Icariin improves pig sperm quality through antioxidant and antibacterial effects during liquid storage at 17 °C

Oxidative stress and bacterial contamination are two main factors affecting pig sperm quality. The objective of this study was to evaluate the effects of Icariin (ICA) on sperm quality, antioxidative and antibacterial activity during liquid storage at 17 °C. Boar semen was diluted into Beltsville thawing solution (BTS) containing different concentrations of ICA (0, 5, 10, 15, 20 and 25 mg/L). During storage, total sperm motility, progressive motility, kinematic parameters, acrosome and plasma membrane integrity, total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and reactive oxygen species (ROS) levels, bacterial content and the substitution effect of ICA for gentamicin (GEN) were assessed on days 1, 3 and 5, respectively. The results showed that supplementation of ICA in the extender not only significantly improved the antioxidant properties of sperm but also inhibited the growth of bacteria in semen, with 15 mg/L ICA showing the best performance on sperm quality. Furthermore, co-treatment of 15 mg/L ICA with 62.5 mg/L GEN showed similar effects on sperm quality and bacterial inhibition as 250 mg/L GEN, indicating that 15 mg/L ICA can replace 75% of the 250 mg/L GEN dose in semen extenders. Overall, we found that ICA can exert both antioxidant and antimicrobial effects to improve sperm quality and can also be served as an antibiotic substitute.