The influence of genetic and environmental factors on reproductive qualities of black-motley cows

One of the tasks of animal breeding - is improving the management of breeding and, especially, its biological factors (heritability, genetic correlations, the effect of heterosis, etc.). The situation is complicated by the fact that currently used in the selection of inbreeding. However it often conducts to display inbreeding depressions on intensity of growth, live weight, reproductive qualities and other selection signs. In scientific work the results of a comparative evaluation of productivity in the herd with inbreeding and conventional breeding. In the scientific is work studied the percentage of heifers and steers at calving, the number of calves-twins, stillborn calves and abortions in inbreeding and normal of animals groups. Inbreeding no had significant effect on stillbirths. The percentage of Holstein genes may influence of the sexes ratio in their offspring.