The intensity of herd reproduction has a direct impact on the efficiency of dairy cattle breeding. The purpose of the research is to study in a comparative aspect the reproductive characteristics of the daughters of domestic and foreign breeding bulls on the breeding stock of 9,980 cows of the first calving of the modern population of the black-and-white breed in the Vologda Oblast. We have carried out an individual evaluation of servicing bulls by the method of rating assessment on a set of characteristics. The research establishes the superiority of the offspring of foreign bulls in terms of the average indicators of the studied traits with confidence (P < 0.001). The daughters of foreign servicing bulls have a lower insemination index of 0.08, the service period is shorter by 15 days. These animals also have fruitful insemination and the first calving at an earlier date – the average age of fruitful insemination is 0.6 months less than that of the daughters of domestic bulls, and the first calving is 0.7 months (P < 0.001). Among foreign breeding bulls, in comparison with domestic producers, there are more percentage of those whose daughters’ indicators correspond to optimal values: according to the insemination index by 9.8%, the service period by 27.8%, the age of the first fruitful insemination by 36.0% and the first calving by 39.2%. When using the rating assessment method for a set of signs of daughters’ reproduction, we have revealed that 74% of servicing bulls with optimal values of all signs in their offspring are of foreign breeding. In order to increase the competitiveness of domestic servicing bulls when securing breeding stock, it is necessary to take into account the evaluation of the bull by the reproductive offspring characteristics. In the black-and-white breed, to improve reproduction indicators, we propose to use bulls with the best characteristics according to reproductive features, selected by the rating assessment method according to a set of signs
Keywords
rating, black-and-white breed, selection, Selection, reproductive, servicing bulls, cow of the first calving, set of signs