THE INFLUENCE OF INTRAUTERINE HEIFER DEVELOPMENT CONDITIONS UPON THEIR FURTHER MILK PRODUCTIVITY

Abstract

Milk productivity in the daughters of Alatausky cows, whose milk yields are over 4200 kg, goes down if their intrauterine development runs in the years when the mothers lactate the most and the closest to them. This becomes particularly intensive in the cows yielding milk over 6.0 tsd. kg. It is established that the daughters being formed in their mother’s womb during the years of relatively small lactations have favorable conditions of intrauterine development. They are distinguished by higher milk productivity than the daughter-cows born in the years of the highest lactations. With the mothers’ growing milk yields, on average, some increase in their daughters’ milk productivity is observed, but within each group of mothers the produced daughters’ milk yields are different, the yields vary with the conditions of the daughters’ intrauterine development. Regarding productive traits, the daughters delivered by heifers do not yield to the daughter-cows that were born by older calving mothers, in some cases they even exceeding. Milk productivity of full sister-cows and half-sisters was different varying with their intrauterine development conditions, the animals of favorable embryo development period being distinguished by 512-535kg higher milk productivity for the first calving and the productivity was by 418-471 kg more for all the calvings as compared to group II cows, the degree of significance being reliable enough (P < 0.01).