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EXECUTIVE SUMMARY SLP LINK Project LK0623 Quantifying generalised immunity in genetically diverse pigs Start date: 01/12/1998 Partners: Sponsor: End date: 30/11/2000 Cotswold Pig Development Company Ltd JSR Healthbred Ltd (this & above now part of JSR Genetics) Meat & Livestock Commission Newsham Hybrid Pigs Ltd (now part of JSR Genetics) Pig Improvement Company (now Sygen International) Rattlerow Farms Roslin Institute (Edinburgh) Ministry of Agriculture, Fisheries & Food (now Defra) 1 Healthier animals benefit everyone: animal welfare and food safety are increased and production costs are reduced. This project identified immunity measurements that may be used to identify healthier and more productive pigs. Animal health issues are becoming increasingly important to all sectors of livestock production, including the pig industry. This is due to: Industry requirements to improve animal productivity, health and welfare Public concerns regarding food quality and safety. In its breeding programmes, the British pig industry has concentrated on selecting animals for production traits, such as growth rate, carcass characteristics and litter size. Disease resistance is also a very desirable target for selection, but often there are difficulties in measuring resistance to specific diseases (animals may need to be challenged with the disease) and the lack of tools to select for improved general resistance or immunity. If the difficulties associated with measuring resistance can be overcome, improving disease resistance would be very beneficial. In addition to improving public perception, benefits would include reductions in costs associated with sick animals, lessening the impact of acute infections and, in the case of subclinical or chronic infections, healthier and more productive pigs. Additionally, healthier pigs would require fewer antibiotics. Improving Disease Resistance and Generalised Immunity There are several possible approaches to improving disease resistance. If there is a ubiquitous disease of particular importance, it may be possible to select directly for those animals that show resistance to this disease. But, animal health issues may be often apparent even when there is no obvious disease to target. In this instance, it may be more appropriate to concentrate on aspects of animals’ immune responses. The aim would be to select animals with appropriate immune responses to a variety of disease challenges. This concept is known as generalised immunity. Although there is no guarantee that improving generalised immunity will make animals more resistant to specific diseases, in a production environment it may result 2 in healthier and more productive animals. This has indeed previously been demonstrated in pigs selected on an index combining several immunological parameters. Thus, generalised immunity would appear to be an appropriate means of including health-type traits into conventional breeding programmes. The Project The project investigated the use of generalised immunity, using measurements that were components of the innate immune response – the non-specific defence mechanism against pathogens. Comparisons were made between divergent breeds such as the Large White and Meishan, and selected lines within the Large White breed which differed in productivity. The main findings of the project were: Several innate immunity measures were identified that were repeatable, stable across time, and suitable for scaling up to the needs of a commercial breeding programme Considerable apparent genetic variation was observed, between breeds and between lines, in nearly all innate immunity traits Several measurements, including the proportions or numbers of B cells, monocytes and NK cells, were correlated with the performance of the same animal Several measurements, including white blood cell number and acute phase protein response, differed significantly between lines previously selected for performance. This suggests a genetic correlation between these traits and performance in animals facing subclinical challenges. A ‘generalised innate immunity’ index was derived: selection on this index should lead to enhanced immunity and enhanced performance in progeny of selected animals. Outcomes The results of this project suggested a means of improving the immune response, health and performance of pigs performing under commercial conditions. Patent protection has been sought for this technique. Currently, the extant breeding 3 companies from the original consortium are participating in a LINK project designed to test and refine this technique. If successful, these measurements can be incorporated into the breeding programmes of these commercial breeding companies. The end product will be healthier pigs better able to meet the challenges of modern farming systems. CONTACT Professor Stephen Bishop or Dr Liz Glass Roslin Institute Roslin Midlothian Edinburgh EH25 9PS Tel: 0131 527 4200 Fax: 01379 388272 [email protected] [email protected] 4