Evaluation of Holstein sires by the quality of offspring
In the Sverdlovsk region in 2002, the Ural type of Holstein black-and-white cattle was officially registered. Its improvement continues through the use of the gene pool of the best breeding bulls of both domestic and foreign breeding. The evaluation of the breeding bulls used by the quality of offspring, namely daughters, in relation to the conditions of feeding and maintenance in each individual farm is relevant and has practical significance. It was found that the highest indicators for milk yield were the first heifers of the bull-producer Emer, who outperformed the daughters of other bulls by 329 - 716 kg or 3.6 - 7.7%. The greatest difference in milk yield between daughters and mothers in milk yield was noted in the group of daughters of the bull Emen. It was 4574 kg or 49.4% (P≤0.001). In the other groups, the superiority of daughters over mothers was 18.2; 24.5; 28.1% (P≤0.01). Based on this, we can say that all the bulls turned out to be improvers in milk yield. The daughters of the Knight-producing bull had lower milk yield indicators compared to their peers, that is, this bull turned out to be a degrader in this herd, despite the fact that the first-born heifers surpassed their mothers in milk yield. However, under these conditions of feeding and maintenance and the growth of the genetic potential of productivity, they turned out to be the worst. The daughters of bulls Malachite and Madboy had averaged indicators, compared with their peers, that is, they turned out to be neutral in milk yield, but had better indicators for MJ in milk. The bull Emer turned out to be an improved in milk yield and a degrader in fat content.