Cryopreservation of Water Buffalo, Bubalus bubalis (L.) Spermatozoa Using Ethylene Glycol: Effects of Equilibration Time, Thawing Temperature and Time on Post-thaw Motility Rate

The study was conducted to determine the optimal equilibration time, thawing temperature and thawing time on the post-thaw motility of buffalo spermatozoa frozen using ethylene glycol as the cryoprotectant in the diluent. Collected semen samples from three different bulls were all diluted with a Tris-raffnose-egg yolk extender with 7% ethylene glycol. The samples were then subjected to three different equilibration times (i.e., 20, 40 and 60 min) at 5 oC. After the equilibration time has been reached, the straws were suspended in liquid nitrogen vapor for 7 min. (-126 oC) and then stored in liquid nitrogen (-196 oC) for 7 to 14 days until thawed. The thawed samples were then subjected to different thawing temperatures and thawing times. The study showed that the semen subjected to 20-min equilibration time had a comparable level of post-thaw motility with those equilibrated for 60 min. However, those subjected to 40-min equilibration time had a signifcantly lower (p Key words: Bubalus bubalis, cryoprotectant, equilibration, freezing, spermatozoa, thawing, water buffalo