EXTERIOR AND CONSTITUTIONAL FEATURES OF FIRST-CALF HEIFERS OF BLACK-AND-WHITE CATTLE WITH DIFFERENT COMBINATIONS OF SELECTION

The development of dairy cattle breeding largely depends on the culture of young cattle breeding. It is very difficult to obtain and preserve young animals. Correct rearing of young cattle of dairy breeds contributes to the appropriate exhibition of genetically inherent productive abilities of animals during the first stage of their growth and development. When organizing breeding and feeding, animal growth and development characteristics are taken into account, which are determined by heredity and environmental conditions, especially feeding. The article provides a comparative analysis of the dynamics of live weight, measurements and body indexes of first-calf heifers of various selection combinations. First-calf heifers of the fifth experimental group, obtained from fathers and mothers belonging to the cross lines, exceeded animals in the control group, whose parents belonged to pure lines, in live weight and gains. Under the same housing and feeding conditions, the heifers of the studied groups did not grow in the same way, and certain differences were revealed in the process of ontogenesis. The first-calf heifers of the 5th group had the greatest live weight in different age periods and exceeded the peers of the 1st, 3rd and 4th groups from 10 to 23 kg with relevant difference. The animals of the 5th experimental group had the highest average daily gains till 6 months old. For the entire growing period (18 months), the animals in the control group had the highest relative gain, which was significantly higher than the gain in the experimental groups. The following body indexes were calculated: long-legged, elongation, pelvic-thoracic, thoracic; blockiness and bone index, as well as milk production coefficient which determined the direction of productivity of animals. First-calf cows were included into dairy-meat productivity direction according to the long-legged and elongated index. According to blockiness and thoracic index, animals of all groups belong to dairy direction of productivity, and according to bone index, to meat direction.