We investigated changes in oxidative stress markers during the transition period in healthy Holstein cows and those with postpartum diseases. Transition control (TC) Holstein cows
(n=9) were evaluated for longitudinal changes during the transition period and postpartum diseased (PD) cows with ketosis (n=10), abomasal displacement (n=9), and acute mastitis
(n=10) were evaluated in comparison to control cows (n=10). In the TC group, blood samples were collected at 2 weeks prepartum and at 1, 2, 4, 6, and 8 weeks postpartum. Milk yield
and composition were measured at 2 and 4 weeks postpartum. In the PD group, blood samples were collected at the first day of examination during the 60 days postpartum. Peripheral
oxidative stress parameters (malondialdehyde, MDA; potential antioxidant capacity, PAO; and glutathione peroxidase) were measured, and biochemical analyses were performed. In the
TC group, MDA increased significantly postpartum and was correlated with milk yield, blood glucose (Glu), free fatty acid (FFA), β-hydroxybutyric acid (BHB), and aspartate
aminotransferase. Compared to the control cows, PD cows with ketosis had significantly higher MDA and significantly lower PAO. Moreover, MDA was significantly correlated with Glu,
FFA, and BHB. Postpartum increase in MDA might interact with milk yield and Glu, FFA, and BHB in the TC cows, and postpartum diseases, especially ketosis, might signify its
increase and interaction with Glu, FFA, and BHB.