The efficiency of the brown Swiss breed heifers in the selection process in the production agricultural cooperative "Novomikhaylovskiy"

Shortening the heifers breeding provides an opportunity to increase production, fertility and heifers output, to reduce the cost of feeds and increase the efficiency of their use. The efficiency of use of heifers’ reproductive abilities; milk productivity and change of indicators of reproductive ability for the first lactation taking into account the age of fertilization were studied. The studies were carried out in the breeding reproducer for the cattle of brown Schwyz breed production of the agricultural cooperative "Novomikhaylovskiy", Smolensk region. The object of the research is cows of the first calving with complete lactation (296 animals). The efficiency of heifers’ reproductive qualities with the application coefficient of their reproductive abilities was examined. At the age of fertilization up to 550 days, the utilization rate of reproductive abilities of heifers was 111.4%, which was an excellent indicator. From 551 up to 650 days the coefficient of the use of heifers’ reproductive abilities was 88.2%, and with the fertilization at the age of more than 901 days it was 47.1%. The maximum milk yield, fat and protein had heifers with the age of insemination 651-750 days. The genotypic variability of milk yield varies in the range of 21-27% of the heifers of group 1. With an increase in the age of first fertilization, the indicators of the reproductive ability of cows changed. In animals with the age of fertilization of 651-750 days a minimum period between calves and service-period, which are reliable in relation to the heifers VI on 61-60 days (p ≤ 0,001), also the reproductive capacity coefficient was the highest 98,5% (p ≤ 0,01; p ≤ 0,001). At cows for the first lactation in the conditions of economy, the best indicators of dairy productivity and reproductive abilities are recorded at the age of fertilization of 651-750 days.