CHARACTERISTICS OF LACTATION ACTIVITY OF RED-STEPPE COWS DEPENDING ON THE CALVING SEASON IN THE KULUNDINSKAYA STEPPE OF THE ALTAI REGION
The productive qualities of cows and the hormonal status of the body are influenced by the factors of nutrition and housing environment. Under the conditions of the Altai Region, these factors undergo very significant changes during the year. The experimental part of the research on the influence of the season on the milk production of Red-Steppe cows was carried out on the farm of the SPK “Serebropol” of the Tabunskiy District of the Altai Region. Some groups of cows were formed; the cows calved in different seasons of the year. Altogether, 128 calvings were analyzed: winter - 13 heads, or 10.2%; spring - 20 heads, or 15.6%; summer - 41 heads, or 32.0%; and autumn - 54 heads, or 42.2%. When first-calf heifers calved in autumn and winter, their lactation curves were smoother and more levelled. When first-calf heifers calved in January and February, their lactation curves were more distorted. Rather steep rises alternated with deeper recessions. The most levelled lactation curve was observed in the animals that calved in August, but it had a very significant drawback - the maximum production was achieved on the first month. When the cows calved in March, May, June and July, their lactation curves had only one peak of milk production - on the 2nd and 3rd months of lactation. The highest milk production for lactation was obtained from the first-calf heifers that calved in October, November and December; their milk production ranged from 4466 to 4641 kg. The lowest milk amount was obtained from the first-calf heifers that calved in April, May and July. Their milk yield for 305 days of lactation ranged from 3434 to 3824 kg. The highest profit from the sale of milk was obtained from the first-calf heifers that calved in autumn and winter; the difference with the least productive cows amounted to 6032.3-7055.9 rubles. Under the conditions of the Kulundinskaya zone of the Altai Region, the calving dates of Red-Steppe first-calf heifers throughout autumn and winter period should be considered the most optimal.