PRODUCTION RATES OF COWS OF DIFFERENT GENOTYPES
The article presents the impact of the degree of holsteinization of cows on the terms of use, the level of dairy products during the period of economic use, and reproducing qualities. The research was carried out in the conditions of the Vologda district. The sample included 592 black and mottled cows that dropped out of the herd in 2008-2017, with the first finished lactation. The analysis of longevity and reproducing qualities was carried out over seven years from the date of the first calving. Studies to analyze the effect of the Holstein genotype on productive longevity found that animals with a 26 to 49 % roofing differed in the duration of economic use (3,4 lactation and 1 569 days) and the lifelong productivity of base fat (27 104 kg). The animals with this geno type received the largest number of calves (4,1 heads) during the period of economic use. There was an increase in the multiple of insemination, reduction of the reproduction rate on reproducible qualities with an increase in blood 50 % or more. It characterizes the intensity of the process of substitution of endangered animals with non-animals, and as a result, lengthening of service and inter-period periods. The findings suggest that crossing black and mottled cows with holsteins and getting blood mixes from 26 to 49 % contributes to increasing the productive life expectancy of cows while increasing lifelong productivity while maintaining reproducing qualities at a reasonably good level.