Polymorphism of the PrP prion protein gene in Polish Merino and Berrichone du Cher sheep

The study was conducted on ewes and rams of the Polish Merino and Berrichone du Cher breed in the Grotkowo flock (VVielkopolskie Voivodeship). The examined sheep were aged 1 year (152 female and 32 male Polish merino 220 female and 68 male Berrichone du Cher). All animals were subjected to the identification of the PrP prion protein gene. Based on the study a highly significant effect of breed and no significant effect of sex within the breed on the frequency of alleles and genotypes of classical scrapie in Polish Merino and Berrichone du Cher were found. In Berrichone du Cher five alleles (ARR,ARQ,AHQ,ARQ, VRQ) and in Polish Merino six alleles were found (ARR, ARQ, AHQ, ARQ, VRR, VRQ). What is important, the VRR allele was detected for the first time in a Polish sheep population. 9 genotypes of scrapie in Polish Merino and 7 in Berrichone du Cher were identified. Very high frequencies of the genotype ARR/ARR and ARR/ARQ in Polish Merino and high frequencies of ARR/ARR genotype in Berrichone du Cher were found at a very low level of genotypes, which coded value in both breeds. The assumptions of breeding work involving the elimination of the presence of animals encoding valine at codon 136 and the introduction of rams to the population containing ARR allele in their genotype was associated with increased frequency of occurrence in the population of ARR/ARR and ARR allele. That indicates the advisability of such breeding work which should be recommended for the genetic improvement of other breeds in the national population of sheep.