EFFECT OF VITAMIN E AND ZINC ON CELLULAR ANTIOXIDANT ENZYMES IN KARAN FRIES COWS DURING TRANSITION PERIOD

The present study was conducted to explore the effect of vitamin E and zinc on oxidative stress and antioxidant enzymes during transition period in Karan Fries cows. Sixteen crossbred Karan Fries cows with confirmed pregnancy were selected two months before expected date of calving. The cross bred cows were randomly distributed in to two groups: eight cows were kept as control and eight cows were supplemented with vitamin E @ 1000 IU and zinc @ 60 ppm. Vitamin E and zinc supplementation was started from two months prepartum to two months postpartum. Blood samples were collected on the days -60, -45, -30, -15, -7, 0, + 7, + 15, + 30, + 45 and + 60 with respect to expected date of calving and plasma was separated. The plasma samples were analyzed for antioxidant enzymes (Superoxide dismutase, Catalase and Glutathione peroxidase), minerals (Zn, Cu, Fe and Mn) and vitamins (E & A). The activity of plasma superoxide dismutase, catalase and glutathione peroxidase were significantly lower (P< 0.001) in treatment as compared to control cows (139.16± 0.87 vs. 146.98± 1.87 units/L; 23.06± 1.89 vs. 25.14± 1.85 nmol/min/ml and 78.43± 6.35 vs. 79.01± 4.90 nmol/min/ml, respectively). Plasma vitamin E and A were significantly (P< 0.001) higher in treatment group than control group (2.60± 0.05 vs. 2.38± 0.06 and 0.83± 0.01 vs. 0.79± 0.01 μg/ml, respectively). Plasma vitamin E decreases towards calving and this decrease was more significant (P< 0.001) from 30 days before calving to the day of calving in control group than treatment group. Plasma Zn was significantly (P< 0.001) higher in treatment group than control group (1.68± 0.03 vs. 1.52± 0.03). Plasma Zn level decreased at the time of parturition, this decrease was more significant (P< 0.001) from 7 days before calving to the day of calving in control group as compared to treatment group. Plasma copper, iron and manganese did not vary significantly in control and treatment group. The results of this study indicated that supplementations of antioxidants like vitamin E and zinc have beneficial effects in improving the antioxidant activity and decrease oxidative stress to animals.