About the relations of the reproductive ability of the cows and their milk yield

The Holstein hybrids of different phenotypic groups by reproductive ability were estimated in order to identify the valuable genotypes that have high milk production which would successfully combined with good reproductive performance. The researches have been conducted on thoroughbred and local cattle population Black-and-White breed (genotype 3/8HF, 1/2HF, 3/4HF). Studying the influence of genotypic factors we taking into account indicators of reproductive capacity, which characterized the level of reproductive health indicators and herds of dairy cows productivity. Based on the research results, it was found that the optimum reproductive abilities possessed hybrid animals with genotypes 3/8HF, 1/2HF. In particular, the average age at first calving have reached 30.6 months, which is 1.2% less than the control. Service-period was 11 days longer in comparison with the control and amounted to - 100,1 days (P