Redox potential in animal andrology: An experimental study on boar semen

Impaired seminal redox balance is a main factor that contributes to male fertility disorders and reduced sperm survival during storage. Although several methods are available to measure antioxidant and reactive oxygen species (ROS) levels, their cost and complexity limit their use in routine sperm analysis. Recently, assessment of oxidation-reduction potential (ORP) has emerged as a convenient and comprehensive method for evaluating seminal redox status. While the implications of seminal ORP in humans have been extensively explored, its use in other species is limited. In this study, we explored the relationship between boar seminal ORP and sperm quality and its dynamics during liquid preservation. We found that the ORP of the porcine ejaculate was lower than that of the seminal plasma, while both parameters were correlated with the total antioxidant capacity (TAC) of seminal plasma. Sperm concentration and seminal pH influenced the seminal ORP, with lower values observed in ejaculates with higher sperm concentration and pH. Notably, a more oxidative seminal environment (characterized by high ORP or low TAC) was correlated with high mitochondrial activity and sperm velocity in fresh samples, which might be explained by increased ROS production by sperm mitochondria. Our results also show that seminal ORP increased during three days of liquid storage, while the ORP of the extender did not change significantly during the same period. Our findings advance our understanding of the implications of redox status in porcine sperm biology and pave the way for the broader application of ORP measurement in animal andrology.