Effects of oligomeric proanthocyanidins on quality of boar semen during liquid preservation at 17 °C.

The use of antioxidants is an important aspect in the preservation of boar semen. Oligomeric proanthocyanidins (OPC) are an effective natural antioxidants that scavenges free radicals and reactive oxygen species (ROS). This study was designed to investigate the antioxidative effect of OPC on boar semen quality during liquid preservation at 17 °C. The effects of different concentrations of OPC on sperm quality variables, antioxidant effects and fertility were analyzed in this experiment. Semen collected from six Guanzhong-Black boars and was diluted with Beltsville thawing solution (BTS). During the process of liquid preservation at 17 °C, the variables assessed were measured and analyzed every 24 h. The addition of OPC improved boar sperm motility, acrosome integrity, membrane integrity, and mitochondrial membrane potential as compared with that of the control group (P <  0.05). Meanwhile, malondialdehyde content (MDA) and ROS content was less after adding OPC, thereby improving the total antioxidant capacity (T-AOC) (P <  0.05). Different concentrations of OPC have different degrees of protective effects on boar semen quality. The results indicate that 50 μg/mL of OPC was the optimum concentration, and that the conception rate, litter size, and survival rate increased at this concentration as compared with that of the control group (P <  0.05). In summary, the addition of OPC to BTS diluents can improve the quality of boar semen at 17 °C during liquid preservation. Further research is needed to understand the mechanism by which OPC provides protection to boar semen during preservation in vitro.