SEASONAL CHANGES IN THE PRODUCTIVITY OF FIRST CALVING COWS UNDER DIFFERENT HOUSING

Abstract

The influence of the calving season on milk production was determined to be 0.9% for 305 days of lactation on average across all farms. In loose-housing, the influence of the season was smaller (0.4%) compared to stall housing (1.6-5.5%). Seasonal differences in the milk output of first calving cows for stall housing was equal to 437-816 kg, and for loose-housing 192-283 kg (р<0.05). In some farms animals of autumn and winter calving were distinguished by the best milk output, while in other farms spring-winter calving cows were more productive. It indicates a significant influence on the production of first-borns by the conditions of housing. The analysis of the indices of lactation constancy according to I. Johansen and A. Hanson indicates that the smallest decrease in milk output in the period of the next 14 weeks of lactation compared to the first 14 weeks of lactation was characterized by the first-borns of the experimental farm "Kutuzivka", and the largest by the animals of the experimental farm "Gontarivka". According to H. Turner's index, the differences between the peak monthly milk output and the milk output per lactation were the smallest in the first calving cows of the experimental farm "Stepne". Lactation curves of the cows that calved in the autumn-winter period had a steady character, which gradually decreased at maximum productivity for 3-4 months of lactation. In the first 3 months of lactation their herdmates of spring-summer calving also had an increase in milk output which fell dramatically in the following months when the animals were conveyed to winter-stall housing and a decrease in the completeness of feeding cows during this period. According to variance analysis, differences in daily milk output for each of the ten months of lactation were possible (p<0.001). The highest peak of daily output in all farms was obtained from first calving cows of spring calving which explained by the best conditions of housing and feeding during the calving period. Seasonal differences in the peak daily milk output of first calving cows ranged from 2.0 to 2.5 kg for stall housing and from 1.2 to 1.4 kg for loose-housing (p<0.001).