This study was carried out to investigate the changes in oxidative stress and some biochemical parameters in cows that were repeat breeder. A total of 40 Holstein cows were used in the study, 20 of which were repeat breeders between the ages of 3 and 8 and 20 of which were not fertilized. In all animals plasma malonaldehyde (MDA), catalase (CAT), glutathione (GSH), glutathione peroxidase (GSH-Px), serum triglyceride, cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), alkaline phosphatase aspartate aminotransferase (AST) levels were determined. As a result, MDA levels were found to be statistically higher (P<0.001), GSH (P<0.01), GSH-Px (P<0.001) and CAT (P<0.001) levels were lower in the control group than in the control group. In addition, triglyceride (P<0.05) and LDL (P<0.01) levels were higher in the control group than in the control group and HDL level was higher in the control group than in the control group (P<0.001). AST, ALT and cholesterol levels were not different between the groups.

As a result, it was determined that oxidative stress and antioxidant enzyme levels were decreased in cows repeat breeder, and lipid profile was also different between groups.