Genomic tools for examining genetic variation of health traits

Animal health is a complex trait with both genetic and non-genetic influences. Considering disease resistance specifically, animals will vary in their genetic predisposition toward resistance or susceptibility to disease, and knowing which genes contribute to innate susceptibility or resistance would greatly facilitate genetic selection. The alternative, application of classical selection programs, is complicated by varying contributions of management and environment to disease exposure and ambiguity in diagnosis of disease phenotype. Disease resistance is an excellent example of a trait where gene mapping and marker-assisted selection holds particular promise. The objective of this paper is to briefly describe some of the tools and approaches used to map genes, such as genes for disease resistance. Examples of the application of this approach to mapping genes for disease resistance/susceptibility in cattle will also be described.