The effectiveness of selection taking into account the linearity coefficient in the black-motley breed population

In modern dairy cattle breeding, genealogical lines are mainly used to systematize breeding material, much attention is paid to the use of leading bulls, which results in cross-breeding of offspring. In this regard, it is relevant to study the effectiveness of breeding selection, taking into account the genealogical affiliation of parents in the black- motley breed population. The study was carried out using the linearity coefficient as a tool for assessing the level of crossing in genealogical lines. The research base was formed using “Selex - Dairy Cattle” information and analytical system for 6,010 black-motley breed cows of the first calving from the breeding farms in the Vologda region, in which the data on pedigrees were verified according to the linear affiliation of ancestors up to the third generation, inclusive. As a result of the study, it was found that 81.6% of the controlled number of cows belong to the three lines of the Holstein selection: Vis Back Ideal 1013415, Reflection Sovereign 198998 and Montvik Chieftain 95679. The calculation and analysis of the linearity coefficient revealed the predominance of the black-motley breed of animals obtained by the method of crossing in the population lines - 90.4% of cows of the first calving have a linearity coefficient from 12.5% to 50%. A clear trend of growth in the genetic potential for the milk yield of cows of the first calving with an increase in the value of the linearity coefficient has been established. In the lines of Holstein selection, a direct positive relationship was found between the linearity coefficient and the milk productivity of cows. Therefore, for further growth in the productivity in black-motley cattle of Holstein breeding lines, it is advisable to adhere to the method of linear breeding. For cows of black-motley breed lines, it will be effective to cross-breed with bulls of Holstein breeding lines to obtain offspring with a linearity coefficient level of 12.5-37.5%. The study showed the feasibility of using the linearity coefficient method to determine the selection efficiency in dairy breeds populations.