Relationship of Oxidative Stress and Some Blood Parameters with Quarters Affected by Mastitis in Dairy Cows

Background: This study was conducted to evaluate the relationship between oxidative stress and some blood parameters in different number of quarters affected with and without sub-clinical mastitis (SM). Methods: A total of 50 lactating Holstein dairy cows were used in the study. The study groups were as follows; Group 1 (negative test results and no SM), Group 2 (SM in one quarter), Group 3 (SM in two quarters), Group 4 (SM in three quarters) Group 5 (SM in four quarters). Milk samples were obtained from the infected quarters for both Somatic Cell Count (SCC) measurement and bacteriological growth/bacterial identification. Blood was collected for analysis of oxidative stress parameters (total oxidative capacity and total antioxidant capacity) and some blood parameters (glucose, total cholesterol, total bilirubin, aspartate aminotransferase [AST], alanine aminotransferase [ALT]). Result: Somatic Cell Count (SCC) was significantly lower in Group 1 than in Groups 2, 3, 4 and 5 (P less than 0.001). Glucose and total cholesterol levels were significantly higher in Group 5 than in Groups 1, 2, 3 and 4 (P less than 0.001). A significant difference was determined between all groups in respect of AST and ALT activities (P less than 0.001). The Total Oxidative Capacity (TOC) and oxidative stress index value (OSI) levels were significantly lower in Group 1 than in Groups 2, 3, 4 and 5 (P less than 0.001), while Total Antioxidant Capacity (TAC) levels were significantly higher (P less than 0.001). In conclusion, it was found that oxidative stress and blood-biochemistry values are significantly affected in dairy cows with sub-clinical mastitis.