Milk productivity of black-and-white and Kholmogory cows with different genotypes of kappa-casein

Abstract

The influence of genotypes for kappa-casein gene on the main indicators of milk productivity in the 1st and 3rd lactation in black-and-white and Kholmogory cows was studied. The genotyping of cows for the CSN3 gene was carried out by the method of DNA diagnostics. Cows of the black-and-white breed with genotype CSN3 BB surpass the group with genotype CSN3 AA and CSN3 AB in the 1st lactation in milk yield by 166-218 and in milk fat yield by 4.9-8.7 kg; for the 3rd lactation 188-298 kg and 7.7-10.2 kg, respectively. At the same time the difference is significant in terms of the mass fraction of protein in milk by 0.06-0.15% (Р<0.05-0.001) and 0.11-0.15% (Р<0.001) and in the yield of milk protein (Р<0.05) 8.3-14.2 kg and 14.8-16.1 kg (P<0.05). Kholmogory cows have a similar advantage for cattle with genotypes CSN3 AA and CSN3 AB in terms of milk productivity with a significant excess in the mass fraction of protein in milk for the 1st lactation by 0.07-0.14% (Р<0.05-0.001), for the 3rd lactation by 0.08-0.11% (Р<0.05-0.001). Consequently, the black-and-white and Kholmogory breeds have approximately the same level of superiority of cows homozygous for B allele CSN3 over their herdmates.