Multi-Site Pig Production

Multi-site Pig Production D. L. (“Hank”) Harris Department of Microbiology College of Agriculture and Department of Veterinary Diagnostic and Production Animal Medicine College of Veterinary Medicine Iowa State University

Iowa State University Press /Ames

Multi-site Pig Production

Multi-site Pig Production D. L. (“Hank”) Harris Department of Microbiology College of Agriculture and Department of Veterinary Diagnostic and Production Animal Medicine College of Veterinary Medicine Iowa State University

Iowa State University Press /Ames

D. L. (“Hank”) Harris, DVM, PhD, is professor, Department of Microbiology, College of Agriculture, and Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, at Iowa State University. Dr. Harris returned to academia after serving as vice president of veterinary services for a commercial breeding stock company. © 2000 Iowa State University Press All rights reserved Iowa State University Press 2121 South State Avenue Ames, Iowa 50014 Orders: Office: Fax: Web site:

1-800-862-6657 1-515-292-0140 1-515-292-3348 www.isupress.edu

Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by Iowa State University Press, provided that the base fee of $.10 per copy is paid directly to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923. For those organizations that have been granted a photocopy license by CCC, a separate system of payments has been arranged. The fee code for users of the Transactional Reporting Service is 0-8138-2699-3/2000 $.10. Printed on acid-free paper in the United States of America First edition, 2000 Library of Congress Cataloging-in-Publication Data Harris, D. L. (Delbert Linn) Multi-site pig production / D. L. “Hank” Harris.—1st ed. p. cm. ISBN 0-8138-2699-3 1. Swine. I. Title. SF395 .H297 1999 636.4—dc21 99-049092 The last digit is the print number: 9

8

7

6

5

4

3

2

1

In memory of Ken Woolley, Al Leman, and Lauren Christian Each contributed in many ways to the evolution of the swine industry, including concepts that led to modern-day multi-site pig production systems.

Contents

Foreword by R. D. Glock ix Preface xi Acknowledgments xiii 1. Introduction 3 2. Multi-site Rearing Systems 37 3. Exclusion and Elimination of Microbes 57 4. Immunity, Pig Performance, and the Emergence of Disease 79 5. Control of Common Infectious Swine Diseases 97 6. Policy Decisions and Opportunities for Owners and/or Senior Management 125 7. Management of Multi-site Rearing Systems 158 8. Breeding Stock Production 175 9. Standardized Nomenclature, Alphanumeric Notation, and Diagrams 187 10. Future Rearing Systems and Facilities 205 Index 209

Foreword

Multi-site Pig Production is the first comprehensive description of the most profound changes that have occurred in swine production methodology in many years. Techniques involving various forms of multi-site rearing have recently evolved. Dr. Hank Harris is singularly qualified to author this work because he has played a pivotal role in the initiation of techniques that are being applied throughout the world. The term isowean evolved from medicated early weaning (MEW), or isolated weaning, and was first used by Hank Harris. Its copyrighted status has been rescinded because it has become a common industry term. Terminology regarding multi-site rearing techniques has been somewhat disorderly and confusing. Information in this book provides final definition for a variety of terms that are being used to describe swine production methods. Various industry publications and glossaries have been considered in the formation of a framework for precise communication. A system of nomenclature is provided to facilitate more accurate future interactions between participants in swine production systems that involve multiple sites, buildings, and rooms with different age groups and functions. Multi-site Pig Production is designed for use by anyone interested in swine production. This includes students as well as production personnel. The writing style is easily understood and the book is arranged so it can be read in its entirety or it can be used as a chapter-specific reference. (However, no one should attempt to use this book without addressing the sections on definition of terms [Chapters 1 and 9].) The relaxed style of this book reflects the personality of the author, who has managed throughout his professional career to remain informal while providing profoundly innovative ideas. The reader may be challenged to seek further applications of some of the concepts that are presented. Major changes in disease management and, more importantly, in profitability have already occurred, but innovative applications of the information provided will result in even more significant applications. This book is a necessity for those seriously interested in the economic future of the swine industry. R. D. Glock, D.V.M., Ph.D. University of Arizona Veterinary Diagnostic Laboratory Tucson, Arizona ix

