Organisation of dairy cattle herd reproduction

A fairly high hereditary potential of cows of modern Ukrainian breeds in terms of the main traits of milk production is discussed. It was found that higher milk yield, content and amount of fat in milk are inherent in cows of the Ukrainian Black Speckled Dairy breed, which in the context of the four evaluated lactations were better, except for the third (where no clear leader was found for the main traits). In modern high-yielding herds of Ukrainian cattle, the duration of lactation, regardless of the genotype with or without Holstein bloodlines, exceeds the optimal value (305 days), which is associated with later insemination of cows after calving and an extended service period. Therefore, when assessing the efficiency of dairy cows, it is advisable to take into account the number of milk days and adjust their milk production and reproductive capacity accordingly. And the effect of Holsteinisation on the lengthening of the lactation period occurs only in the herd of the Ukrainian Black Speckled Dairy breed. The milk yield reflex of the cows of the studied breeds is within the limits of the accepted optimal indicators, which indicates their good adaptability and adaptation to the technology of machine milking, and the live weight of animals of the three studied breeds at the end of the growing period is within the breed standards. However, it is higher in the Red and Black Speckled Dairy breeds, which indicates their better ability to high growth intensity under appropriate growing conditions and, as previous studies have shown, to better milk production. The degree of development of the main body structure measurements of cows is within the standards and corresponds to the norms of the dairy cow type, and no clear advantage in favour of a certain group of cows was found for the main measurements. The height at the withers, depth and width of the chest are better developed in Ukrainian Black Speckled Dairy cattle, and the oblique length of the body and the girth of the metacarpal — in the Ukrainian Red Dairy breed, with a larger girth of the chest in the Ukrainian Red Speckled Dairy breed. The analysis of the reproductive function of cows gives grounds to assert that among all the studied breeds there is a significant deterioration, which leads, regardless of breed affiliation, to an increase in the duration of service period (128–132 days) and the period between calvings (406–423 days), and this negatively affects the calf yield per year and, as a result, significantly increases the insemination index (6.40–6.59). The analysis of correlations between the main selection traits of mothers and their daughters established high predictions for their inheritance (0.48–1.06), which will significantly increase the efficiency of selection for milk yield and milk fat in these herds of modern breeds.