Biochemical changes during heat stress in productive animals with an emphasis on the antioxidant defense system

The problem of free radical pathologies in high temperatures in animal husbandry and veterinary medicine is extremely important scientific and practical. In the process of hyperthermia, the structure of cell membranes, the permeability of membranes, and membrane transport systems change, which cause the oxidation of unsaturated fatty acids and the accumulation of toxic products of a radical nature. This plays an important role in the development of many pathological conditions. The review article describes the problem of the influence of heat stress (HS) on a living organism and the problem of hyperthermia in animal husbandry. Emphasis is placed on the role of the body's antioxidant system in a state of HS and the use of antioxidant drugs as additives into feed for farm animals, aimed at mitigating the course and harmful effects in HS. On the one hand, our goal was to describe in an accessible form the main complex biochemical disorders in the body under HS conditions, which lead to a deterioration in the welfare and loss of productivity of animals. On the other hand, we tried to show the special role of the antioxidant defense system in preventing the development of oxidative stress in its classical representation. Also, we substantiated the choice in favor of using natural and synthetic antioxidants as one of the strategies for the prevention of HS in modern animal husbandry.(AU)

Brown Swiss cows are more heat resistant than Holstein cows under hot summer conditions of the continental climate of Ukraine

Finding livestock breeds that are resistant to high temperatures may be one of the strategies for mitigating the impact of global climate change on dairy farming. In this investigation, we studied the heat resistance of Holstein (HB) and Brown Swiss (BS) cows on two commercial dairy farms under the hot summer conditions of Ukraine. The physiological response of animals determined heat resistance by measuring rectal temperature (RT) and respiratory rate (RR) in the morning (from 4:00 to 6:00) in comfortable conditions and the afternoon (from 14:00 to 16:00), during heat load. The temperature-humidity index (THI) was used to characterize weather conditions and microclimate in naturally ventilated rooms (NVBs). BS cows were found to be heat resistant. The reaction of HB cows to the heat was manifested by higher growth of RT and RR, and they suffered significant losses in the daily milk yield per cow in the summer. Further research will need to elucidate the biological and genetic mechanisms of the identified breed differences in heat tolerance of dairy cows.(AU)