The influence of ambient temperature on the productive traits and biological peculiarities of Black-and-White bulls in the early period of postnatal ontogenesis

The objective of this study was to identify the relationship between ambient temperature and the productivity, mineral, and antioxidant status of bull calves during the early period of postnatal ontogenesis. The research was conducted in the Orenburg region on Black-and-White bull calves which were divided into three groups according to the season of their birth: Group I – winter calving season (December calving), Group II – spring calving season (March calving), Group III – summer calving season (June calving). Feeding and keeping were similar for all animals in the studied groups throughout the experimental period. It was found that, starting from 3 months of age, the bull calves in Group II surpassed their peers from Groups I and III in terms of live weight and average daily gain. The intensive growth of the bull calves was accompanied by an increase in the blood concentrations of glucose, total protein, albumins, cholesterol, erythrocytes, and hemoglobin. The animals in Group II were characterized by increased activity of superoxide dismutase and catalase against a background of a relatively low concentration of malondialdehyde. High ambient temperature contributed to increased concentrations of Hg, V, Cr, Pb, and As and decreased concentrations of Mg, P, K, Ca, Sr, Na, B, Mn, and I in the hair of bull calves from the summer calving season compared to those from the spring calving season. Bull calves from the winter calving season had intermediate concentrations of chemical elements between the mentioned groups.