Oxidative indices as metabolic stress predictors in periparturient dairy cows

The aim of the study was to determine changes in reactive oxygen species (ROS), serum antioxidant capacity (SAC) and oxidative stress index (OSi; ROS/SAC) from dry off to 30 days postpartum in dairy cows. Furthermore, the relationship between indices of oxidative status (ROS, SAC, OSi) and indices related to metabolic disorders (blood free fatty acids, FFA and β-hydroxybutyrate, BHB) and α-tocopherol (α-Τ) was determined. Blood samples were collected from 131 dairy cows belonging to four commercial farms, located in Italy and Greece. Blood samples were collected at dry-off, calving and 30 days postpartum. Results indicated that ROS and OSi were low at dry-off and 30 days postpartum and high at calving. The serum antioxidant capacity followed exactly the opposite trend. There was a negative correlation of ROS (rho: −0.282; p ≤ .01) and OSi (rho: −0.267; p ≤ .05) with α-Τ at all three sampling points, whereas no correlation was found between SAC and α-Τ. Reactive oxygen species were positively correlated with BHB at all three sampling points and with FFA levels only at dry-off. A negative correlation of SAC with FFA was found at dry-off and 30 days postpartum. The oxidative stress index was positively correlated with FFA and BHB at dry-off, with FFA at calving and with BHB at 30 days postpartum. Thus, associations between parameters related to oxidative status and those related to energy balance were found, mainly at dry-off and postpartum. Oxidative stress markers determined at dry off could be useful in preventing metabolic disorders.