Polymorphism of the CSN3 gene and its relationship with dairy productivity of cows

The analysis of polymorphism of markers of milk productivity is significant and relevant. The purpose of the research is to analyze the frequency of occurrence of desirable alleles of the kappa-casein gene in cows and their association with the level of dairy productivity in the Omsk region. The total number of cows in the sample was 200. Biomaterial was selected from the studied cow population in order to isolate DNA and determine animal genotypes by the kappa casein gene (CSN3). The groups were formed taking into account the breed of animals. Animals with the AB genotype of the CSN3 gene are found in the population with different frequencies, from 0.12 to 0.48. The results of determining the genotypes of cows of black-mottled and red steppe breeds showed that the majority of animals have the AA genotype, where the frequency of occurrence is 84...48%. The minimum number of individuals from the sample was identified by the BB genotype with a distribution of 0...12%. In the dairy cattle population of the Omsk region, the maximum frequency of occurrence of allelic variants of the CSN3 gene locus was determined in the group of black-and-white cows with the AA genotype and is 68%. The B allele is less common. Only 2% of black-and-white cows carry the allele B of the CSN3 gene. There is a mo-derate negative relationship between the allele B of the CSN3 gene and milk yield for lactation. The correlation coefficient between the presences of the B allele in the genotype in the group of black-and-white cows was -0.52, which causes a decrease in milk yield of cows with the A/B or A/B genotype. The mass fraction of milk fat and the presence of the allele in the CSN3 gene are also in a weak negative correlation. The correlation coefficient varies depending on the breed from -0.21 to -0.18. A part of the population has the genetic potential to synthesize milk with a high protein content and high cheese suitability. It is necessary to intensively introduce DNA analysis into the breeding process in order to identify optimal genotypes and use them in cattle breeding.