Evaluating the effects of different concentrations of glycerol and thawing temperatures in the process of ram epididymal spermatozoa cryopreservation

Cryopreservation of epididymal spermatozoa has an important role in the conservation programs of endangered domestic and wild animal species, as well as, maintaining the genetic potential of suddenly dead valuable males. The aim of the present study was setting up an optimum protocol for the cryopreservation of ram epididymal spermatozoa. Spermatozoa extracted from the cauda epididymis of slaugtherd rams were frozen in the extenders containing 2, 4 and 6 percent glycerol and were thawed at 37 and 65˚C. Post-thawing motility parameters were evaluated by CASA. The factorial ANOVA model were used to determine the statistical differences between the main effects of the glycerol concentrations, thawing temperatures and their interactions (concentration×temperature). Because a non-significant interaction was detected, the main effects (concentration and temperature) were interpreted. The effect of glycerol concentration on the all motility parameters and the effect of thawing temperature on the majority of motility parameters were significant (P<0.05). Among the glycerol concentrations, 2% had the lowest motility and 4% had the highest motility (P<0.05). Among the the thawing temperatures, thawing at 65˚C led to significantly better post-thawing motility than thawing at 37˚C (P<0.05). Finally, freezing ram epididymal spermatozoa in an extender containing 4 percent glycerol and thawing the frozen spermatozoa at 65˚C had the best outcome.