Characteristics of Cryopreserved Spermatozoa from a Holstein-Friesian Bull Thawed at Different Temperature <Research Notes>

The present study was undertaken to examine the viability, motility and morphology of spermatozoa that were frozen-thawed at different temperature followed by the storage at 4ºC until 10 hours under the condition of tropical area. The frozen semen derived from a Holstein-Friesian bull with the egg-yolkbase extender was thawed at 23ºC or 37ºC for 30 seconds or 15 seconds, respectively, and kept at 4ºC. Viability, motility and damage of acrosomal cap in sperm were assessed every 2 hours after thawing. The sperm viability just after the refrigeration at 4ºC was not different between the groups. Besides, only 5% difference was found in the viability between the groups from 2 to 10 hours after thawing. On the other hand, the sperm had a fast progressive movement until 6 hours post-thawing. Only 2% or less sperms showed the damage of acrosomal cap in both groups. This value did not rise with keeping the semen at 4ºC until 10 hours in both groups. In conclusion, the thawing at 23ºC for 30 seconds does not have detrimental effects on the viability, motility, and morphological change of sperm. This suggests that the semen thawed at 23ºC can keep the quality at 4ºC for 6 hours.