Implementation of the genetic potential of foreign-bred bulls in breeding farms of Western Siberia

The large-scale use of breeding material from foreign selection in Russian dairy farming creates biological uncertainty due to the pronounced “genotype-environment” interaction effect. The study aimed to assess the realization of the genetic potential of foreign-bred sires under the conditions of breeding farms in Western Siberia. Based on productivity data from 28,065 first-calf heifers, 21 Holstein bulls were evaluated. The initial data were adjusted for the influence of year and season factors, and the farms were stratified into two categories based on productivity levels. The local breeding value was calculated as the mean of paired differences between the milk yield of daughters and the weighted average milk yield of their herdmates, with outliers iteratively removed. To assess the comparability with the foreign breeding value index, a categorical classification method by sign and a correlation analysis were applied. A strong “genotype-environment” interaction was established, manifesting in the re-ranking of sires across different farm categories. The analysis of sign concordance showed that the agreement between the local estimate and the foreign catalog’s forecast was no more than 50 %, which is equivalent to a random event. A complete sign match across all three estimates, including both local categories and the foreign index, was recorded for only 25 % of the sires. These findings were confirmed by a correlation analysis, which revealed a statistically insignificant relationship between the local breeding value estimate and data from the foreign catalog. The study concludes that the direct use of data from foreign catalogs for making selection decisions is unreliable. A local assessment of breeding value that considers specific production conditions is an indispensable tool for the objective selection of sires and for improving the efficiency of breeding programs.