n - 1d a y - 1per 0.4 MJ MEn k g - ~increased energy content). Laying rate is not influenced by feed-energy content, but egg weight is. With each 1 MJ MEn kg-1 increase in feed energy content the egg weight is raised on average by 0.5%, i.e., 0.3 g increase in a 60-g egg. Increasing feed energy content does of course allow an improved feed efficiency, but, owing to the mentioned energy luxury consumption, controlled feeding is recommended. With breeding hens of meat type, a feed energy content of 11-11.5 MJ MEn kg-~ is common, but here again restrictive feeding is absolutely necessary. The energy requirement per bird and per day can also be calculated by the factorial method. During the last decade a great number of equations have been proposed, taking into account mean body weight, liveweight change, egg output and environmental temperature.

Protein Protein requirements need first to be expressed in terms of essential amino acids (EAA). Protein level as such has a limited and variable significance since

316 it is adjusted to meet the requirement for the most limiting EAA, generally lysine. Therefore, the recommended protein level in the different instances is only indicative for the commonly used diets, and depends on the pattern of the combination of protein sources. Protein quality of the diet is thus defined by the percentage of lysine in the protein: generally 5.0% in growing pigs and lactating sows, and 4.5% in pregnant sows. Because of the relative constancy of the AA composition of deposited protein for a given physiological status, the amounts of recommended amino acids are derived through constant ratios to one of them as a reference (lysine) (A.R.C., 1981 ). In the same way, the AA requirements may be expressed in the form of "ideal protein" which reflects a constant pattern of EAA (70 g lysine kg-1) and an optimum balance between them. Supplementing practical diets with the limiting AA (lysine) in the free form allows a decrease in total protein content (one to two percent depending on the AA profile of the contributing protein sources), i.e. the lower the percentage of lysine in dietary protein (as with wheat versus maize ), the higher the amount of spared protein with supplementary lysine. Recommended levels of practically balanced protein after lysine supplementation have thus been suggested (I.N.R.A., 1984), as an intermediary step towards ideal protein to meet the requirements for both EAA and non-essential nitrogen. Protein and AA requirements in growing pigs vary according to the rates of deposition of body tissue components (lean, fat), depending on age, sex, genotype and level of feeding. In breeding stock they depend on the level of reproductive performance, as is the case for the yield of milk which is itself related to litter size in lactating sows. The increase in the potential for lean tissue growth is associated with a higher daily requirement for protein and EA. Since energy density of gain is lower in lean compared to fat animals, this results in even greater protein and AA requirements according to energy or in percentage of diet. For instance, in the special case of lysine, the factorial method suggested by Wiesemiiller (1984) permits the prediction of the daily requirement from liveweight (W, maintenance component) and daily retained protein (RP), according to the following equation Lysine (gday -1) =0.1 W°75 ( k g ) + R P (g)×0.074/0.6 This allows a correction of the daily recommended supply according to the level of daily gain. For 100 g increase in gain, the daily requirement for lysine is increased by 1.8 g, on the basis of 1 g lysine deposited (7.4% of deposited protein and 15% protein in gain) and a rate of 0.60 lysine deposited from total intake. In the absence of a precise correction for the requirements for the rate and composition of gain the recommended allowances for given categories of pigs should refer to the optimum level of performance, i.e. females in place of castrates for lean deposition during the growing-finishing phase. The requirements for protein and AA are most commonly given in total

317

amounts, so that the recommendations may differ between countries according to the characteristics of the reference diet used for collecting experimental data. Some attempts have been made to express the AA requirements in available form. In The Netherlands, specific recommendations are formulated for total digestible lysine, as well as methionine and cystine. In Denmark, the digestible amino acids included in the recommendations are simply estimated from the apparent digestibility of total protein.

Poultry The protein (IXP) for amino acid requirement, as in the case of energy, is dependent on the deposition (growth, egg) and maintenance requirement (a function of body weight). For one bird, it may be written in the following formula:

IXP=b. W-+

ADG'c (XP) kg

O'c (XP) k0

which may be simplified to IXP---b-W + a. (ADG,O) where: IXP =protein intake in g or amino acid intake in mg per hen and per day; b -- maintenance requirement per kg body weight; a-- requirement per g weight gain or per g egg output; W (liveweight) ( in kg), ADG (average daily gain) (g day- 1), c (XP) = content of protein in gain and eggs; O ( g h e n - 1 d a y - 1) _ egg output; kg and ko = the efficiencies of ME utilization for liveweight gain and egg production. In practice, the problem is not to feed one bird, but a flock of birds. For the requirement of a flock the "Reading flock response model" has been suggested (Curnow, 1973; Fisher et al., 1973). The essential feature of the model is to consider the response of an individual hen as a simple factorial model and then to derive the flock response as the integrated average of a large number of individual responses. Depending on the costs of single amino acids, the optimal amino acid supply for maximum performance may differ from that corresponding to maximum monetary profit. With adjustment of requirements according to these economic circumstances the optimum dose of amino acid can be determined by the following equation (Fisher, 1973; Fisher et al., 1983 ):

