Productivity of Holsteinized black-and-white cattle depending on age

Ural State Agrarian University, Karl Liebknecht 42, Yekaterinburg, 620075 Russian Federation

^* Corresponding author: olgao205en@yandex.ru

Abstract

The Ural type of the domestic black-and-white breed is characterized by high productivity and good suitability for use in the conditions of industrial milk technology. During its breeding, the use of purebred bulls-producers of the Holstein breed of both domestic and foreign breeding continues. As a result of the conducted research, it was found that the productivity of cows changes significantly with age. Milk yield for 305 days of lactation increases from 1 lactation to 3 lactation, and then decreases by 369 kg or 3.8% in the fourth, relative to the third, and by 2090 kg or 22.2% in the fifth, relative to the fourth. The productivity of full-aged cows is higher than that of young cows and can remain at a high level for a long period. The quality indicators of milk changed upward from the first to the fifth lactation. High correlation coefficients were established by the conjugation of milk quality indicators with each other, regardless of lactation. They ranged from 0.364 (2 lactation) to 0.533 (1 lactation). That is, a decrease or increase in MJ in milk will lead to the same change in MDB.