Preface

The thought of writing this book occurred to me for the first time while I was chairing a mini-symposium on multi-site production organized by Barry Wiseman and held prior to the Al Leman Swine Conference in 1997. The rather large amphitheater was filled to standing-room-only and the questions by the participants carried on well past the cocktail hour. As the symposium progressed, it became rather obvious that considerable confusion existed regarding terminology of multi-site farms and the elimination of infectious agents via isowean. In particular, Howard Hill and I couldn’t even agree on how to describe the Murphy Family Farms rearing system—a system that I helped design and that he works in every day. Several veterinarians in the room expressed the belief that multi-site production exacerbates the severity of porcine reproductive and respiratory syndrome (PRRS) outbreaks on pig farms. My reactions were Why is there so much confusion regarding a rather simple concept? (Pigs weaned in isolation away from adult swine have fewer infectious agents and grow faster on less feed.) Why can’t the other speakers and I answer all the questions posed by the participants? Does multi-site production really increase the severity of disease in some situations or is it simply due to other factors related to management and biosecurity?

Shortly after the mini-symposium, I was interviewed for a Morrison Group tape recording (see “From MEW to Multi-site Isowean Production,” Chapter 1). During the interview, those same reactions occurred plus there were more questions: How many others associated with the swine industry are having difficulty in successfully implementing multi-site technology? Are animal scientists, geneticists, pork producers, building companies, lenders, feed dealers, veterinarians, and students communicating effectively regarding multi-site production systems? Why are so many new and renovated farms using multi-site isowean technology?

The motivation to start (and finish) this book came from a fear that the Isowean Principle was correct in theory but not in practice. Was it possible that isolated weaning (isowean) should not be the basis for how most pigs in the world will be reared well into the next century? While attempting to answer this question, I learned many things by collecting information from the literature and by interviewing veterinarians and pork

xi

Preface

producers. As expected, not all of my original hypotheses were correct regarding the application of the Isowean Principle. But overall, I became convinced that there are many benefits to be gained by any-sized pork production operation if multi-site isowean technology is properly implemented. Thus, I felt compelled to explain the evolution, advantages, pitfalls, and practical application of modern-day multi-site pig production.

xii

Acknowledgments

Several individuals worked very closely with me; without their help the book would not have been finished. They are my wife, Isabel, who contributed constructive criticism to most chapters and made many significant suggestions, especially in the content of Chapter 9; Bob Glock, who edited the entire manuscript and wrote the Foreword—a true friend indeed; and Stephanie Wedel, who prepared the tables, figures, and manuscript on the computer. In the very early stages, Anita Nimtz was a very helpful assistant, and Susan Aldworth created the template for some of the illustrations. I am particularly indebted to my sons, Joel and Dill, and daughters, Wendi and Sue, for understanding my absences due to this project. There are many pork producers to thank. They are my dad, Arnie, for purchasing our first Duroc boar on the day I was born; my mom, Marie, for teaching me how to revive a chilled baby pig by the stove in our living room; my brother, Bob, for convincing me to minor in biochemistry; my sister, Patsy, and Mike Larson for use of their nursery for the first pseudorabies isowean trial; my mentors, Bill Switzer and Tom Alexander; Chuck Sand for building the first three-site farm in the world; Linus Solberg for his support even though he may disagree with the changes brought on by isowean; and Howard Hill for convincing me on the use of three-site production terminology. Many of the ideas and concepts in the book came from discussions with Joe Connor, Tim Loula, Paul Armbrecht, Steve Henry, Jack Anderson, Butch Baker, Bill Christianson, Jer Geiger, Barry Wiseman, Eldon Wilson, Jose Doporto, Jose Barcelo, Eldon Wilson, Hugh Dorminy, Randy Stoecker, and Gregg BeVier. Pork producers Gonzalo Castro, Gary Gausman, and Tim Cumberland kindly provided unpublished data found in some of the tables and figures. A special thanks to Richard Clothier for helping me create the term isowean and to Phil David for the removal of the trademark on the term by PIC (Pig Improvement Company, Inc.). The support of Iowa State University administrators is greatly appreciated and was essential for the book to be completed: Deans Richard Ross and Dave Topel, Provost John Kozak, and President Martin Jischke. I am indebted to the faculty colleagues who