AAIopt =a O+b W+ x ~f a2a~ +b2a2w + 2ab'r'ao "aw where: AAIopt= AA dose which equates marginal costs and marginal income; a = A A (mg) per unit output, O; b = A A (mg) to maintain unit body weight, W; x = the deviation from the mean of a standard normal distribution which is exceeded with probability ak in one tail, _xbeing defined as above, k being the ratio of cost per mg AA or value per unit O; ao, aw = standard deviations of O and W; r = correlation between O and W. The factorial calculation of the amino acid requirement has mainly been applied for laying hens. Similar calculations have been developed for chicks,

318

pullets and broiler chicks, but to a minor extent (Fisher, 1983; Boorman and Burgess, 1986). The requirements of available amino acids for a flock of laying hens with an average body weight of 1.8 kg and an average laying rate of 50 g egg output per day have been calculated from the data of Fisher (1983). The amounts in mg hen -1 day-1 are the following: arginine, 647; histidine, 235; isoleucine, 584; leucine, 884; lysine, 830; methionine, 325; threonine, 484; tryptophan, 176; phenylalanine+tyrosine, 929; valine, 696. For calculating the necessary amino acid contents in the feed, the availability (or digestibility) figures and daily feed intake are to be taken into consideration.

Feed requirement per standard animal produced In order to facilitate the summing up of the nutrient requirements of the total pig population within a given country and to compare these with the available and needed feed resources, it is appropriate to define a standard animal which is representative of the 3 main categories of pigs contributing to the final production, i.e. breeding stock ( reproductive sows, boars and replacement gilts) for that part of nutrients required per pig produced annually per sow, post-weaning piglets ( 3-4 weeks of age to 25-30 kg liveweight on average) and growing-finishing pigs (25-30 to 100-110 kg liveweight on average). Attempts may be made, as a guideline, to estimate the total amount of feed required per standard pig produced and which is representative of the most common type of production in Europe. As shown in Table IV, to produce a 100TABLE IV

Total amount of feed per standard pig produced ~ Categories of pigs

Piglet

Growing-finishing Amount sow- 1 pig year- 1

Pre-starter Starter Standard energy density

14.6

14.6

Total amount per pig produced 2

Pregnancy Lactation 13.4

12.5

13.0

(MJ DE kg -1)

Liveweight interval (kg) Age interval (days) Avg daily gain (g) Feed conversion ratio Total feed intake (kg)

Energy intake (MJ DE) Protein intake (kg)

5-10 26-40 200-250

1.4 5.5

1.2

10-25 40-70 500-550 1.65

25-100 130-180 700-750 3.2

25 30.5

240

445 4.8 6.0

3200 40

130-180 300-400 880

140-180 320 1200

15 160 10

340 4540 56

1Amounts of feed and nutrients per standard pig slaughtered at 100 kg liveweight. 20n the basis of 17 pigs produced per sow and per year in the herd. Liveweight interval 1-100 kg.

319 TABLE V Energy and protein balance in broiler meat production

Input Breeding hens, meat type 12.7 kg chick and pullet feed 1 39.7 kg layer (inc. 10% males) feed1 Total per hen Total per chick2 Broiler 2.45 kg broiler feed3

ME (MJ kg -~)

XP (gkg -1)

Total ME (MJ)

Total Protein (g)

11.5 11.5

165 160

146 457

2096 6352

603 4.75

8448 66.5

13

225

Total Metabolizability ( % ) Gross energy Output Carcasses 4 1.058 kg oven-ready+ giblets Output X 100 Input

