Abstract:
In an attempt to develop a gamete-recovery protocol for the northern hairy nosed wombat (Lasiorhinus krefftii), spermatozoa were removed from the cauda epididymides of four common wombats (Vombatus ursinus) and cryopreserved following a variety of prefreeze storage conditions. Spermatozoa stored for 72 h at 4�C within the testicle before cryopreservation tolerated the freeze?thaw procedure remarkably well, resulting in a higher post-thaw viability (% motile P < 0.01; rate of movement P < 0.01; % live P < 0.01) than sperm recovered on the day of post-mortem, stored in a test tube for 72 h at 4�C and then frozen. The effect of post-thaw dilution with Tris citrate fructose (TCF) diluent on the survival of epididymal common wombat spermatozoa was also investigated. Motility (P < 0.05), rate of sperm movement (P < 0.01) and the percentage of live spermatozoa (P < 0.05) were all significantly greater when spermatozoa were thawed and diluted immediately in TCF than when thawed without dilution. The present study also reports, for the first time, a successful pellet method of freezing wombat spermatozoa on dry ice; volumes of 0.25 and 0.5 mL resulted in higher post-thaw survival compared with 0.1-mL pellets.