Influence of live weight on milk productivity and reproductive traits of cows

Abstract

Under conditions of intensive dairy cattle breeding, the effective realization of the genetic potential of cow productivity is largely determined by a complex of hereditary and paratypical factors, among which the most important place is occupied by the live weight of animals. Optimization of this indicator makes it possible to increase not only dairy productivity, but also the reproductive traits of animals in the herd. The purpose of the research was to evaluate the influence of live weight on dairy productivity and reproductive traits of cows. The research was carried out on the basis of the Ramzai Educational and Experimental Farm at Penza State Agrarian University. Two groups of first-calf heifers were formed. Cows in the group 1 (n=18) had a live weight of up to 550 kg, group 2 (n=42) were 551–600 kg. Indicators of milk productivity and reproductive traits were analyzed in experimental cows. It was found as a result of the carried out research that cows of the 2nd group significantly outperformed their herdmates of the 1st group in milk yield per 305 days of lactation (by 758.5 kg at p < 0.01), milk fat yield (by 29.7 kg at p < 0.05) and milk protein (by 24.2 kg at p < 0.01). There were no significant differences in the fat and protein content in milk. At the same time, the animals of the 1st group had an earlier age of the first fertile insemination (by 1.5 months at p < 0.05) and the fi rst calving (by 1.6 months at p < 0.01). Correlation analysis showed that in the 1st group of cows, an increase in live weight was moderately associated with an improvement in reproductive performance such as a shortening of the open days period (r = –0.47), an increase in calf yield (r = 0.47), and an increase in the reproductive coefficient (r = 0.41). At the same time, in the 2nd group of cows, these correlations were weak or absent. As a result, it was found that despite the higher milk yields of cows of the 2nd group, animals with a live weight of up to 550 kg are preferable for herd reproduction, since they provide better reproductive health and an earlier start of economic use. In order to increase the economic efficiency of milk production in conditions of farm, it was recommended to purposefully form a herd of cows weighing up to 550 kg.