Evaluation of fertility status of Murrah buffalo bulls in vitro using zona-free hamster eggs

Cryopreserved semen samples from 10 Murrah buffalo bulls were used for sperm penetration bioassay using zona-free hamster oocytes. The samples were evaluated for sperm motility, viability and acrosome integrity. Actively motile spermatozoa recovered by the swim-up technique were capacitated using calcium ionophore A(2 3 1 8 7). Mature female golden hamsters were superovulated with 50 IU PMSG followed 56 h later by 75 IU hCG. Cumulus mass, recovered by puncture of oviducts at the infundibulum region, was treated with 0.1% hyaluronidase and 0.1% trypsin to obtain zona-free oocytes. After coincubation of zona-free oocytes with capacitated buffalo spermatozoa, scoring was done as fertilization percentage and fertilization index. The correlation coefficients with conception rate were statistically significant with fertilization percentage (r = 0.588, P < 0.05) and fertilization index (r = 0.660, P < 0.01). However, conventional parameters like viability, motility and acrosome integrity showed poor correlation with conception rate.