The conjugation of productive features of dairy cattle of the Holstein breed

Relevance. Currently, in the Sverdlovsk region, more than 75% of the total number of cattle belongs to the Holstein breed, created by absorbing domestic black-and-white cattle into Holsteins. The study of the variability of the productive qualities of cows during lactation is important for identifying the possibility of increasing productive longevity and the efficiency of breeding and using Holstein cattle of the Ural selection in the conditions of the Middle Urals.Methods. The study was conducted in one of the typical livestock complexes of the Holstein black-and white cattle breed in the Sverdlovsk region. All cows that completed four lactation periods were included in the assessment. Milk productivity was assessed by control milks, milk quality indicators: MJ and MDB in milk in an average milk sample from each cow, once a month correlation coefficients between productive characteristics were calculated in the Uralplemcenter dairy laboratory. The automated program “SELEX. Dairy cattle.”Results. As a result of the conducted studies, it was found that significantly more milk was produced from age-and-sex cows during the third lactation than during the first and second, as well as the fourth lactation (p ≤ 0.01 — for the first, p ≤ 0.05 — for the second and fourth). The live weight significantly increased with age in the second lactation at p ≤ 0.01 relative to the first, and from the third onwards — at p ≤ 0.001 relative to the first lactation. There is a tendency to decrease the mass fraction of fat (MJ) in milk and a simultaneous increase in MDB with age from the first to the fourth lactation. When carrying out breeding work, it is possible to take into account the positive correlation coefficients for predicting the further milk productivity of cows according to the milk yield of the first heifers, the invariance of milk quality indicators with changes in milk yield and the positive effect of live weight of cows on their productivity. The research is exploratory and was carried out within the framework of scientific research of the Ural State Agrarian University (state registration No. AAAA19-1191014000069).