Breeding for resistance or tolerance to coccidia in broiler chickens

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Broiler chickens are the domestic species most intensively selected for production and Eimeria (coccidia) infections are the most pervasive challenge to their health and productivity, estimated to cost the UK industry > £80m per annum. The various method of its control are either not effective or are threatened by long term sustainability, such as the development of coccidian resistance to drugs The issue of controlling through genetic selection for diseases that cause such substantial production losses remains unresolved, although it is an attractive possibility. The breeder has the choice of exploiting two host strategies: resistance to (the ability to limit pathogen replication) and tolerance of (the ability to limit the impact on host productivity or health). The relative contribution of these two strategies to infection outcomes, is poorly understood. Understanding has been hampered by statistical methods to analyse the genetic basis of tolerance at individual level and by considering it as a static as opposed to a dynamic trait. We recently developed a methodology that overcomes these limitations, by considering individual infection dynamic trajectories portraying simultaneously changes in infection severity and performance. The aim of this project is to apply this methodology to Eimeria infections of broilers to determine: 1) whether there is genetic variation in tolerance to Eimeria; 2) how broiler chicken genotypes selected for different production intensities map onto distinct trajectory types; 3) whether these genotypes rank similarly in terms of resistance and tolerance to infection and 4) whether this ranking is affected by different coccidian infections regulated by different immune responses.The proposal falls entirely under the remit of BBSRC Strategic Research Priority 1: Agriculture and Food Security. It is consistent with BBSRC aim to 'support research in areas that have profound implications for food security and food safety, such as animal health and welfare, and genetics and genomics for improved production and disease resistance'.The studentship falls within the remit of the animal Health priority of BBSRC, which aims to to support fundamental and strategic research leading to the development of intervention strategies for combating endemic diseases that reduce the health and welfare of either animals farmed for food production in the UK (and where appropriate, in the international context) or other domesticated animals of importance to the UK economy. The student will be trained in a number of disciplines that are of relevance to food security and food safety (animal breeding and genetics, parasitology, animal science, statistical techniques), and by doing so it will advance the BBSRC aim of 'ensuring that the UK skills base has appropriate critical mass and specialist research expertise to support these disciplines'.