Download Quantifying Generalised Immunity in Genetically Diverse Pigs

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)
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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
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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
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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]
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