Effect of different concentrations of resveratrol on the quality and in vitro fertilizing ability of ram semen stored at 5 °C for up to 168 h.

The aim of the study was to investigate the effects of different concentrations of resveratrol on head morphology, motility characteristics, oxidative state and in vitro fertility of cooled ram spermatozoa. Pooled semen from three Najdi rams was diluted with Triladyl® having different concentrations of resveratrol, zero (control), 200 µM (45.65 µg/mL) and 400 µM (91.30 µg/mL) resveratrol, then stored at 5 °C for 168 h. The head morphometric, sperm kinematic parameters, Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and in vitro fertilizing capability of ram spermatozoa were evaluated after 24, 72, 120 and 168 h of cooling storage. The total motility (TM) of the sperm with resveratrol at 200 µM and 400 µM was significantly (p ≤ 0.05) higher than that in the control group at 72 and 120 h of cooling storage. On the other hand, the progressive motility (PM) of the sperm with resveratrol at 200 µM and 400 µM was significantly (p ≤ 0.05) higher than that in the control group at 168 h of cooling storage period. After 168 h of cooling storage, significantly higher straightness (STR) was observed in 400 µM group than two other groups and in 200 µM group than the control group. Both resveratrol groups had higher linearity (LIN) than control one at 120 and 168 h of cooling storage. The length, width and area of sperm head were lower (P ≤ 0.05) in the control compared to the other treatment groups after 120 and 168 h of storage. There was a significant increase in superoxide dismutase (SOD) concentration in the two resveratrol groups compared with the control one over the seven days of cooling storage and the same result was found in the reduced glutathione (GSH) concentration at 24, 72, and 168 h of storage. There was a significant (p ≤ 0.05) decrease in malondialdehyde (MDA) concentration in the 400 µM resveratrol group than that in two other groups over the seven days of storage period. Cleavage and blastocyst rates following in vitro fertilization were significantly higher (p ≤ 0.05) in 400 µM resveratrol than other groups at 72 h for cooling storage period. In conclusion, addition of resveratrol in the extender can protect sperm head morphology, improve kinematic parameters and in vitro fertility, and reduce oxidative stress of ram spermatozoa during liquid storage at 5 °C.