The effect of holstein on the productive longevity of cows’ black-and- white breed in the conditions of the Smolensk region

The aspects of productive longevity of crossbreeds of Black-and- White cows with Holstein were study in the amount of 9270 heads that completed the cycle of production use, and for various reasons culling of the herds in the period 1990-2020. The research was carried out using the method of groupings based on pedigree farms of the Smolensk region. Phenotypic correlations between the studied economic traits are calculated. As a result of crossing with the Holstein breed, there was an active taking of the Black-and- White breed by it through breeding bulls to 90,0 % and higher a blood relationship in the conditions of the Smolensk region. A regularity has been revealed - the higher the blood relationship to the Holstein breed, the lower the lifetime of cows. The difference in lifetime of cows with blood relationship by the Holstein breed from 17,6 % to 87,1 % was 4,36 lactation. The duration of productive life of cows come to 12-13 lactation, 50,9 % of animals culling between 2 and 4 lactations. With age, the ratio of milk and dry days changes in animals, and the longer the period of use, the greater the number of milk days on average for each year of a cow’s life. The main part of the animals’ lactates within the ratio of milking days to days of life from 50,1 to 75,0 %. The level of lifetime milk yield in cows is mainly presented in gradations from 10 thousand kg to 30 thousand. kg (56,7 % of the studied cattle number). As an detector of productive longevity of cows, it is important to use the milk yield indicator for one day of life, due to the high positive relationships (r=0,44-0,90) with age and economic traits. The inventory of the Black-and- White breed in the conditions of the Smolensk region showed the indicate of its replacement with the Holstein, and further breeding of these animals will be purebred with the participation of only the Holstein breed.

black-and-white breed, crossing with the Holstein breed, lifetime milk yield, milk yield for one day of life