OXIDATIVE STRESS AND POSTNATAL ADAPTATION OF THE INTRAUTERINE GROWTH RETARDATED CALVES

During early postnatal adaptation, the equilibrium between pro-oxidant and antioxidant systems of the organism is unstable. The birth and switch to pulmonary respiration initiate a cascade a free radical reactions and leads to an excessive load on the antioxidant protection (AOP). Functional immaturity of AOP, caused by the intrauterine growth retardation of the embryo and fetus (IUGR), can lead to oxidative stress. In humans, these processes are well-known, but in animals, they are under-studied. Experiments on Simental calves ( Bos taurus taurus ) with IUGR (Group I, n = 30) and physiologically normal pregnancy in their mothers (Group II, n = 29) aimed to evaluate AOP (catalase activity, glutathione peroxidase (GPO) activity, superoxide dismutase (SOD) activity, concentrations of vitamin A, alpha-tocopherol, and L-ascorbic acid) and oxidative stress parameters (concentrations of malondialdehyde (MDA), diene conjugates (DC), and their ratio) in the blood 1, 7, 14, and 28 days after the birth. Laboratory tests were performed with spectrophotometer UV-1700 (“Shimadzu”, Japan). Statistical analysis was performed in IBM SPSS Statistics 20.0 software (“IBM Corp.”, USA). The authors used the MannWhitney U-test to reveal the differences between the samples of calves of the same age. Wilcoxon's test for paired data was used to evaluate the dynamics inside a group. The blood of neonate calves with IUGR showed increased activity of catalase (by 30.3%, p < 0.05), SOD (27.8%, p < 0.05), content of vitamin A (by 33.6%, p < 0.05), alpha-tocopherol (by 33.9%, p < 0.05), and L-ascorbic acid (by 47.4%, p < 0.05), elevated concentrations of MDA (by 29.9%, p < 0.05), DC (by 4.5%, p < 0.05), and the ratio of MDA/DC (by 26.6% (p < 0.05), respectively, in comparison with animals from Group II, which indicated functional insufficiency of their AOP. The dynamics of the content of MDA, DC, and the ratio of MDA/DC in the calves blood on days 1-28 of their life showed a decrease in the functional capacity of AOP and more intensive transformation of primary ROI into intermediate and final toxic products considering the age of animals.