xiii

Acknowledgments

willingly increased their teaching and advising duties during my sabbatic leave: Joan Cunnick, Jim Dickson, Bob Andrews, and Chuck Thoen. I am greatly indebted to the team at Iowa State University Press. I especially appreciate Jim Ice and Gretchen Van Houten for taking the time and effort to convince me to take on the project and to keep me motivated until its completion. To my editors, Lynne Bishop and Carla Tollefson: Thanks for demanding clarity, accuracy, and completeness.

xiv

Multi-site Pig Production

1. Introduction

Multi-site pig production refers to the rearing of the various age groups of swine at different locations or farmsteads. Tom Alexander’s (Figure 1.1) 1979 discovery that the separation of naturally farrowed piglets away from their mothers at weaning would exclude infectious agents led to a profound development in multi-site rearing technique. Tom coined the term medicated early weaning (MEW) for his discovery because he weaned the pigs early, with heavy medication, into an isolated location away from all other pigs. Based on studies whereby Tom’s approach was modified (and now is referred to as isowean), I proposed in 1987 that entire new pig farms be constructed where the three stages of production would be separated and located on three isolated sites or locations.

Figure 1.1 Dr. Tom Alexander, originator of MEW, is a lecturer in the Department of Clinical Veterinary Medicine, University of Cambridge, Cambridge, England. He has consulted for PIC for over 30 years. Dr. Alexander’s contributions to pig rearing include principles of disease control and eradication, etiologic investigations on swine dysentery, and mechanisms of disease causation by Streptococcus suis type 2.

3

Multi-site Pig Production

Table 1.1 The 50 Largest Producers of Pork in the United States in 1998 Name of Operation

Murphy Family Farms Carrol’s Foods Continental Grain Company Smithfield Foods Seaboard Corporation Prestage Farms Tyson Foods Cargill DeKalb Swine Breeders Iowa Select Farms Purina Mills (Koch) Goldsboro Hog Farm The Hanor Company Land O’Lakes Heartland Pork Enterprises Farmland Industries/Alliance Pipestone System/Hawkeye Christensen Farms and Feedlots Sand Systems Bell Farms National Farms Progressive Swine Technologies Clougherty Packing Company D & D Farms Holden Farms Hostetter Management Company Lundy Packing PIC International Group, USA Texas Farms Triple Edge Pork Vall Hastings Pork/MPI Farms J. C. Howard Farms DeCoster Farms of Iowa Coharie Farms Gold Kist Hog Slat Oakville Feed and Grain Hitch Pork Production J & K Farms Wakefield Pork Consolidated Nutrition Garland Farm Supply Swine Graphics Enterprises Sand Systems Newsham Hybrids, USA Western Pork Production Corp.

Headquarters

Number of Sows

Rose Hill, North Carolina Warsaw, North Carolina New York, New York Smithfield, Virginia Shawnee Mission, Kansas Clinton, North Carolina Springdale, Arkansas Minneapolis, Minnesota DeKalb, Illinois Iowa Falls, Iowa St. Louis, Missouri Goldsboro, North Carolina Spring Green, Wisconsin Minneapolis, Minnesota Alden, Iowa Kansas City, Missouri Pipestone, Minnesota Sleepy Eye, Minnesota Columbus, Nebraska Wahpeton, North Dakota Kansas City, Missouri Columbus, Nebraska Los Angeles, California Pierre, South Dakota Northfield, Minnesota Lititz, Pennsylvania Clinton, North Carolina Franklin, Kentucky Perryton, Texas Chandlerville, Illinois Texhoma, Oklahoma Hastings, Nebraska Deep Run, North Carolina Clarion, Iowa Clinton, North Carolina Atlanta, Georgia Newton Grove, North Carolina Oakville, Iowa Guymon, Oklahoma Harrells, North Carolina Gaylord, Minnesota Omaha, Nebraska Garland, North Carolina Webster City, Iowa Farmville, North Carolina Colorado Springs, Colorado Yuma, Colorado

