Optimization of the in vitro fertilization protocol for frozen epididymal sperm with low fertilization ability in Ban—A native Vietnamese pigs.

Abstract: The aim of the present study was to improve the penetration during in vitro fertilization (IVF) of a frozen lot of epididymal sperm with a notoriously low fertilization ability of a Ban boar which is a native Vietnamese breed by optimizing different parameters of the IVF system. In Experiment 1, we determined that Pig‐fertilization medium was superior medium to Tyrode's albumin lactate pyruvate‐polyvinyl alcohol medium for IVF and defined the optimum the sperm concentration (1 × 10⁶ sperm/ml). In Experiment 2, we clarified that partial removal of cumulus cells from cumulus‐oocyte complexes by hyaluronidase treatment before IVF enhances sperm penetration, whereas complete cumulus removal reduces penetration. Finally, in Experiment 3 the elevation of concentration of caffeine in Pig‐fertilization medium from 2 to 5 mmol/L and the prolongation of the co‐culture of gametes from 3 to 5 hr significantly increased the total penetration rate from 15.2% to over 50%. In conclusion, the combination of partial oocyte denudation, an elevated caffeine concentration in Pig‐fertilization medium and an extended interval of IVF with using an optimized sperm concentration was a potent way to improve the fertilization results for a frozen epididymal Ban sperm lot with low fertility. [ABSTRACT FROM AUTHOR]