DYNAMICS OF MILK PRODUCTIVITY OF HOLSTEIN COWS DEPENDING ON AGE IN LACTATIONS

Abstract

Disadvantages and problems have been identified in the breeding of modern dairy cattle, among which a decrease in the productive longevity of the breeding stock is in the first place. The average duration of cow use in farms barely reaches 2.5 lactation. This reduces the efficiency of milk production. Research has shown that 82% of the total breeding stock consists of cows in the first and second lactation, and only 18% reach the age of physiological maturity. The highest productivity rates were found in cows in the third full-age lactation – 9780 ±144.09, which is more than in the first lactation by 711 kg and in the second by 618 kg, or by 7.3 and 6.3%. From the fourth lactation, there is a decrease in milk yield. Milk yield increases until the third lactation, and then begins to decrease, which corresponds to the physiology of lactation activity depending on age. The sharp decrease in milk yield after the fifth lactation is explained by the fact that in this group of cows there were animals with high milk quality indicators, but lower milk yields. In terms of milk yield, the quality of cow's milk, regardless of lactation, exceeded the minimum requirements for dairy productivity of Holstein cows. With an increase in milk yield from the first to the second lactation and from the first to the third, an increase in body weight is accompanied by a decrease in the coefficient of milk production while increasing body weight. An increase in live weight in a farm of more than 650-660 kg is not effective.