POLYMORPHISM OF THE KAPPA-CASEIN GENE IN THE DAIRY CATTLE POPULATION OF THE OMSK REGION

The aim of research is to study the polymorphism of the kappa-casein gene in the dairy cattle population of the Omsk Region. The object was the herd of cows (n = 400) of the Black-and-White breed, which constituted selection groups in the breeding farms of the Omsk Region. Genetic analysis of the samples was carried out using PCR diagnostics of each DNA sample. For the kappa-casein gene in the studied breed, the frequency of heterozygotes was 0.40. The values of the other two genotypes varied from 0.12 to 0.48. In the population of dairy cattle of the Black-and-White breed, the B/B genotype was found with a frequency of 0.12. The main part of the herd – 52 % of cows carry the allele associated with milk protein content. Animals with the A/A genotype exceeded their peers in milk yield by 503 kg, or 8.05 %, and were distinguished by maximum milk production (P < 0.05). Cows with the B/B genotype had 6242 kg of milk per lactation, which is 345 kg, or 5.53 %, less than in the heterozygote group. The mass fraction of milk protein in the group of cows with the B/B genotype was 3.84 %, which is 0.69 % (P < 0.05) higher than in cows with the A/A genotype, and 0.63 % higher than in the group of heterozygotes with the A/B genotype. The gene pool of the population of black-and-white dairy cattle bred in the Omsk Region is distinguished by a variety of alleles of the kappa-casein gene, but is in equilibrium. Thus, B-alleles of the kappa-casein gene are associated with an increased content of milk protein; the selection of animals according to this criterion will contribute to an increase in the mass fraction of milk protein.