Comparison of post-thaw sperm motility after freezing in liquid nitrogen with protective media of either glycerol or glycerol-egg-yolk-citrate

Thirty semen samples with a mean prefreezing motility of 70.4% were frozen for 1 month in liquid nitrogen by means of a modified Barkay's method and with either glycerol or glycerol-egg-yolk-citrate (GEYC) as protective media. The post-thaw motility was found to be 37.9% and 30.7% and cryosurvival rate (CSR) was 54.6% and 44.4%, respectively - the difference being significant (P < 0.05). When samples achieving at least 40% of post-thaw-motility (PTM) in either medium were selected, the mean prefreezing motility increased to a 71.6%, and the PTM and the average CSR were 44.1% and 62.2% and 35.5% and 50%, respectively, when either glycerol or GEYC was used. It appears that glycerol alone is superior to a mixture of GEYC for cryo-preservation of sperm if the technique mentioned above is used and PTM is a criterion for sperm quality.