Abstract
This research work describes the polymorphism of kappa-casein (CSN3), beta-lactoglobulin (LGB) and prolactin (bPRL) in cows of Simmental breed at farm «Galitskoye» in Pavlodar region. Frequency distribution of alleles and genotypes of the studied genes were conducted. It is found that the occurrence frequency of A and B alleles according to kappa-casein (CSN3) gene was 0,51 and 0,49, according to beta-lactoglobulin (LGB) had 0,36 and 0,64, prolactin (bPRL) reached 0,68 and 0,32. Results of the study about genes’ influence on milk production showed that milk yield per lactation of cows in the group of animals with kappa-casein genotype was AA – 5356 kg, AB – 5387 kg, ВВ – 5517 kg. The study noted the superiority of AA alleles of beta-lactoglobulin genotypes and prolactin on the studied indices, the advantage in milk yield, protein content and milk fat according to kappa-casein genotype was observed in cows with BB genotype. Research results stated that cows with BB genotype according to kappa- casein and AA alleles were more productive and had the highest yield of milk protein according to beta-lactoglobulin and prolactin. Keywords: Simmental breed, milk production, gene expression, DNA – polymorphism, candidate genes, kappa-casein gene (CSN3), beta-lactoglobulin (LGB), prolactin (bPRL).