Inheritance of allelic variants of the kappa-casein gene by cows

The inheritance of allelic variants of the kappa-casein gene from bulls with different genotypes and their influence on the milk production of daughters were studied. For research, PCR diagnostics of daughters in the herds of black-and-white cattle at the farms "Azeleevo" and "Vakhitovo" (OJSC "Red East Agro") was carried out, the fathers were two bulls LADDIE 135797213 with a genotypes CSN3 AB and LOMAX 10785322 with a genotype CSN3 BB. Based on the results of genotyping, the frequency of occurrence of genotypes AA, AB, BB kappa-casein and allelic variants A and B in daughters was calculated. The bull with the CSN3 AB genotype produced the largest number of offspring with the CSN3 AA genotype - 50.0-51.8 %, and the bull with the homozygous BB genotype produced 24-25 % of daughters carrying the BB variant and 75-76 % of the AB genotype. The frequency of occurrence of the Kappa-casein allele in the daughters of bulls with the genotype CSN3 BB was 0.63, which is almost 2 times more than the allele A. When comparing heifers with the same genotype (CSN3 AB), it was found that at the Azeleevo farm, the daughters of the bulls having the genotype BB of kappa-casein are superior to cows born from bulls with the genotype AB by the milk yield (+36 kg), mass fraction of fat and protein (+0.01 %), the amount of milk fat (+2 kg) and protein (+2 kg). In the group of first-calf heifers with the BB genotype, daughters of the producer with the BB genotype are superior by the milk yield (+ 175 kg), the mass fraction of fat in milk (+0.1 %), the amount of milk fat (+12 kg), the mass fraction of protein in milk (+0.09 %), the amount of milk protein (+11 kg). At the Vakhitovo farm, similar results in the group of CSN3 AB heifers born from the bulls with the BB genotype was observed