Kappa-casein as one of the factors affecting productive qualities of cows

Nowadays genetic research methods are becoming increasingly important in animal science. The aim of the work is to analyze the effect of kappa-casein modifications on the productive properties of Holstein cows bred in the farms of the Sverdlovsk region. The tests have been carried out in two breeding organizations of the Sverdlovsk region. The animals have been genetically typed by polymerase chain reaction method with subsequent polymorphism of the restriction fragment lengths. The results have been calculated using statistical processing. The polymorphic variants of the kappa-casein gene have been analyzed in an experimental herd of the Ural type cows. The cows with the AA kappa-casein modification have been of the highest frequency of occurrence - 60%, and the cows with the BB genotype have been of the lowest frequency of occurrence - 8%. Theoretically, the expected genotype frequency is lower than the actually obtained frequency by 2% and 4%. The evaluation criterion χ2 empirical - 2.6 is determined, indicating the gene balance maintenance in the studied population. Indicators of milk productivity have been evaluated for the period of 305 lactation days. The first farm animals with BB kappa-casein modification as well as the second farm animals with AB modification have shown the best results in milk yield, protein content in milk, milk fat and protein yield. The cows with homozygous AA genotype have shown a higher indicator in the mass fraction of milk fat with an unreliable difference between the groups. The conducted tests have showed the genotype influence of kappa-casein on the productive qualities of the experimental animals.