Genetic markers of milk proteins and their influence on milk protein content and chemical composition of milk in Holstein, Jersey and Ayrshire breeds of cows

The paper examines the influence of genetic markers of milk proteins on the protein content and economic efficiency of milk in cows of three leading breeds: Holstein, Jersey and Ayrshire. The results of the study show that the Jersey breed is able to provide genetic advantages of protein in milk with a high frequency of favorable alleles (CSN3 BB and CSN2 A2A2). It was determined that the Holstein breed, on the contrary, is characterized by high milk yield, but low protein content, which determines the prevalence of the CSN3 AA and CSN2 A1A1 genotypes. It was found that the Ayrshire breed occupies an intermediate position, demonstrating balance. The study also showed that the complex genotype CSN3 BB / CSN2 A2A2 / BLG BB provides the maximum content of protein and fat in milk. It was found that based on the obtained data, breeding work aimed at increasing the proportion of favorable genotypes in the Holstein and Ayrshire breeds for determining the protein content of milk is recommended. It was found that optimization of the genetic composition will improve the technological properties of milk and its ability to be processed. It was determined that in order to increase the protein content of milk, breeding improvement of the Holstein and Ayrshire breeds aimed at increasing the proportion of favorable alleles (CSN3 B and CSN2 A2) is recommended. This will increase the technological value of milk without significant losses in productivity. It was found that investing in breeding programs is justified from an economic point of view, since it allows to significantly increase the price of milk and increase the net profit of farmers and processing enterprises. The purpose of the study is to analyze the distribution of genotypes by the main markers of milk proteins in the Holstein, Jersey and Ayrshire breeds, their effect on the content of protein, fat and other components, as well as to identify genetically promising combinations for breeding work.