337,000 183,000 162,000 152,000 125,000 125,000 123,500 120,000 97,000 90,000 75,000 64,000 64,000 63,700 61,000 48,500 46,800 44,000 43,000 41,000 34,000 27,500 23,000 22,000 22,000 20,000 20,000 20,000 20,000 20,000 20,000 19,400 19,000 18,200 17,400 16,500 16,000 16,000 15,000 15,000 15,000 14,000 14,000 14,000 14,000 13,500 13,000

4

1. Introduction

Table 1.1 continued Name of Operation

Neuhoff Farms Esbenshade Mills/Hershey Ag N. G. Purvis Farms

Headquarters

Richland, North Carolina Mt. Joy, Pennsylvania Robbins, North Carolina

Number of Sows

12,000 11,500 11,000 Total: 2,599,000

Source: Betsy Freese, Successful Farming, October 1998

Multi-site pig-rearing is not a new form of production: extensive outdoor systems have been perfected in the United Kingdom and the production of 8- to 10-week-old feeder pigs (40–50 pounds body weight) occurs in most swine-rearing countries. But the multisite rearing initiated in the United States in 1988 on a newly constructed 2000-sow farm where the three main stages of pig production were placed on three separate sites was an entirely new concept. This was the first farm ever constructed specifically for the separation of recently weaned pigs away from the adult swine population. In a 1995 study by the National Animal Health Monitoring System (NAHMS) of the U.S. Department of Agriculture, it was found that 60% of U.S. pork producers with over a 10,000-head inventory were using isowean technology (moving piglets from the farrowing phase to a separate-site nursery). In 1998, the total number of sows of the top 50 U.S. producers (Table 1.1) had increased by 500,000 sows. These sows were all placed in multi-site isowean production systems. Prior to 1987, no farm in the world was built in this manner for the purpose of excluding disease. This book is about this new era of pork production and why and how modern-day multi-site systems evolved. Both the advantages and disadvantages of this approach will be discussed.

Historical Perspective Pigs of all age groups (suckling pigs through adults) were usually placed either in outside pens or within buildings in close proximity to one another. Beginning around 1950, pigs began to be reared more in confined buildings and the various stages of production became more defined: breeding, gestation, farrowing, lactation, pre-nursery, nursery, grower, and finisher. Some farmers totally confined the pigs in buildings, while others used a combination of dirt lots and buildings (semi-confined). The phrase farrow-to-finish operation was used to describe farms situated on one site that were associated with the farmstead along with the residence and buildings housing other livestock. The “feeder-pig” industry that evolved in most swine-rearing countries during the 20th century was based on rearing the pig to slaughter weight on a farm or site different than the one on which it had been farrowed, or born. Farrow-to-feeder pig farms weaned the pigs into a pre-nursery or nursery. This type of operation usually sold the pigs (at 30–50 pounds body weight and 6–10 weeks of age) to another individual, who placed them in a grower/finisher building or in open dirt lots. 5

Multi-site Pig Production

When farmers had a grower/finisher building separate from the farrow-to-feeder pig facilities, the operations were called two-site farms (now referred to as traditional two-site production). Sometimes, the grower/finisher building could only “finish” a portion of the pigs reared at the farrow-to-feeder pig facility. Feeder pigs often originated from many different (multiple) sources. Prior to 1988, both finisher pigs and breeding stock were reared either on one-site farrow-to-finish or on traditional two-site production systems.

