STRESSFUL SEASONAL FACTORS OF INFLUENCE ON MILK PRODUCTIVITY AND QUALITY OF COW’S MILK

The research is devoted to a topical issue – establishing the influence of seasonal changes on the quality indicators of cow milk in the forest-steppe of Ukraine. Researchers from different countries and climatic regions have proven the impact of seasonal changes on the milk productivity of cows. Studies were conducted on cows of the Ukrainian red-pock dairy breed, in which milk productivity was taken into account by the method of control milking during January-August and the fat and protein content in milk was determined. The experiment was divided into three stages according to the actual ambient temperature: I – from -3 °C to +9 °C, II – from +10 °C to +24 °C, III – from +24.5 °C to +36.4 °C. the actual average air temperature was – +7 °C, +21 °C and 28 °C, respectively. At the first stage of the experiment, the average daily milk yield of experimental cows was 19.6 kg, during the first – the coldest period of research (from January 2 to March 25) – their productivity increased by 0.2 kg. At the second stage of research, during the spring warming (from March 26 to May 26), the average daily milk yield increased by 0.7 kg. At the end of the hottest third period of the study (from May 27 to August 31), the daily milk yield decreased by 1.1 kg compared to the first period and by 1.8 kg compared to the second period. Differences between the indicators of fat and protein content in the milk of experimental cows were established. At the first stage of the experiment, the average fat content in the milk of experimental cows was 3.93%, protein ‒ 2.98 %. During the coldest period of the year studied, the fat content in milk increased by 0.14 % (p<0.01), protein – by 0.24 % (p<0.01). At the end of the second stage of the study, the fat and protein content in milk increased slightly, by 0.05% and 0.02%, respectively. During the hottest period of research, the fat content in the milk of experimental cows increased by 0.14 %. The protein content in milk decreased slightly (by 0.06%) at the end of the third study period. Thus, it is proved that seasonal changes affect the milk productivity of cows, in particular, the daily milk yield, fat and protein content in milk, which is consistent with studies by other scientists conducted in different countries. Further research should be aimed at finding innovative ways to offset the negative factors of seasonal changes on the productivity of dairy cattle.