Influence of kappa-casein genotype on milk yield of cows and on culling of cows

Abstract

For production of milk the breeds of highly productive dairy cows of domestic and foreign selection are used. These breeds include the Black-and-white mottled breed, which makes up more than 51% of the total cattle herd in Russian Federation, and the Holstein breed, which share is more than 15% and is constantly increasing. It has been established that cows with different kappa-casein genotypes differ in usability of their milk for cheese production. The research of influence of kappa-casein genotype on milk yield capabilities of cows and the reasons for culling of cows is relevant and of interest nowadays. The biggest share of the herd consists of cows with AA genotype, and the least share, 3.8%, consists of the most favorable BB genotype cows. These cows feature higher milk yield. Though there was no significant difference between the milk yield of cows with genotype BB and genotypes AA and AB, but a tendency for BB genotype superiority was clearly observed. The higher milk yield determines a higher yield of nutrients with milk. The group with the AB kappa-casein genotype accounted for a greater share of culled cows in the first lactation period. The lower rejection rate was recorded in the group of BB genotype cows.