Reproductive qualities of cows with varying degrees of inbred

In dairy herds of Holstein cattle, there is an increase in the number of animals obtained as a result of closely related breeding and inbreeding, which is associated with the long-term use of Holstein breeding bulls, which are obtained using inbreeding to preserve and enhance beneficial traits. The aim of the work is to study the reproductive qualities of cows depending on the type of selection and the degree of inbreeding. It has been established that in almost all groups there is an excess of the optimal length of the technological period of 365 days. This difference ranges from 16 days (close inbreeding) to 33 days (close inbreeding). In the other groups, the difference is between these figures. Moreover, the difference between cows with close inbreeding and other groups of animals in terms of the length of the interbody period is significant at p< 0.05–0.01 in favor of the former. The CFS was in the range of 0.92–0.93 in all groups of cows, regardless of the degree of inbred. The exception was cows with close inbreeding, but their number was insignificant compared to other groups. There is no definite relationship between the duration of the service period and milk yield during lactation. An increase in the duration of the service period does not significantly affect the milk yield for lactation in cows of outbred origin, which, with sufficiently high rates of its continuation, are inferior in milk yield to cows of other groups, with the exception of cows obtained as a result of close inbreeding.