Genomics and disease resistance studies in livestock

- Factors influencing disease genetics studies are reviewed.
- Results are presented in detail for a viral disease and a bacterial disease.
- Breeding for resistance is often possible, but not always appropriate or necessary.
- Effective studies combine disease biology, epidemiology and genetics.
- Rate limiting step is likely to be provision of phenotypes rather than genotypes.

This paper considers the application of genetic and genomic techniques to disease resistance, the interpretation of data arising from such studies and the utilisation of the research outcomes to breed animals for enhanced resistance. Resistance and tolerance are defined and contrasted, factors affecting the analysis and interpretation of field data presented, and appropriate experimental designs discussed. These general principles are then applied to two detailed case studies, infectious pancreatic necrosis in Atlantic salmon and bovine tuberculosis in dairy cattle, and the lessons learnt are considered in detail. It is concluded that the rate limiting step in disease genetic studies will generally be provision of adequate phenotypic data, and its interpretation, rather than the genomic resources. Lastly, the importance of cross-disciplinary dialogue between the animal health and animal genetics communities is stressed.