Effects of glycerol, equilibration time and antioxidants on post-thaw functional integrity of bovine spermatozoa directly obtained from epididymis

This work aimed to evaluate the effect of stabilisation times, glycerol concentration, and the catalase and superoxide dismutase supplementation of diluent on parameters of frozen-thawed spermatozoa from epididymis of Nelore bulls: Experiment 1: spermatozoa diluted in Tris-egg yolk with glycerol (3%, 5% or 7%) and stabilisation times (0, 2 or 4hr at 5 degrees C); Experiment 2: Tris-egg yolk only, Tris-egg yolk with catalase (CAT, 50 or 100Uml(-1)) or superoxide dismutase (SOD, 50 or 100Uml(-1)). Frozen-thawed spermatozoa were evaluated for kinetic parameters, plasma membrane and acrosome integrity, mitochondrial activity and IVF capacity. ALH and BCF were affected (p<.05) by glycerol at 3% after 4-hr equilibration time and 7% after 2-hr equilibration time. Glycerol 3% had lower (p<.05) iPM and iAc after 4hr. Glycerol 5% had greater (p<.05) hPMM after 4hr and iAc after 2hr than at 0hr. SOD 100Uml(-1) had lower (p<.05) linearity and wobble compared to control group. No was observed differences to fertilisation rate (p<.05) among groups. In conclusion, glycerol 5% in Tris-egg yolk extender for 4hr is suitable for the preservation of sperm kinetics and membrane integrity. CAT (50 and 100Uml(-1)) or SOD (50-100Uml(-1)) had no beneficial effects on sperm kinetics, plasma and acrosomal membrane integrity, mitochondrial activity or the capacity for IVF of frozen-thawed spermatozoa from epididymis of Nelore bulls.