Polymorphism of the beta-casein gene in dairy breeds of cattle

The polymorphism of the beta-casein gene (CSN2) in dairy cattle of the Russian Federation was assessed. The Kholmogorskaya, Yaroslavskaya, Red-and-White, Holstein and Brown Swiss breeds of a total of 1,447 heads were studied. 2894 DNA analyses were performed by PCR. To determine the A1 and A2 beta-casein alleles, an allele-specific variant of the PCR method (AS-PCR) was used. In the studied breeds, the CSN2 A1A2 genotype prevailed 40-47%, except for the brown Schwyz. The frequency of the most favorable in terms of dietary properties of milk with the CSN2A2A2 genotype in the brown Schwyz breed herd was 83% of animals, in Kholmogorskaya 29%, in the red-mottled breed 30%, in Yaroslavl 19%. The desired CSN2A2 allele in the Brown Schwyz breed herd was the highest frequency of 0.917. The least CSN2A2 allele was observed in the studied herd of the Yaroslavl breed.