10.5

157

31.85

551.25

36.6 77 47.5

617.75

11.1

166

23.4

26.9

1Including losses and culls. 2127 chicks per hen. 31.4 kg WX 1.75 FE (1.36 kg WX 1.80 FE) =2.45 kg broiler feed. 43.2 kg W breeding hen + 0.475 kg W breeding male (10% of 4.75 kg) = 3.675 kg W total per hen: 127 (chicks per hen) = 0.029 kg W breeding hen/male per broiler + 1.400 kg W broiler = 1.429 kg W total per broiler × ~-~ (74% oven-ready + giblets) = 1.058 kg carcass (oven-ready + giblets). ME = Metabolizable energy; XP = crude protein content; FE = feed efficiency, i.e. amount of feed (kg) kg -1 liveweight (W) gain. kg pig at s l a u g h t e r requires o n average 350 kg b a r l e y equivalent, 17% o f which c o r r e s p o n d s to t h e p r o p o r t i o n o f feed n e c e s s a r y to m a i n t a i n t h e b r e e d i n g stock a n d to p r o d u c e e a c h pig at weaning. T h e a m o u n t of p r o t e i n n e c e s s a r y to produce a 100-kg pig is w i t h i n t h e range o f 50-60 kg. T h e p r o p o r t i o n of p r o t e i n f r o m cereals varies f r o m 50% or m o r e in c e r e a l - b a s e d diets to 10% or less w h e n b y - p r o d u c t s are t h e m a j o r c o n s t i t u e n t s of t h e diet, as in T h e N e t h e r l a n d s . T h e t o t a l efficiency values of e n e r g y a n d p r o t e i n utilization for broiler fatt e n i n g a n d egg p r o d u c t i o n o f laying h e n s o f light b r e e d s are given in T a b l e s V a n d VI, along w i t h feed i n t a k e d a t a p r o v i d e d in T a b l e VII.

320 TABLE VI Energy and protein balance in egg production

Input Breeding hens, light breeds 1.6 kg chick feed 6.2 kg pullet feed 1 36.5 kg layer (incl. 8% males) feed2 Total per hen Total per chick 3 Laying hens 1.6 kg chick feed 5.8 kg pullet feed 48.9 kg layer feed4

ME (MJ kg -1)

XP (g kg -1 )

Total ME (MJ)

Total Protein (g)

11.5 11.3 11.3

185 145 165

18.4 70.1 412.5

296 899 6023

501 6.3

7218 90

18.4 65.5 552.6

296 841 8068

642.8 75 857.1

9295

132

2395.4

11.5 11.3 11.3

185 145 165

Total Metabolizability (%) Gross energy Output Eggs 5 Carcasses6 (1.200 kg oven-ready + giblets )

6.5

118

11.4

175

Total Output X 100 Input

13.7

210

145.7

2605.4

17

28

1Including losses and culls, no restriction. 280 chicks per hen. 321-66 week--315 daysX 116 (110 g h e n + 6 g) g. 421-80 week = 420 days X 120 g X 0.97% livability (average during the year). 5325 eggs X 62.5 g egg weight = 20.3 kg egg mass output. 81.6 kg W breeding hen: 80 (chicks per hen) = 0.020 kg W breeding hen per laying hen + 1.692 kg W laying hen (1.8 kg W X 0.94% livability) = 1.712 kg W total per laying hen X ~ (70% oven-ready + giblets) = 1.200 kg carcass (oven-ready + giblets). FUTURE DEVELOPMENTS IN FEED EVALUATION AND NUTRIENT REQUIREMENTS IN NON-RUMINANTS

Future developments in feed evaluation Improvement of energy systems T h i s is a p r o b l e m o f i n c r e a s i n g r e l e v a n c e f o r p i g s . T a b l e s o f D E a n d p a r t i c ularly of ME values should be based more extensively on direct calorimetric

321 TABLE VII Feed intake of birds Adult birds

Laying hens light breeds medium breeds Breeding hens meat type dwarf type Turkey breeding hens Small body weight Large body weight Guinea fowl breeders Japanese quail hens light type meat type Peking duck breeders Muskovy duck breeders Geese breeders Growing birds Broiler Broiler Chick and pullets light breeds medium breeds meat type Turkey broilers Turkey ~ Turkey ~ Guinea fowl broilers Growing Jap. quails Growing pheasants Peking duck broilers Muskovy duck broilers ~ Muskovy duck broilers ~ Goslings Goslings

Egg output g ~ -1 day-1

MJ MEn kg- 1

Feed intake g ~ -1 day-1

40-60 40-60

11.25 11.25

105-125 115-135

30-50 40-60

11.25 11.25

145-165 120-130

40-60 40-65 20-40

12.1 12.1 11.9

140-160 220-245 90-110

9 10 40-70 30-70 50-110

11.25 11.25 10.9 11.7 10.5

23 30 220-265 150-185 300-420

Age (weeks)

kg/period

1-6 1-8

13.3 13.3

1-20 1-20 1-20 1-9 1-16 1-24 1-12 1-6 1-5 1-7 1-10 1-12 1-8 1-12

11.6/11.25 11.6/11.25 11.6/11.25 12.5/12.8 12.5/12.8 12.5/12.8 12.5 12.5 11.7 12 12.1 12.1 11.7 11.7

3 5 7.5 8 10 6 20 50 4.7 0.6 0.5 7.5 7.5 13 13 22

determinations along with suitable corrections for changes in composition characteristics for a given type of feed. In the case of ME, there is a need to standardize the mode of calculation and the use of correction factors according to variations in protein level and amino acid balance as well as for methane production in relation to the contribution of fermentable substances.

