Effects of proanthocyanidin on freezability of ram sperm

The aim of this study was to investigate the effects of proanthocyanidin at different concentrations on post-thaw spermatozoal parameters, oxidative stress, and DNA damage in the semen diluent of Sönmez breed rams. Ejaculates were collected once a week from three mature rams using artificial vagina and repeated six times. The ejaculates were divided into five groups, including a control group with no antioxidant and four groups with different concentrations of proanthocyanidin (10 µg/ml, 25 µg/ml, 50 µg/ml, and 100 µg/ml) in the semen diluent to obtain 150 x 10^6 spermatozoa per ml. After equilibration for 3 hours at 5°C, the diluted samples were frozen in 0.25 ml straws and stored in liquid nitrogen vapor. The subjective motility of the group with 10 µg/ml proanthocyanidin was significantly higher (P<0,05) than that of the control and other groups. A decrease in abnormal spermatozoa rates was found to be statistically significant (P<0,05) in the group containing 10 μg/ml proanthocyanidin compared to the control group, in terms of both head and tail abnormalities. There was also a significant decrease in the mid-piece of spermatozoa in the groups containing 10 and 25 μg/ml proanthocyanidin. The H+/E- ratio significantly increased (P<0,05) in the group with 10 µg/ml proanthocyanidin compared to the control group. The tail length significantly decreased (P<0,001) in the groups with 10 µg/ml and 25 µg/ml proanthocyanidin, the tail DNA significantly decreased (P<0,001) in the groups with 10 µg/ml, 25 µg/ml, and 50 µg/ml proanthocyanidin, and the tail moment significantly decreased (P<0,001) in all antioxidant-treated groups compared to the control group. The total oxidant status significantly increased (P<0,05) in the groups with 10 µg/ml, 25 µg/ml, and 100 µg/ml proanthocyanidin compared to the control group. In conclusion, the results of this study indicated that 10 µg/ml proanthocyanidin provides the best protection for ram semen during storage in terms of sperm motility, abnormal and dead/live spermatozoa ratios, membrane integrity, and DNA damage. Keywords: Ram, Sperm, Proanthocyanidin, Antioxidant, Cryopreservation