Breeding Stock Production on One-site and Traditional Two-site Farms Until the mid-1970s, boars were almost the exclusive means of transfer of genes among farms in the United States. Purebred breeders would supply boars (rather than both boars and gilts) to slaughter-pig and feeder-pig producers, who in turn would save back their own replacement gilts. Beginning in the 1960s in the United Kingdom and about 10 years later in the United States, the pyramid system of producing both gilt and boar breeding stock originated; it has been replacing traditional purebred breeding ever since. Breeding stock companies, such as DeKalb, Kleen Lean, and PIC, were the first in the United States to promote and utilize the pyramid system, which placed a nucleus farm at the apex for development of superior genetic lines. (See Chapter 8, “Production Pyramids.”) Pyramid-style breeders created a convincing argument that genetic improvement could be made faster in the nucleus herd at the apex of the pyramid than by the producer of slaughter pigs simply utilizing rotational-cross boars. (With rotational-cross boars, commercial producers usually supplied their own replacement females for the breeding herd.) Thus, the customers were enticed into purchasing both boars and gilts from the pyramid breeder rather than simply boars from the purebred breeder. Interestingly, boars from purebred breeders were relatively free of disease due to age immunity. (See Chapter 4, “Herd Immunity.”) Since very few animals needed to be introduced into a commercial herd each year (only a few boars to maximize rotational-cross heterosis), the chance of disease introduction was quite limited. By contrast, customers of pyramid breeders needed their entire boar and gilt replacements supplied to them annually (30%–40% of the herd each year). The introduction of such high numbers of replacement animals per year increased the chance of disease introduction. In areas of high pig density, diseases are transmitted among farms quite readily. The disease status of pigs was very important because breeders, especially, could spread infectious agents to other farms by the sale of seedstock. For this reason, methods were developed to establish breeding herds with high–health status pigs. Considerable attention also has been given to development methods to limit the occurrence and transmission of disease in pig farms. George Young and Norman Underdahl (first at the Hormel Institute in Albert Lea, Minnesota, and subsequently in Lincoln, Nebraska) originated the specific pathogen–free (SPF) concept for disease control in the early 1950s. This idea spread rapidly around the world. It was adopted most successfully in Switzerland, Sweden, and Denmark, and these three countries still have a majority of their producers enrolled in the SPF program. Purebred breeders and breeding stock companies continue to use SPF techniques (surgical derivation and isolator rearing of colostrum-deprived piglets) to establish high–health status 6

1. Introduction

herds, but producers in all countries have had difficulty in keeping such herds free of pathogens on a long-term continual basis. Aujeszky’s disease (pseudorabies virus) was financially devastating to the seedstock business in the mid-1980s in the United States, United Kingdom, and some European countries. At that time, if a seedstock producer’s farm became infected with pseudorabies virus (PRV), the farmer had no choice but to stop selling breeding stock. If the farmer wished to continue producing breeding stock, total depopulation and repopulation with PRVfree stock was the only alternative.

The First Three-site Farm Because of the desire to avoid total depopulation if and when PRV infection occurred, I hypothesized that placing a farrow-to-finish farm on three sites would negate the need for total depopulation of the herd should PRV occur. Thus, the concept of three-site production originated, where the weaned pigs (3 to 10 weeks of age) were reared on a separate site from both the adult population and the older finisher pigs. Until then, weaned pigs were raised in close proximity to the adult breeding-age swine on farms. In 1988, CRB, the first modern-day multi-site pig production facility (a three-site isowean farm) in the world was constructed near Columbus, Nebraska, by Chuck Sand (Figure 1.2). It was built specifically to produce high–health status breeding stock to

Figure 1.2 Chuck Sand, builder and owner of CRB, is founder and president of Sand Livestock Systems and chairman of Sand Systems, Inc., of Columbus, Nebraska. His company was a leader in the evolution to totalconfinement pig rearing in the United States. In addition, Sand Construction has built multi-site pig production systems in many countries of the world, including the People’s Republic of China. (Photo reprinted by permission from the Omaha World Herald, Omaha, Nebraska)

7

Multi-site Pig Production

A. B.

Figure 1.3 Three-site production. A. Diagram of a three-site system. B. Aerial photograph of site 1 at CRB farm, near Columbus, Nebraska, consisting of two farrow-to-wean buildings with 1000-sow capacity each. C. Aerial photograph of site 2 at CRB consisting of one nursery building. D. Aerial photograph of site 3 at CRB consisting of 5 grower buildings and 11 finisher buildings.

decrease the financial risk associated with infectious diseases. On this farm, the various age groups (stages of production) were placed on three geographic sites separated from one another by over 2 miles. The breeding, gestation, and farrowing stages (breeding production stage)1 were on site 1, the pre-nursery and nursery stages (nursery production stage)1 on site 2, and the grower and finishing stages (finisher production stage)1 on site 3 (Figure 1.3). 1. The National Pork Producers Council Production and Financial Task Force has recommended the use of these terms to indicate the three stages of pork production.

