Abstract
The article presents the results of milk productivity of purebred heifers of the black-and-white breed and its crossbreeds with holsteins. It was found that for 305 days of lactation, black-and-white cows produce an average of 7910 kg in the herd with a mass fraction of fat in milk of 3.76%. From the first heifers in the first lactation, 7003 ± 158.1 kg are milked with a live weight of 638 ± 18.2 kg. From fullaged cows of the 3rd and subsequent lactation, 8178 ± 125.9 kg are milked with a live weight of 697 ± 18.4 kg. The fat content in milk varies from 3.80% to 3.82%. Cows of the breeding core produce 9341 ± 184.2 kg of milk, of the breeding group 8921±97.7. It has been established that the Holstein breed of black–and–white color has a positive effect on increasing milk yields, milk fat and protein yield during lactation, improving the technological and morpho functional properties of the udder, as well as on the lactation curve, which is more balanced and smooth than that of domestic dairy cows. The results of the research showed that in the herds of JSC APK "Adal" in black-and white and Holstein cows, the duration of the service period varied from 149 to 158 days. The intercalving period ranged from 432.6 to 439.4 days, the age of the first calving in black-and-white was 843 days and holsteins were 794 days, the coefficient of reproductive ability was 0.84 and 0.83 units, which meets the requirements of highly productive dairy cattle breeding.