322 Besides DE and ME, which are clearly defined as a system, it is necessary to reconsider a net energy system which reflects the real value of balanced feeds for producing lean meat from pigs. This implies a better understanding of the variations of ME utilization and the specific needs for the different types of production and for maintenance according to genotype, physiological status, feeding conditions (level of feeding, fibre content and composition, protein level and amino acid balance ) and environmental factors (temperature, housing conditions and social environment). For the future the NEF system is likely to be less appropriate with further progress in selection for rapid leantissue growth. Nevertheless, for practical application, it has to be proved that net energy gives a significant advantage over ME for predicting the energy value of feeds in modern pig production. If so, a mode of calculation of a welldefined NE, i.e., for fast-growing lean-type pigs at a high level of feeding, has to be established from DE or ME or from digestible nutrients. In addition, differences in net energy utilization between the different categories of animals during growth or reproduction need to be established in order to correct the energy requirements expressed in the appropriate system according to the physiological status. This should allow a logical conversion from one energy system to another and would facilitate the comparison between systems and requirements from a given country to the others. A problem of growing importance with the use of diversified feedstuffs and complex diets is that of non-additivity in digestive and metabolic utilization. Digestive interactions between dietary components, i.e., between fibrous constituents and other nutrients (protein, lipid and soluble carbohydrates) need to be studied in more detail in relation to the effects of plane of feeding, by taking into account the end-products from fermentable substances in the hind gut and their metabolic use compared with the nutrients absorbed in the small intestine. For an accurate prediction of the energy value of single and compound feeds from dietary characteristics, either in crude or digestible amounts, it would be of great benefit to set up a new basis for nutrient partitioning in replacement of the traditional Weende method, by substituting for DXX with/more homogeneous fractions i.e., starch, sugar, and fibre constituents (cellulose, hemicellulose, lignin, pectins). This requires definite resolutions for revised biochemical procedure in feed analysis, especially for structural carbohydrates, with high enough precision and for large serial analyses. Following D.L.G. (1984) recommendations, Hoffmann and Schiemann (1985) already suggested an improvement in the assessment of the energy value (NEF) of pig feeds, by including the amount of fermentable substances in the prediction equation, in addition to digestible protein and fat, starch, mono- and disaccharides, and digestible pectins. On the other hand, it is necessary to predict more accurately the energy value of fats and the fat content of feedstuffs by considering their fatty acid pattern. It is expected that the development of in

323

vitro methods will bring some benefit for a rapid evaluation of the energy content of compound feeds for pigs and poultry.

Protein evaluation on the basis of amino acid availability For the future protein evaluation in pig and poultry feeds should be extended to a precise assessment of the availability of the different essential amino acids, through the measurement of apparent and/or true digestibility of protein and amino acids at the end of the small intestine for pigs and the use of caecestomized birds. The methodological constraints of ileal digesta collection or sampling from cannulated pigs could be avoided with the use of the ileo-rectal anastomosis technique, which allows total ileal excreta collection in digestibility crates for rapid routine measurement of ileal protein and amino acid digestibilities. A significant progress in this methodological procedure is to be expected, in order to provide a standardized technique adapted to large series of determinations. The measurement of ileal digestibility of protein and amino acids, especially for lysine, methionine and cystine, threonine and tryptophan, which are likely to be the most limiting in current feeding practice, preferably after correcting for endogenous losses, will allow: (i) a survey of amino acid availability within a wide range of novel feed ingredients; (ii) the assessment of the effects of technological treatments as a means of improving the nutritional value of potentially-available feed resources; (iii) the study of dietary digestive interactions between protein and fibre as well as, fat and antinutritional substances. The development of indirect in vitro techniques should also be explored for a rapid evaluation of protein quality in feeds by reference to ileal procedure. Future prospects for determining nutrient requirements Factorial estimation of the requirements according to performance level and production factors Energy as well as protein and amino acid requirements will have to be determined essentially on the basis of the factorial approach in relation to the level of performance (liveweight gain and tissue composition of gain, litter size, weight change during pregnancy and lactation, milk yield) and production conditions ( slaughter weight and carcass quality, climatic environment). Future recommendations for amino acids will preferably be given on an availability basis (ileal digestibility). In any case it is necessary to correct the requirements according to the rates of nutrient or tissue deposition instead of simply considering mean recommendations for an optimum level of performance. The adequacy of the factorial approach will be controlled by feeding tests. Consequently, more elaborate methods need to be applied in feeding and balance trials for estimating tissue and nutrient deposition, in order to relate production response (lean and fat tissue gain, maternal tissue changes, milk