8

1. Introduction

C. D.

Although the farm was stocked with PRV-negative stock, the sows in site 1 became infected with PRV within 1 year. Vaccination of the sows at site 1 and depopulation of the nursery successfully eliminated the virus from the system. The pigs in the finisher never acquired PRV infection. Producers and industry leaders in many parts of the world quickly perceived this new approach to multi-site production was a way to avoid healthstatus deterioration associated with one-site and traditional two-site production systems and as a way to enhance pig performance and carcass quality. From 1989 through 1996, I have had personal involvement or knowledge of modernday multi-site farms being built either as modifications of existing structures or as new facilities in the United States (Nebraska, Colorado, Iowa, Oklahoma, North Carolina, 9

Multi-site Pig Production

Texas, Missouri, Minnesota, Illinois), Canada, Mexico, Brazil, Chile, Spain, Germany, Poland, Italy, Scotland, England, China, and France (see Tables 1.2 and 1.3).

Terminology Stages of Production. The three stages of production are the (1) breeding production stage, (2) nursery production stage, and (3) finisher production stage. Stage 1 (Breeding Production Stage). Production stage in which breeding females and boars are kept and managed for the purpose of producing weaned pigs. Breeding, Gestation, and Farrowing. The substages of breeding production that involve the adult females and males, including the mating (both by natural service and artificial insemination) and the gestating of sows. The farrowing substage also includes the farrowing and lactation of the young suckling piglets. Stage 2 (Nursery Production Stage). Production stage associated with nursery pigs. Pre-nursery. A substage of nursery production for rearing the young pig immediately after weaning. It is excluded from most pig farms. Nursery. A substage of nursery production for rearing the young pig either immediately after weaning or after the pre-nursery stage. The pigs are usually held in the nursery for 7 weeks. Stage 3 (Finisher Production Stage). Production stage associated with finisher pigs. Grower. A substage of finisher production for rearing the pig immediately after the nursery. It is excluded from most pig farms. Finisher. A substage of finisher production for rearing the pig either immediately after the nursery stage or after the growing stage until it is either slaughtered for meat consumption or used as a breeding female or male. Site. A site number indicates the placement for the various stages of production and the type of single- or multi-site production system. A site most often refers to the tier level of the production system. Although site sometimes is used to indicate location within a tier level, locus is the preferred term for location within a tier. Locus or Loci. Loci indicate the number of geographic locations for each stage of production at each site. Single Locus. A stage of production is placed entirely on one geographic location. Multiple Loci. A stage of production is placed on more than one geographic location. Medicated Early Weaning (MEW) (Figure 1.4). Pregnant sows are farrowed in isolation in all-in/all-out farrowing rooms away from the source herd. At about 5 days of age, piglets are weaned into an isolated nursery on a separate site. At 6 to 10 weeks of age, the pigs are transferred to an isolated grower/finisher on a third site. Prior to farrowing and during lactation, sows are medicated against the specific bacteria that are to be eliminated. 10

1. Introduction

Figure 1.4 Medicated early weaning (MEW).

Figure 1.5 Isowean (modified MEW).

The piglets are medicated during suckling and for the first 10 days after weaning. Where appropriate, the sows can also be vaccinated 3–4 weeks prior to farrowing. This is the classical procedure for MEW, but several variations of it have been applied successfully. Isowean or Modified Medicated Early Weaning (MMEW) 2 (Figure 1.5). Similar to MEW except that the sows are farrowed in the source farm in the normal way rather than in an isolated farrowing house. Also, the weaning age is variable (from 5 to 21–28 days of age), depending on the infections to be eliminated. Other terms that have been used for

2. These terms were used in Chapter 72 of Diseases of Swine, 8th ed. (1999), but I have suggested their usage be discontinued (see “Recommendations for the Use of Certain Terms,” Chapter 9 of this book). When these terms are used in Chapter 1, they are followed [in brackets] by the term recommended in Chapter 9.

