INFLUENCE OF THE EVALUATION INDEX VALUE OF SERVICING BULLS "PERIOD OF PRODUCTIVE LIFE / PRODUCTIVE LONGEVITY" ON THE REPRODUCTIVE ABILITY OF THEIR DAUGHTERS

Abstract

The genotype of the servicing bull has a great influence on the productive longevity
and reproductive capacity of dairy cows. Currently, in all countries with developed dairy cattle breeding, servicing bulls are evaluated not only for general indicators, but also for the
health of their daughters. One of such evaluation indices is the "period of productive life /
productive longevity". The use of servicing bulls with high value of this index in dairy herds
will improve the reproductive capacity and increase the period of productive use of animals.
The research was carried out in 2020 in the agricultural production cooperative collective
breeding farm "Kazminsky", Kochubeyevsky District, Stavropol Territory on holsteinized
first-calf heifers of Black Pied breed, which were the daughters of two servicing bulls with an
evaluation index of 117 and 105. It was found that in terms of reproductive capacity, the
daughters of a servicing bull with an evaluation index of 117 were superior to the daughters of
another servicing bull. So, the difference in the duration of the service period was 33.9 days,
and the insemination index was 0.77. In the group of daughters of the servicing bull with a
high evaluation index 50% of animals had a service period of less than 90 days, while among
the offspring of the servicing bull with a low evaluation index, only 29.5% of first-calf heifers
had such service period. Thus, it was found that the offspring of the servicing bull, whose
evaluation index value of "period of productive life / productive longevity" was 117, compared with the offspring of the servicing bull with an evaluation index of 105, according to
the results of the first lactation, differed in better indicators of reproductive capacity.