324

production) to nutrient input in quantitative terms. The in vivo appraisal of body composition, especially in pigs, will bring a positive contribution to the assessment of initial lean and fat content according to liveweight and thus facilitate the use of comparative slaughter techniques along with balance trials.

A need for new criteria in the assessment of protein and amino acid requirements The concept of "ideal protein" for growth in pigs, which is simply based on a constant amino acid composition of deposited protein, thus resulting in fixed ratios between essential amino acids and lysine as a reference, should be reconsidered in relation to the differential metabolic fate of essential amino acids. The amino acid balance will have to be modulated according to protein turnover rate ( synthesis, degradation) and amino acid catabolism (oxidation) to complement the observations which have been restricted until now to protein and amino acid accretion. Specific problems related to future developments in feed resources In connection with the increasing use of supplementary industrial amino acids ( lysine, methionine, and in the near future tryptophan and threonine), one may expect a significant saving of dietary protein through the improvement of amino acid balance. This is in favour of more research effort towards a better understanding of the sparing effect of the amino acid balance on energy utilization, and consequently on feed energy value, in relation to protein level as evidenced by recent findings (Noblet et al., 1987 ). In addition to protein and energy saving, the stimulatory effect of improved amino acid balance on voluntary feed intake should provide maximum benefit from high performing animals for lean meat production in conjunction with possible growth manipulations and use of biosubstances. On the other hand, besides covering the dietary needs in the appropriate way, more attention should be given in the future to decreasing the excretion of nutrients (nitrogen, phosphorus) with the aim of avoiding soil contamination. CONCLUSION

With the rapidly increasing intensification of pig and poultry production during recent decades, and the subsequent steady improvement of feed conversion efficiency in meat and egg outputs, there has been significant progress in the evaluation of energy and protein in single feedstuffs and complete feeds for both non-ruminant groups, pigs and poultry. Feed-energy evaluation in pigs is characterized by diverse systems in use including digestible energy, metabolizable energy and net energy for fat formation or for growth, along with various ways of calculating the energy value within each system, either from direct calorimetric measurements with correction factors for differences in

325 chemical composition or, most commonly, from digestible nutrients. In contrast to pigs, energy evaluation in poultry is uniformly based on metabolizable energy, which is usually corrected to zero nitrogen retention. In both pigs and poultry, with the advancement of knowledge in feed composition and nutrient utilization, the prediction of energy value has gained in accuracy, and allows a good adjustment of feed supply to the requirements when there are unavoidable changes in feedstuff characteristics. Still the problem remains of developing the most adequate energy system, especially for pigs, which can closely predict production performance. More research is needed to produce an additional improvement, for instance by considering the use of a net energy system for growth and lean meat production. An improved nutrient fractionation system is needed to replace the traditional Weende procedure and the so-called digestible nutrients. This will enable the identification of the appropriate digestible nutrients according to the digestion site in the prediction equations by taking into account digestive interactions between fibrous components and the other nutrients. It might appear surprising that less progress has been made in protein evaluation on an availability basis than in evaluating energy. Despite a good knowledge of the amino acid composition of protein in feedstuffs, protein evaluation is still restricted in most countries to apparent protein digestibility, and dietary supply is generally based on crude amounts of protein and amino acids. For the near future there is an urgent need to encourage systematic measurements of digestible amino acid at the ileal site for pigs, or the use of caecectomized birds, whenever possible with a standardized procedure, in order to set up extensive tables taking into account quality changes between, as well as within, feedstuffs, depending on technological treatments. Nutrient recommendations for non-ruminants have been mainly produced up to now for an average level of performance on the basis of feeding trials. For the future, further expected improvement of production capabilities will im duce a widening of animal performance and this will necessitate diversification of the recommended allowances according to production conditions. The im creasing use of the factorial approach for predicting nutrient requirements, based on a quantitative appraisal of requirement components and the rates of nutrient utilization, will provide a means for a better adaptation of feed supply to animal performance and production objectives. This will also allow more uniformity in the presentation of the systems in use in the different European countries for predicting feed energy and protein value as well as nutrient requirements. REFERENCES Alderman,G., 1985.Prediction of the energyvalueofcompoundfeeds.In: W. Haresignand D.J.A. Cole (Editors), Recent Advancesin AnimalNutrition, Butterworths, London,pp. 3-52.