11

Multi-site Pig Production

isowean or MMEW or variations of it are segregated early weaning (SEW),2 segregated weaning,2 age-segregated rearing (ASR),2 and isolated weaning.2 The term isowean is often used more widely to cover any system involving segregated or isolated weaning, which is how it is used in this book. (See also Isowean Principle.) Isowean Principle. The principle that piglets remain free from most of the serious potential pathogens endemic in a herd until after weaning (when, in traditional systems, they are sequentially exposed to pathogens from older, growing pigs). Furthermore, the piglets are likely to remain free of these pathogens if they are raised in isolated groups away from their cohorts and other age groups. This principle is the basis on which modern-day multi-site pig production systems (with the first stage of production [breeding, gestation, and farrowing] on site 1) have been developed. One-site Production (Farrow-to-Finish). All three stages of production take place on site 1 (see Figure 2.1). Historically, this is the way pigs have been raised. Two-site Production Traditional Two Site. Two-site production where stages 1 and 2 are placed on site 1 at one at one or more loci, and stage 3 is placed on site 2 at one or more loci. Prior to 1989, this was the only type of two-site production system (see Figure 2.2). The Isowean Principle does not apply. Two-site Isowean. Two-site production where stage 1 is placed on site 1 at one or more loci, and both stages 2 and 3 are placed on site 2 at one or more loci (see Figures 2.13 and 2.14). There can be one or more buildings at each locus. The Isowean Principle applies between sites 1 and 2. Three-site Production. Each of the three stages of production are located on separate sites, which are referred to as sites 1, 2, and 3 respectively. At each site, there can be one or more loci. The Isowean Principle applies between sites 1 and 2. There can be one or more buildings at each locus (Figure 1.3). Three-site Isowean Production.2 Sometimes this is simply referred to as three-site production because it is understood that the Isowean Principle applies by definition. Three-site isowean production has often been used to mean placement of facilities on only one locus at each site. In that case, multiple-site isowean production2 has been used to mean placement of facilities on more than one locus at each site. Multiple-site Isowean Production.2 This term incorporates the advantages of all-in/allout production by site for stages 2 and 3 with the advantage of isowean. Each week’s weaning fills the nursery accommodation on one site, and each week’s emptying of a nursery site (7 weeks after filling) populates the grower/finisher accommodation of one site. The disadvantage of this system is that a large number of sows are required, often in the order of 12,000, and ideally >24,000. They can be in several different loci. A synonym for this type of production system is three-site production on multiple loci. Based on the nomenclature proposed in Chapter 9, this is a type of three-site production in which pigs are reared on multiple loci. 12

1. Introduction

Multiple-site Production.2 This term is sometimes used to mean multiple-site isowean production. Multi-site Pig Production. A blanket term to cover any arrangement of sites and loci, including all types of two- and three-site production systems. The Isowean Principle may or may not apply. Multi-site Isowean Production. A blanket term to cover any arrangement of sites that incorporates the Isowean Principle, including the various possible configurations for two- and three-site production. Isowean pigs may be from single or multiple sources. This kind of production also is referred to as modern-day multi-site production. Source of Pigs. In multi-site production, source refers to either the number of sources of isowean pigs originating from a breeding production stage or the number of sources of feeder pigs originating from nursery buildings. Single Source. The pigs originate only from one locus of production. Multi-source. The pigs originate from more than one loci of production. Nursery/Finish Building. Isowean pigs are placed in a finisher building equipped to provide adequate comfort, waterers, feeders, and pens for pigs ranging in age from 2 to 3 weeks through slaughter weight. Other terms that have been used for nursery/finish buildings are NurFin and wean-to-finish. All-in/All-out Pig Flow by Site, Locus, Building, or Room. Populating a site, locus, building, or room in one day with pregnant sows at term or with pigs of the same age. The site, locus, building, or room is depopulated completely at the appropriate time (usually 2–3 weeks of age for piglets nursing sows, 6–7 weeks later for nursery pigs, and