Ukrainian Journal of Veterinary Sciences

Thermal stress is a typical summer-time problem in high-yield dairy cows, regardless of the geographical location of milk production enterprises, and differs only in its degree of intensity. Increasing the incidence of thermal stress is likely to be a clear consequence of global climate change, which affects dairy cattle breeding and is due to an increase in the temperature of the environment. Thus, it is projected that Ukraine's dairy industry will operate in a warmer environment in the next decade, with increased demand for high-efficiency industries. Therefore, developing dairy farmers must be prepared for global climate change, and their veterinary support has to be adapted to these changes. It is necessary to evaluate the risks of thermal stress in dairy cows at the level of productivity and profitability of the dairy industry critically. In case of thermal overheating the behavior of cows, physiological processes, energy balance and the state of the antioxidant system in their organism change, what causes decrease of milk quality (decrease in the content of fat and protein), productivity (reduction of dietary intake), deterioration of the general condition, reproductive capacity, increased risk of occurrence scar acidosis, mastitis, endometritis and others. To prevent cow’s thermal stress the temperature and humidity index (THI) should be monitored within ˂ 72, with a temperature of not more than 24 ° C and a humidity of ≤ 70%. It is also necessary to change the conditions of retention and feeding timely and qualitatively to reduce the effect of thermal stress on highyielding cows.

highly productive dairy cows, heat stress, temperature-humidity index, body temperature, thermoregulation, cardiovascular insufficiency