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329

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Appendix A. Pigs

GENERAL

The available energy systems (DE, ME, NE for fattening or for growth) are used in practical conditions for pigs in the different European countries with specific adaptations according to the method of calculation (digestible nutrients, prediction equation, energy unit) and feed characteristics (composition, digestibility coefficients). The inventory of the available systems for energy and protein evaluation is listed in Table AI. Nutrient recommendations are given in amounts per kg of standard feed of known energy value or in amounts per day on liveweight (W) basis, occasionally with specific corrections according to production performance (W gain, net gain during pregnancy, milk yield or litter size). With regard to essential amino acids (EAA), lysine is chosen as a reference, the requirements for the other EAA most likely to be limiting (threonine, tryptophan, methionine plus cystine) are derived from known ratios of EAA to lysine. Tables AII-AIV provide comparative protein and lysine recommendations in different European countries for piglets and growing-finishing pigs, pregnant and lactating sows, on the basis of a standard diet of a given energy value. Prediction equations of the energy value of mixed feeds from digestible nutrients, when they are known, or simply from crude chemical composition, are given in Tables AV and AVI. A brief description of the available feed-evaluation systems and feeding recommendations is given for the different countries with references.

TDN OFU, EFs UNp OFU OFU

(k)EFs

NEF NEF NEF

MJ MJ SFUN ry MJ

NKF NKF Danish

NEF ¢ NEF ¢

NKz

MJ MJ MJ kcal, SFU

EW EW FEB kcal MJ

Rostock eqn., dig. nut. Rostock eqn., dig. nut.

Crude nut. Dig. nut. Dig. nut. Dig. nut. as in F.R.G. Rostock eqn., dig. nut. Rostock eqn. dig. nut. Rostock eqn., dig. nut. Rostock eqn., dig. nut.

Rostock eqn., dig. nut

Rostock eqn., dig. nut. Rostock eqn., dig. nut. Dig. nut. Direct measurement (DE) Dig. nut. (Rostock eqn.), correction BFS d

Mode of measurement or calculation

+ + + + + + + + + + + + + + +

+ + + + +

+

+ +

+ + +

+ + +

+ + + + +

+

+ + +

+

+ + +

Digestible AA

DXP

Ideal protein (growth)

Faecal dig. Faecal dig. Calculation from dig. XP

Mode of measurement or calculation

dBacterial Fermentable Substances.

aNEF: Net energy for fattening: Rostock equation using digestible nutrients (dig. nut.). NKF: Netto kalorie fiir Fett (M~llgaard, 1929). blW=8.78 MJ kg -1 (2100 kcal); 1 FEB= 7.72 MJ kg -1 (1845 kcal); 1 EFs= 14.65 kJ NEF8 (3.5 kcal); 1 ry=barley equivalent; 1 UNp= 1 EFt, OFU = Oat feed unit. cUsing Dutch tables.

+ +

+

+ +

+

+ +

+ + +

Portugal Spain Switzerland Sweden Norway Finland Austria Yugoslavia G.D.R. Hungary Czechoslovakia Poland Romania Bulgaria U.S.S.R.

+ +

+

+ + + +

+

NEF ¢ NEF ¢ Danish NEI~

Energyb unit XP Total AA

NE a

DE

ME

Protein

Energy

U.K. Ireland Greece Italy

The Netherlands Belgium Denmark France F.R.G.

Country

Energy- and protein-evaluation systems in use for pigs in European countries

TABLE A I

b~

C~

60 50-90 60-100 60-80 60-120 60-100

35-100 30 25-60 20-40 35-60 35-60

NL DK F FRG GDR USA DK UK F FRG GDR USA

15-35 20 15-50 15-35 20-35

8-15

Specific liveweight (W) or W interval (kg)

