Oxidative stress and antioxidant status in dairy cows during prepartal and postpartal periods

The aim of the present study was to evaluate the indicators of oxidative stress (malondialdehyde [MDA]) and antioxidant status (ferric reducing ability of plasma [FRAP]; superoxide dismutase [SOD]; glutathione peroxidase [GSH-Px]; selenium [Se]; vitamin E) in dairy cows of the Slovak Pied cattle from 3 weeks before parturition to 9 weeks after parturition. The mean MDA concentration was significantly (P < 0.001) higher in the cows 1 week after calving compared to the cows 3, 6, and 9 weeks after calving. The lowest mean FRAP value was found in the cows 3 weeks after parturition. The SOD activities were increased during the whole monitored time (ANOVA, P < 0.001). A significant (P < 0.05) decrease of GSH-Px activities was recorded in the cows 1 week after calving compared to the weeks 6 and 9 after calving. Statistical multiple comparison test showed no significant changes in Se between the examined groups. The lowest mean vitamin E concentration was found in the first week after parturition. Significantly positive correlations (P < 0.05) were recorded between Se and vitamin E (r = 0.897), SOD and GSH-Px (r = 0.903), while Se and GSH-Px had no significantly positive correlation (r = 0.520). Significant changes between MDA and indicators of oxidative stress (SOD, GSH-Px, vitamin E) confirm that during parturition and onset of lactation, oxidative stress occurs in dairy cows. Exposure of peripartal cows to oxidative stress may cause an increased incidence of metabolic diseases. Peripartal period, lactation, malondialdehyde, antioxidants, diseases Oxidative stress plays a key role in the onset or progression of numerous human and animal diseases. Dairy cows undergo this deleterious process mainly during the peripartal period. The period of transition between late pregnancy and early lactation is associated with lipid and protein metabolic changes (Cast i l lo et al. 2006). The energy reduction in the first weeks after parturition results in increased fat mobilization, which is related to the generation of lipid peroxides and reactive oxygen species (ROS). These ROS are normally neutralized by sufficient antioxidant levels of living organisms. Imbalance between the production of ROS and the defence ability of biological systems to scavenge these reactive intermediates causes oxidative stress (Trevisan et al. 2001). This important mediator of cellular macromolecule damage must be continuously eliminated and controlled by antioxidant mechanisms to prevent various diseases occurring shortly after calving. Mastitis, metritis, and incidence of retained placenta are three common diseases linked to a compromised immune system. Many health problems also occur in young animals, such as increased neonatal mortality, decreased sucking reflex, weakness, white muscle disease and higher occurrence of infectious diseases (Sordi l lo et al. 2007). Adequate trace mineral and vitamin nutrition during the peripartal period is essential for an effective antioxidant defence system. It plays an important role in optimizing the immune responses and in helping the dairy cows to cope with the stress of early lactation (Spears and Weiss ACTA VET. BRNO 2015, 84: 133–140; doi:10.2754/avb201584020133 Address for correspondence: RNDr. Jana Konvičná Clinic of Ruminants University of Veterinary Medicine and Pharmacy Komenského 73 041 81 Košice, Slovak Republic E-mail: [email protected] Phone: +421 905 149 177 http://actavet.vfu.cz/ 2008). Direct protection of membrane lipids is provided by vitamin E which breaks the self-propagating chain of oxidative damage to the cell membrane. Deficiency of this antioxidant can cause increasing damage to the structure and function of cells (Sies et al. 1992) and therefore, antioxidant concentrations in animals need to be monitored. The objective of the present experiment was to study the degree of oxidative stress by evaluating the lipid peroxidation levels (malondialdehyde) and antioxidant status in dairy cows during prepartal and postpartal periods. The activities of main antioxidant enzymes (superoxide dismutase, glutathione peroxidase) and the ferric reducing ability of plasma concentration were determined, together with the concentrations of selenium and vitamin E. Materials and Methods