Background: Frozen equine semen has lower fertility compared to cooled semen. Due to the difficulty to obtain equine oocytes, a heterologous zona pellucida binding assay (ZBA) is an alternative method to predict the fertilizing capability of equine frozen sperm. The rate of capacitated and hyperactivated sperm according to their motility characteristics were analyzed with a Computer Assisted Sperm Analyzer. We believe this report describes for the first time the in vitro hyperactivation induction and the heterologous ZBA to predict the fertilizing ability of frozen equine sperm.
Objective: This work aimed at developing an assay to evaluate the fertilizing ability of frozen equine sperm using a bovine ZBA with the use of an in vitro capacitation and hyperactivation media with procaine and calcium ionophore A23187, respectively.
Materials and methods: The sperm motility characteristics, intact and acrosome reacted sperm rates, and number of stallion sperm bound to the bovine ZP were calculated.
Results: The procaine group showed a hyperactivation motility pattern, although it improved ZP sperm binding similarly to the capacitation group.
Conclusion: The capacitation medium improved the IVF capability of frozen equine sperm, allowing the highest possibility of sperm-oocyte interaction.