Reproductive and productive traits of cows of Holstein breed depending on the level of inbreeding

Inbreeding is one of the main criteria in programs for the conservation and use of genetic resources, and it can be used to control genetic processes in populations of farm animals. The use of inbreeding involves the production and consolidation of rare genotypes, which determine the outstanding quality of animals. The purpose of the work was to determine the reproductive and productive traits of cows of Holstein breed depending on the level of inbreeding. The research was carried out in the pedigree farm in the Kaluga region. The research of the reproductive ability of first-calf heifers obtained through inbreeding and outbreeding were shown significant differences in the duration of the calving interval. So, cows obtained through the remote inbreeding had the lowest duration calving interval (385.4 days) and their herdmates from outbreding had the longest calving interval (404,5 days), the difference was 19.1 days (p<0.05) or 5.0%. Cows from remote inbreeding had the shorter calving interval than their herdmates from moderate inbreeding by 15.9 days (p<0.05) or 4.1%. It was found that higher milk yields for 305 days of the first lactation had cows obtained through remote inbreeding (6413.1 kg), and low milk yields of milk were obtained from first-calf heifers from moderate inbreeding (5634.8 kg), the difference was 778.3 kg (p<0.05) or 9.0%. They also surpassed the milk yield of their herdmates obtained from outbreeding by 266.6 kg (p<0.05) or 4.3%. First-calf heifers obtained through moderate inbreeding were inferior in milk yield to herdmates from outbreeding by 511.7 kg or 9.1% (p<0.05).