Effect of DL--Tocopherol Acetate on Calving Induced Oxidative Stress in Periparturient Crossbred Cows During Summer and Winter Seasons

Twelve crossbred cows of high body condition were selected from the Institute herd, each in summer and winter season. Six cows were kept as control and six were supplemented withαtocopherol acetate during dry period for two months, during both the seasons. The blood samples were collected at 20, 10 and 5 days before calving, on the day of calving and 5, 10 and 20 days after calving. The body condition score of all the experimental animals was recorded on the day of blood collection. The activity of SOD and catalase enzymes was estimated in blood lysate. In plasma samples vitamins (α-tocopherol and retinol) and minerals (Fe, Cu, Zn and Mn) were estimated. At parturition, BCS in control and treatment groups decreased by 20.17 and 12.5% during summer and 16.60 and 8.99% during winter from 20 days prepartum. The activity of SOD enzyme was significantly (P<0.01) lower in treatment group than in control group, in both seasons. SOD and catalase activity increased upto calving and then decreased. SOD and catalase activity were positively correlated (P<0.01) to each other. Overall average value of α-tocopherol and retinol in control group cows during summer was 2.11 ± 0.03 and 0.76 ± 0.01 and in treatment group the values were 2.67 ± 0.04 and 0.80 ± 0.01 μg/ml, respectively. During winter the respective values in control group were 2.24 ± 0.04 and 0.79 ± 0.01 and in treatment group the values were 2.85 ± 0.04 and 0.85 ± 0.01. Overall Average values ofα-tocopherol (P<0.01) and retinol (P<0.05) were significantly higher in treatment group as compared to control group during both the seasons. Cu was significantly higher in treatment groups during summer and winter, while Fe, Mn and Zn did differ significantly in both the seasons. It was evident from the cows experience oxidative stress during the periparturient period, α-tocopherol supplementation reduces it by improving antioxidant status of cows.