MOLECULAR GENETIC ANALYSIS OF UKRAINIAN GRAY CATTLE BY THE BETA-CASEIN GENE

Abstract

The article describes the results of the study of the beta-casein gene in populations of the Gray Ukrainian breed of cows, which is associated with milk productivity. The most common variants of β-casein in dairy cattle are A1 and A2. The CSN2A1 variant causes serious abnormalities in the human body, namely a number of pathologi-cal disorders in the work of the intestines, coronary heart disease, diabetes, and autism in chil-dren. The analysis of scientific publications shows that the beta-casein gene (CSN2) has not been studied in aboriginal breeds of cattle of Ukraine, which are carriers of specific gene com-plexes and most rare alleles. We conducted molecular genetic studies of polymorphism at the beta-casein gene locus in populations of the aboriginal gray Ukrainian breed from the main breeders of this breed in Ukraine. Genomic DNA isolated from the whole blood of 173 animals was amplified using primers that were created on the basis of the sequences of the CSN2 gene of cattle. The amplified fragment of CSN2 with a length of 121 bp. treated with DdeI restriction enzyme. All three genotypes were detected in the studied populations: homozygous CSN2A1A1, CSN2A2A2 and heterozygous CSN2A1A2. The analysis of the results showed that carriers of the CSN2A1A2 heterozygous genotype predominate in the cows of the Markeevo State Farm (94.2%), the CSN2A2A2 genotype was absent. The results of genotyping of "Polyvanivka" SE revealed that 20% of animals are carriers of the CSN2A2A2 genotype, which produce A2 beta-casein milk. The CSN2A1A2 genotype prevailed, which was determined in 53% of cows. In general, the studied breed shows a fairly high level of the "desired" allele A2 – 0.468, when uncoupling, β-casoformin 7 is not produced.