Seasonal variability of cows reproductive capacity

For the last six decades the serious changes in dairy cattle breeding in the Far-Eastern region took place. These changes have occured in the technology of this branch management – from manual labour to the completely mechanized and even computerized farms. The breed composition was updated significantly, the Kholmogor and Sychiov breeds disappeared, Simmental livestock decreased Instead the animals of Holstein breed were imported. The dairy productivity increased from 1600 kg to 5000 kg of milk for lactation. However, the uneven distribution of calvings by year seasons remains unchanged. More than 60% of calvings take place during a winter-spring period, and it is unjustifiably from the point of view of economy and technology. The results of analysis of the primary zootechnical accounting for a number of years in the farms of the Middle Priamuryeshowed the dependence of artificial insemination of cows on the time of onset of oestrus after calving, and the longer this period is, the higher fertilization is. It was revealed the difference of the insemination results from number of cows in oestrus during the 24 hours. This dependence strengthens during the summer cattle maintenance on the pasture. It turned out that the temperature and the air humidity, quantity and duration of precipitation influence on the sexual behaviour of animals.