DAIRY PRODUCTIVITY OF COWS OF DAUGHTERS OF BULLS OF DIFFERENT LINES AND GENOTYPE OF KAPPA-CASEIN
The aim of the study was to study the milk productivity of cows of daughters of sires with different linear affiliation and kappa-casein genotype. An analysis was made of the productivity of Black-and-White cows, originating from 60 sires of different lines, as well as those evaluated by the kappa-casein gene, which were used in Krasny Vostok Agro JSC. It has been established that cows of the R. Sovering line are characterized by the highest rates of economically useful traits, with an advantage in milk yield by 65-281 kg, in live weight by 6-24 kg, in terms of milk production index by 1-8 kg, in terms of milk yield by 0.01-0.12 kg/min. The worst indicators of productivity were found in animals of the Governer line. In general, interstrain differences are not high and productive indicators are within the normal range. When analyzing the milk productivity of the daughters of sires, carriers of various kappa-casein genotypes, it was revealed that cows of fathers with the AA genotype for kappa-casein have higher quantitative indicators of milk productivity and significantly (P<0.05-0.001) exceed the CSN3 AB and CSN3 EE by milk yield per 254-715 kg, by the amount of milk fat by 8.5-23.9 kg, by the amount of milk protein by 9.2-27.2 kg. At the same time, daughters of bulls with the CSN3 AA genotype are characterized by the maximum proportion of milk protein in milk, with an advantage over other groups by 0.03-0.12% (P<0.05-0.001). The CSN3 EE group is characterized by a high fat content in milk (4.11%) and exceeds other groups by 0.07-0.10% (P<0.01-0.001). Thus, the daughters of bulls with the AA CSN3 genotype had a higher milk production.