GENOMIC APPROACHES TO THE IMPROVEMENT OF DISEASE RESISTANCE IN FARM-ANIMALS

As a result of the difficulties in improving disease resistance in far m animals by traditional phenotype selection, the achievement of such improvement is one of the most important applications of genome resear ch. The major hurdle to this important goal is the collection of infor mative disease records to enable the segregation of disease resistance loci (DRL) to be traced in pedigrees. This paper reviews the principl es for DRL identification by association analyses or by linkage analys es. Once linkage has been established, the location of the DRL may be further refined, a process which may eventually lead to the molecular characterisation of the causative gene(s) and mutation(s). A reliable map assignment of a DRL is sufficient for the practical utilisation of this knowledge, since the inheritance of the DRL can be traced by fla nking markers. Marker-assisted selection concerns the use of linked ma rkers for selection within populations, while marker-assisted introgre ssion is used if DRL alleles are introgressed from a donor (resource) population.