NL DK UK GDR USA

NL DK UK F FRG GDR USA

NL UK F FRG GDR USA

Country ~

130

112 b 150 140

140

170 173

160

156d

180

180 190 195

2OO

210 220 212

110

125-135

120

130-140 140-155

160

150-170

160

150-170 160-190

190

150

7.8 7.0 7.0 6.5 5.7

min. 8.0 8.7 7.0 6.1

min. 8.0

11.0 9.5 7.0

10.0

12.5 12.5 10.3 9.5 7.9

11.0

12.0 14.0 14.0 11.3 13.0 9.5

Total

XP

DXP

Lysine

Protein

1 FE, 13.0 M J DE 13.4 M J DE (12.7 MJ ME) 12.0 MJ ME 0.62 kEF8 (900 g DM kg -1) 14.2 M J DE

1.3 EW 1 FE~ 13.4 M J DE (12.7 MJ ME) 12.0 MJ ME 0.60 kEFs (900 g DM kg -1) 14.2 MJ DE 6.8 7.0-8.0

6.5-7.3

1.03-1.07 EW 1 FE~ 13.0 MJ DE 0.62 kEF~ (900 g DM kg -1) 14.1 MJ DE

1.0-1.1 EW 1 FE. 13 MJ DE 14 M J DE (13.3 MJ ME) 12.0 MJ ME 0.62 kEF~ (900 g DM kg -~) 14.1 M J DE

1.1 EW 13 MJ DE 14.5 MJ DE (14.0 MJ ME) 12.0 MJ ME 0.61 kEFs (900 g DM kg -1) 14.6 MJ DE

8.9 8.0-9.0

8.10

Dig.

Energy content of standard feed k g - 1

aNL, The Netherlands; DK, Denmark; UK, United Kingdom; F, France; FRG, Federal Republic of Germany; GDR, German Democratic Republic; USA (N.R.C., 1979). bGenerally under feed restriction: feeding scale in European countries: 700-750 g ADG between 20 and 100 kg W; in U.S.A., ad libitum feeding. CNL, faecal digestibility; DK, calculated from protein digestibility. dIdeal protein.

Finisher b

Starting 25-30 kg W

Growe~ Sta~ing 15 kg W

Starter (10-20 kg W)

Piglet Pre-sterter ( 5-10 kg W)

Categories of pigs

Comparison of nutrient recommendations for growing pigs in some European countries (g kg- I standard feed)

T A B L E AII

5~

c~

1 2 1 2 1

F.R.G.

2.0 2.35 2.2 f 2.6 1.8 216

250 300 165 200

150 200 200-260 300-400 min. 180 min. 145 300

120

125 e

120

120 120 90-110 8.6 10 (11-12) d 11 13 10 12 7.7

18 22

Total

8-11 12-16

Dig.

XP

XP

DXP

A m o u n t d a y - 1 (g)

gkg -~ feed

A m o u n t d a y -~ (g) DXP

Lysine

Protein

al, 12 firstweeks (or total pregnancy); 2, last 4 weeks. bFaecal digestibility. ¢Computed from protein digestibility. dWithin parentheses, revised recommendations. e4.5% lysine in protein. qVIultiparoussows: for primiparous sows, 1:2.0;2:2.6.

U.S.A.

G.D.R.

U.K. France

Denmark

1a 2a 1 2 1 1

T h e Netheflands

2.5 3.0 2.0-2.4 3.2-3.8 2.0 2.5

State of Standard gestation feed (kgday -I)

Country

Comparison of n u t r i e n t r e c o m m e n d a t i o n s for p r e g n a n t sows in some E u r o p e a n countries

T A B L E A III

4.2

5.0

(4.5)d 5.5

4.3 4.0

min. 7.2 7.5

Total

3.5-4.5 c

5.9 b

Dig.

g k g - 1 feed

14.2 M J D E

0.55 K E F s kg -1 D M

12.5 M J M E

12.5 M J D E

1 FEs

0.97 E W

Energy c o n t e n t of s t a n d a r d feed kg -1

f~

10 _+1 10 -{-1 10 10 +_1 10 +_1 10 _+1

The Netherlands

"1% W of the sow + 0.4 kg per piglet. bFaecal digestibility. CThird week of lactation. dComputed from protein digestibility. ePrimiparous: 700 g day- i. f5.0% lysine in protein.

U.S.A.

G.D.R.

F.R.G.

U.K. France

Denmark

Litter size (no. piglets)

Country

5.6-6.1 0.4 a 6.0 c 0.4 5.25 5.5 0.3 5.1 0.4 5.35 0.36 5.5

Standard feed

715

800 75

825 800 e

730-800

640 60 665 45

660

780

130

150

145-160 ~

155 145

130 130

40 4 40 2.8 31.9

33 33

Total

34

39

Dig.

