ASSESSMENT OF THE VARIABILITY OF REPRODUCTIVE ABILITIES OF A BLACK-AND-WHITE CATTLE USING GENEALOGICAL DATA AND PARATYPICAL FACTORS

The purpose of this study was to assess the role of paratypical and genetic factors in the variation of the complex of traits associated with the reproductive quality of livestock in the conditions of the CJSC breed livestock factory farm "Irmen" in a retrospective aspect. Black-and-White Irmenskiy interbreeds type breed was officially registered in 2000 by the Ministry of Agriculture of the Russian Federation as a breeding achievement and is a unique cattle subpopulation, bred only at the Irmen breed livestock factory farm, in Western Siberia, (Russia). This type is the best in all of Western Siberia in terms of milk yield and appearance among annual competitions and official state assessments. Therefore, the authors chose this breed as a material of research. Over 19 years, the authors studied the variability of traits such as milk yield, fat, protein content for 305 days of lactation, productive life, insemination rate, calving interval, open days, dry period, calving ease, and body weight. These traits are closely associated with the reproductive characteristics of the Black-and-White breed of the Irmensky subpopulation. The authors assessed the variability of these traits, which is influenced by the factors by "Year", "Lactation number" and "Sire's genotype". The data obtained showed a close genotype-environment interaction. Also, the conditions of feeding and keeping at the breed livestock factory farm have a significant impact on these traits.