An evaluation of the effects of alpha-tocopherol and ascorbic acid in bovine respiratory disease complex occurring in feedlot calves after transport

摘要

Taking into account the beneficial effects of antioxidants in reducing morbidity and mortality in calves, the aim of this study was to evaluate the effects of vitamins E and Con the development of the inflammation process and on selected defence mechanisms against infections induced by M. haemolytica.The study was carried out on 30 Simmentaler calves weighing about 100 kg, which received s.c. vitamin E (750 UI) or vitamin C (2.5 g/calf). In leukocytes obtained from the calves, sensitivity to the cytotoxic effect of M. haemolytica Lkt was evaluated using the MTT assay, expression of beta(2)-integrin receptors on leukocyte surfaces was assessed, and metabolic activity was measured by the nitrotetrazolium blue test (NBT). Concentration of haptoglobin (Hp) and serum amyloid A (SAA) was estimated in the sera obtained.Analysis of the intracellular metabolism of the leukocytes showed no statistically significant differences compared to the control. A difference (p <= 0.05) was observed in the sensitivity of the leukocytes to the cytotoxic effect of Lkt in comparison with the control group. No differences were found in the percentage of cells sensitive to Lkt between the group given vitamin E and the calves which received vitamin C. The percentage of expression of beta(2)-integrin receptors reached its lowest values on leukocytes isolated from the calves given vitamin E. The correlation between expression of beta(2)-integrins and sensitivity of leukocytes to Lkt showed the greatest correlation on day 14 in calves given vitamin E. and on day 21 in calves given vitamin C.Analysis of Hp concentration in the sera showed no differences between the two groups of calves tested, but revealed differences (p <= 0.05) in absorbance values compared to the control on particular days of experiment. SAA concentration in the sera of calves from the group that received vitamin E was similar to that of the control on days 14 and 21 of the experiment. On days 3 and 7 of the experiment a significant (p 0.05) decrease was observed in SAA in the sera obtained from calves from the group given vitamin E compared to the control and the group given vitamin C