OXIDATIVE STRESS BIOMARKERS IN TRANSITION PERIOD IN DAIRY COWS

The present study was conducted to evaluate the oxidative stress parameters during the transition period in dairy Holstein cows. A total of 20 Holstein dairy cows were recruited from a private farm in Sohag governorate for the study. The oxidative stress parameters were evaluated weekly during the transition period (21 days before and after calving), where successive blood samples were collected from each of the recruited cows on days 21, 14, and 7 before calving (prepartum period), on calving day, and on 7-, 14-, and 21-days post calving (postpartum period). The obtained result revealed that glutathione peroxidase significantly (P < 0.001) decreased in the post-partum period, compared to the prepartum period. Interestingly, SOD significantly (P < 0.001) increased on the day of calving when compared to their level at the pre-partum and post-partum periods. In addition, MDA showed a significant (P < 0.001) increase on the 7th day after parturition, compared to the pre and postpartum periods. A significant (P < 0.001) decrease in serum Triglycerides, VLDLs, HDL, LDL, and TC was evident starting 3 weeks before parturition till 7 days post calving, then started to increase. A significant (P < 0.001) increase of glucose level was also evident on the day of calving as compared to prepartum and postpartum. In conclusion, the transition period in cows can impose oxidative stress, as indicated by an increase in MDA accompanied by a marked depletion in the antioxidant. Stress due to calving has greater effect on this imbalance.