Effects of Oxidative Stress and Antioxidant Activity in Uterine Flush Fluid During Early Postpartum on Reproductive Performance of Lactating Holstein-Friesian Dairy Cows.

This study examined the impact of early postpartum uterine oxidative stress and antioxidant activity on subsequent reproductive performance in lactating Holstein-Friesian dairy cows. Uterine flush fluid samples were collected at 2-8 weeks postpartum (n = 77), and diacron reactive oxygen metabolites (d-ROMs), biological antioxidant capacity (BAP), and oxidation stress index (OSI: d-ROMs/BAP × 100) were calculated. Reproductive performance was classified into one of the following three patterns: Pattern 1, pregnant after first postpartum artificial insemination (AI) (n = 23) versus nonpregnant after first postpartum AI (n = 54); Pattern 2, pregnant < 120 days postpartum (n = 32) versus pregnant ≥ 120 days postpartum (n = 45); and Pattern 3, pregnant < 3 AIs (n = 45) versus pregnant or nonpregnant > 3 AIs (n = 32). There was a significant difference between the groups in d-ROMs at 5 weeks in Pattern 2 and 7 weeks in Patterns 1 and 3. There was no significant difference between the groups in BAP and OSI at any week. The results indicate that an increase in oxidative stress levels in the early postpartum period affects the reproductive performance of Holstein-Friesian dairy cows.