Features of selection of cows by the lactation consistency index

Practice has shown that during comparing sires with using different evaluation methods the most accessible, fast and, in part, visual is comparing the productivity of daughters with the productivity of dams. The purpose of the research was to study and evaluate the features of cow selection based on the lactation constancy index. The material on comparing the productivity of daughters of individual sires with the productivity of their dams and dams of their fathers has been presented in the article. On the materials base of breeding documents, the results of long-term studies on the study of milk productivity indicators in cows of different genotypes and with different lactation constancy index were summarized. All cows were divided into groups based on the lactation constancy index. Thus, the 1st group of cows had a lactation constancy index ≥100 %, the 2nd group <100 %. The dams of these daughters and the dams of the fathers were assigned to the same groups. Thus, one of the methods for evaluating cows by productivity was considered, which allowed us to draw a number of conclusions. It has been established that there are significant differences in milk productivity between animals of different origin and with different lactation constancy indices. In most cows with different lactation constancy indices, the productivity in the fi rst lactation was inferior to the productivity of their dams. These differences mainly depend on the quality of the sires and the degree of realization of the hereditary material. Therefore, when using stud bulls, it is necessary to take into account not only the productivity level of the dams of sires, but also the lactation constancy index of their daughters, as one of the simple and accessible methods for assessing milk productivity.