Author : Kustono

Summary : The freezability of Murrah bull semen in tris-egg-yolk-citrate-glycerol (TYG), skim milk egg-yolk-citrate glycerol (SA-ECG), and glycine-egg-yolk-citrate glycerol (Gly-ECG) extenders using one, two, and three hours of equilibration time were studied. Extended semen were packed in 0.5 ml French straws, frozen in liquid nitrogen (-196 degree C), and stored for five months. Post-thawing motility of sperm 15 minutes after freezing were 31.8, 28.6 and 27.7 percent in extender TYG, SM-ECG, and Gly-ECG, respectively. Extended semen equilibrated for one, two, and three hours had post-thawing motility averages of 23.0, 31.6 and 33.5 percent, respectively. The average post-thawing motility for Bull 1 and Bull 2 were 28.64 and 30.1 percent, respectively. Highly significant (P<0.01) differences were found among treatments. Likewise, bull x extender interaction just after freezing on post-freezing motility was highly significant. Differences in post-thawing motility among the treatments where highly significant (P<0.01) interactions were observed on the following: bull x extender and bull x equilibration time during the second month of storage; and extender x equilibration time during the fourth month storage period. Based on the results, it can be concluded that TYG is superior to both SM-ECG and Gly-ECG in terms of post-thawing motility provided that high quality semen is used and that the semen was properly handled until they are frozen. It was further recommended that the extended semen, which will be deep-frozen undergo an equilibration period of not less than three hours.