At a time of high public awareness of food safety issues, particularly with respect to transmissable encephalopathies, and a government policy to eradicate scrapie, there is increasing pressure for breeders to select for scrapie resistance in sheep. Genetic variation has been identified at the PrP locus that confers differing degrees of susceptibility to scrapie. In the Suffolk breed this variation is confined to amino acid variations at codon 171, resulting in two alleles R and Q. Animals with the genotype RR and RQ show a greater degree of resistance to scrapie than animals with genotype QQ (Hunter, Moore, Hosie, Dingwall and Greig, 1997).
Genotyping of pedigree animals has now become routine for many breeders and RR animals are favoured. It is, however, unknown whether there is a relationship between PrP genotype and performance traits. The objective of this study was to analyse the relationship between PrP genotype at codon 171 and the performance traits included in the Lean Index (Simm and Dingwall, 1989), which is used for selection in the Suffolk breed.