Characteristics of kappa-casein gene polymorphism in cows of Swiss breed and their productive qualities at a large dairy

Abstract

Kappa-casein is a fraction of the main milk protein, which determines the technological properties of milk and the quality of dairy products, especially cheese and fermented milk products. The study tested the distribution of kappa-casein gene genotype polymorphism (CSN3) in mothers and daughters of the Swiss breed cows, taking into account their milk productivity qualities. The study was performed on 111 cows of the Swiss breed on a large dairy. The observation group I included 51 cow-mothers of the Swiss breed; group II – 60 cow-daughters of the Swiss breed. In a study of the polymorphism of the kappa-casein gene in cow-mothers and cow-daughters of the Swiss breed, the dominance of allele B (0.73 and 0.70) was found, which was registered more than two times more often than allele A. The incidence of genotypes AA – AB – BB in cow-mothers of the Swiss breed was as follows: 5.9% – 43.1% – 51.0% with indicators of observed heterozygosity 0.43 and expected heterozygosity 0.40. In cow-daughters of the Swiss breed the frequency of the BB genotype was the same, but, genotype АА was registered almost twice as often, with lower indicators of observed heterozygosity and smaller increases of indicators of expected heterozygosity than in cow-mothers. Cow-mothers of the Swiss breed with the AA genotype, in comparison with the AB genotypes, had higher milk yields during lactation (by 43%), fat production (by 86.9%), ratio of fat to protein (by 40.5%). Also note, the cow-mothers of the Swiss breed with the AA genotype, in comparison with the BB genotypes, had reliably high rates of fat to protein (by 35.8%) and only a trend to higher fat production; fat and protein. The production of fat in dairy cows-daughters with the BB genotype was higher than with the AA genotype, but only at the level of tendency. The correlation analysis showed that the AA genotype of the kappa-casein gene in cow-mothers of the Swiss breed was associated with the duration of lactation, indicators of milk yield during lactation, fat production, fat content and protein in milk with registration of reliable and positive coefficients of correlation. The genotypes in cow-daughters did not have a reliable correlation with the duration of lactation and fat or protein content in milk. The results of the kappa-casein gene polymorphism study indicated that the AA genotype of cow-mothers of the Swiss breed was associated with higher productive milk qualities which should be taken into account when forming a highly productive herd of cattle of the Swiss breed under intensiveoperative technology at a large-scale dairy unit.

Keywords

• brown swiss cattle; alleles; genotypes aa, ab, bb of kappa-casein; milk yield; fat; protein.