Correlations of reproduction and productive traits in Holstein cows during dynamics on lactations

Abstract

The task facing livestock breeders is to get a calf from each cow during the calendar year. Insemination of cows in the fi rst two months after calving is a necessary condition for increasing the rate of reproduction of livestock on the farm and increasing the economic effi ciency of the dairy industry. The purpose of the work was to evaluate the correlations between reproduction and productive traits in dairy cattle of Holstein breed, taking into account age in lactations. It was established as a result of the research that the herd has a large number of young cows in their fi rst and second lactations. The highest productivity indicators were found in cows in the third lactation, then there was a decrease in milk yield until the end of their use with slight fl uctuations in the direction of increase or decrease in milk yield, but in any case they turned out to be lower than in the third lactation. The mass fraction of fat in milk is a fairly stable indicator, as is the mass fraction of protein. The duration of the period of open days generally exceeded the optimal norms by 13–24 days or 14,4–26,7 %. This leads to the increase in the duration of lactation and the calving interval. The reproductive effi ciency coeffi cient ranged from 0,97 (9 and 10 lactations) to 0,91 (1, 5 and 11 lactations) and was mostly below 0,95, but tended towards this indicator. It can be concluded that the breeding stock in the dairy cattle herd of the breeding farm has satisfactory reproductive traits and there are certain problems with reproduction. The reliable influence of the duration of the period of open days on the milk productivity of cows has not been determined. Based on milk yield during early lactation we can predict about the further productivity of cows.