The use of resveratrol decreases liquid-extend boar semen fertility, even in concentrations that do not alter semen quality.

In vitro and in vivo assays were conducted to investigate the effects of trans-resveratrol (RVT) on liquid-extended boar semen during 72 h of storage at 17 °C. Thirty-six ejaculates were collected from six boars, evaluated, and extended. RVT was then added at the indicated treatment concentration (0, 0.01, 0.1 or 1 mM), and the ejaculates were cooled to 17 °C and evaluated at 0, 24, 48, and 72 h. Samples were evaluated for sperm motility, kinetics, plasma and acrosome integrity, mitochondrial membrane potential, anion superoxide levels, lipoperoxidation, and antioxidant enzyme activity. In the follow-up experiment, twenty-eight gilts were fixed-time inseminated with 0 or 0.01 mM RVT liquid-extended boar semen. After five days, they were slaughtered, and their reproductive tracts were recovered. The embryos were collected, and the pregnancy, fertility, and viable embryo rates were calculated. In the in vitro assays, total motility, plasma and acrosome membrane integrity, mitochondrial membrane potential, anion superoxide levels, and lipoperoxidation did not change at any of the evaluation times with the use of RVT up to 0.01 mM. RVT decreased SOD activity without changes in GPx. RVT used at 1 mM showed harmful effects for almost all evaluated parameters. For the in vivo assay, the same pregnancy and fertility rates were observed for both groups, while the viable embryo rate was three-fold lower in the 0.01 mM group than in the 0 mM group. The results showed a dichotomous effect of RVT; a low concentration was not harmful in vitro but was catastrophic for embryo viability.