Интенсивность выращивания тёлок и их последующие воспроизводительные качества

The aim of the study was to identify the relations between heifer replacement live weight gain intensity along with subsequent calving and reproductive values. Items for 191 hei-fers from birth to 6 months of age, divided into 5 groups by average daily live weight gain values and stratified at the interval of 100g per day were surveyed. Most of the animals earlier affected by gastrointestinal and respiratory diseases appeared to be in the first group; average daily gain for them was 532 g in average. Calving Ease item was analyzed for 4 first-calf heifer groups, formed by average daily live weight gain from the birth to the fist fruitful insemination. The first group involved animals having gains of 700 g per day; and further, 3 first-calf heifer groups were identified using the same interval of 100 g per day as in the first case. It was ascertained that the easiest calving events were registered in the first-calf heifers with live weight gains from the birth to insemination within 700-900 g per day, and their age at first calving was 23 to 27 months of old. Among the cows of those groups, the service-period was running less. These parameters should be considered as optimal for the herd. Later, gynecological diseases were registered more often among the first-calf heifers with difficult calving; over 20% of heads from the first and fourth groups were culled out before the end of the first lactation. As reducing age at the first calving at less than 23 months as extending it beyond 27 months resulted in the frequency of a difficult calving that increased by 18-37% being the main reason to cull them out of the herd.