Improving litter size by boar spermatozoa: Application of combined H33258/CTC staining in field trial with artificial insemination

Conventional semen analysis offers basic information on infertility; however, its clinical value in predicting fertility status is unclear. To establish an accurate diagnosis of male fertility, semen analysis under capacitation condition is necessary because only capacitated spermatozoa are capable of fertilizing oocytes. The objective of this study was to verify male fertility based on conventional semen analysis before and after capacitation, including the assessment of motility (%), motion kinematics, and capacitation status of spermatozoa. A computer-assisted sperm analysis system and chlortetracycline staining were applied to evaluate the motility parameters and capacitation status, respectively. To enable efficacy of the two methods for predicting fertility, correlation analysis was performed with the historic litter size. Our results showed that sperm motility (%), motion kinematics, and their variations before and after capacitation represented a statistical non-significant correlation with litter size. Litter size showed significant correlation with acrosome reaction (AR) after capacitation (r = 0.375), as well as differences (Δ) in AR (r = 0.333) and capacitated (B) pattern (r = -0.447) before and after capacitation. The overall accuracy of the assay for predicting litter sizes using the AR and differences (Δ) in the AR and B pattern was 70%. On the basis of these results, we propose that capacitation status of spermatozoa is a more reliable indicator for evaluating male fertility status compared to motility parameters. Therefore, we suggest that analysis of capacitation status in company with conventional semen analysis may accept to evaluate more accurate diagnosis or prognosis of male fertility.