Reproductive qualities of Holstein cows by lactation

Report. Reproduction is the second group of indicators that play an important role both in the organization of milk production and in improving the efficiency of the industry. The study and evaluation of the reproductive functions of Holstein cows, domestic breeding is relevant and has practical significance for dairy cattle workers. The purpose of the work is to evaluate the reproductive qualities of Holstein cows and their correlation with productivity. As a result of the research, it was found that cows in all lactation have an increase in the duration of the service period from 19 (1 lactation) to 29 days (4 lactation), or by 21.1% and 32.2%. This led to an extension of lactation by 32-52 days or by 10.5 - 17.0%. The coefficient of reproductive ability is 0.90-0.92, which indicates problems with reproduction. The duration of the service period has a direct impact on the level of reproduction of cows. With an increase in its duration, the coefficient of reproductive ability (CFS) decreases. With the age of cows, the reproduction rate decreases. The duration of animal use has a negative effect on the reproductive qualities of cows by reducing the ability to inseminate and increasing the duration of the service period and the frequency of insemination. It was revealed that the level of productivity of cows does not have a positive dependence on the level of reproduction. In this group of cows, there is a parallel decrease in milk yield and the coefficient of reproductive ability for lactation. An increase in milk yield has not been established with an increase in the level of reproduction. The highest yield was obtained with a decrease in reproductive qualities. The conclusion about the increase in productivity of cows with a decrease in reproductive functions is confirmed.