Effects of Oxidative Stress and Antioxidant Activity in Plasma and Uterine Fluid During Early Postpartum on Subsequent Reproductive Performance of Japanese Black Cows

This study aimed to investigate the effects of oxidative stress and antioxidant activity in plasma and uterine fluid during early postpartum on the reproductive performance of Japanese Black cows. A total of 17 Japanese Black cows were included in this study. Plasma and uterine fluid samples were collected at days 7 and 14 of the estrus cycle (n = 17), between 47-67 days postpartum, and diacron-reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) were measured. d-ROMs, BAP, and oxidation stress index (OSI: d-ROMs/BAP × 100) were compared between pregnant and nonpregnant cows at first postpartum artificial insemination (AI), cows pregnant less than 120 days postpartum (<120 days postpartum), and cows pregnant more than 120 days postpartum (≥120 days postpartum) regardless of AI number. The uterine fluid OSI on day 7 of the estrus cycle was significantly higher in cows pregnant ≥ 120 days postpartum (<i>p</i> < 0.05). d-ROMs, BAP, and OSI of uterine fluid during early postpartum were useful indicators for determining the subsequent reproductive performance of Japanese Black cows.