XP

XP

DXP

Amount day- 1 (g)

g kg-I feed

Amount day-1 (g)

DXP

Lysine

Protein

Comparison of nutrient recommendations for lactating multiparous sows in some European countries

TABLE A IV

5.8

7.5

7.5-8.2

6.3 6.0

min. 7.5

Total

g kg- l feed

1 FE~

6.5 d

14.2 MJ DE (13.4 MJ ME)

0.58 kEFs

12.5 MJ ME

12.5 MJ DE 13.0 MJ D E

0.97 EW

5.9 b

Dig.

Energy content of standard feed kg- 1

c~ c.~ ¢91

336 TABLE A V Prediction equations of energyvalue of singleor mixedfeeds(MJ kg- 1feed)from digestiblenutrients (g kg- 1feed)for pigs Energy Regressioncoefficients system DXP DXL DE ME

0.0242 0.021 0.0215

0.0394 0.0374 0.0377

References DXF

DXX

0.0184 0.0144 0.0173

0.0170 0.0171 0.0173

Hoffmannand Schiemann(1980) Hoffmannand Schiemann(1980) Just {1982)

ENERGY SYSTEMS

Digestible energy (DE) systems used in France, U.K., Ireland, Greece, Italy, Spain, Portugal, Switzerland, Poland, Hungary and Bulgaria Nutritive value France. There is no official energy system for practical use in pig feeding and the choice of the available systems is open. The DE values obtained from direct calorimetric measurements on a wide range of feedstuffs have been used to set up tables of feed composition and nutritive value in I.N.R.A. (1984), along with estimated ME values from DE according to DXP.

ME {MJ kg -1) =0.99 DE (MJ kg -1) - 0 . 2 9 DXP (g) The tabulated values are expressed in kcal kg- 1. For some feedstuffs, prediction equations are provided for correcting the DE value from crude-fibre content. In practice, the E system is used along with the NEF system as applied in the Dutch tables (CVB, 1983), which are based on the NEF system, with the first equation proposed by the Rostock group (Nehring, 1969).

U.K. and Ireland. For feeding pigs preference is given to the DE system, which was chosen by A.R.C. (1981) for expressing feed-energy value and energy requirements (MJ kg- 1). Greece. There is no official energy system for practical use and the choice of the available systems is open. However, the system most commonly used is the one based on DE. In this respect DE in MJ is predicted from tabulated proximate-composition data using the following equation proposed by Schiemann et al. (1971): DE (MJ kg- 1) __0.0242 DXP+ 0.039 DXL + 0.0184 DXF+ 0.017 D X X

5.75 5.62 5.53 5.74

Constant

0.0066 0.0040 0.0028 0.0021 0.0203 0.0180

XP

Regression coefficients

0.0252 0.0315

XL

*CV means coefficient of variation in %.

ME

DE

Energy system

-0.0178 -0.0149

XF

-0.0162 -0.0163

XX 0.68 0.69 0.70 0.69

GE -0.016 -0.016 -0.016 -0.017

NDF -0.035 -0.0223 -0.034 -0.024

ASH 0.27 0.34 0.25 0.33 (5.0) 0.54 (3.7)

RSD (CV*, %)

Prediction equations of energy value of compound feeds (MJ k g - 1) from crude chemical composition (g k g - 1) for pigs

TABLE A VI

0.887 0.956 0.893 0.960 0.76 0.8

R2

Pdrez et al. (1984) Morgan et al. (1987) P~rez et al. (1984) Morgan et al. (1987) Just et al. (1984) E.A.A.P. Working Group: provisional equation

References

338 with DXP, DXL, DXF and D X X in g kg- 1.

Italy. Both DE and ME (in kcal) are used, with a preference for DE. The conversion from DE to ME, for mixed feeds or for single feedstuffs, by taking into account crude-protein content, according to N.R.C. (1979) is: ME=DE (0.96-0.202 XP). In compound feeds, DE values are estimated from different available equations (Morgan and Whittemore, 1982; Kirchgessner and Roth, 1983; P~rez et al., 1984). Spain and Portugal. In Spain, there are no official recommendations on energy and protein evaluation, feed composition and feeding standards. In most cases DE is used as an energy unit (I.N.R.A., 1981, 1984 and A.R.C. tables and recommendations), but other systems like the Dutch system and the corresponding tables (C.V.B., 1983)are also utilized in practice. Committees have been appointed to advise on which system to adopt. In Portugal, the position for pigs is similar to that in Spain. Switzerland. The energy value for pigs is expressed in DE (MJ kg- 1). For complete rations based on concentrates, DE is calculated from proximate analysis of nutrients DE (MJ kg- 1) = 0.0190 X P ÷ 0.0335 X L - 0.0212 X F ÷ 0.0166 X X where XP, XL, XF and XX are given as g kg-1. This calculation is restricted to rations with ~