The Effect of Saccharides on the Post-thaw Recovery of Cane Toad (Bufo Marinus) Spermatozoa

The effect of monosaccharides (glucose, fructose) and disaccharides (maltose, sucrose, trehalose) as diluents, in cryoprotective additives containing 15% (v/v) Me₂ SO or glycerol as cryoprotectants, were investigated on the recovery of sperm motility after cryopreservation of cane toad (Bufo marinus) spermatoazoa at low (≈ 5°C min^-1) and high cooling rates ≈ 35°C min^-1). The results show that: 1. recovery of percentage motility was higher with slow cooling than with high cooling rates (37.0 + 2.5%, 15.3 + 1.6%, P < 0.001, respectively), 2. disaccharides were more effective than monosaccharides in protecting spermatozoa with slow cooling (43.9 + 1.2%, 26.8 + 2.5%, P < 0.02, respectively), 3. glycerol was more effective than Me₂ SO with fast cooling (18.3 + 2.2%, 12.6 + 2.3%, P < 0.02, respectively), 4. trehalose with glycerol was the most effective cryoprotective additive with fast cooling (31.0 + 3.2%, P < 0.05), and 5. overall the recovery of degree (vigour) of motility (range, 1.9 - 3.2) was more resilient to cryopreservation than recovery of percentage motility (range, 8.9 - 51.5 %). Comparison of post-thaw percentage and vigour of sperm motility up to 24 minutes after activation showed disaccharides supported greater duration sperm motility than monosaccharides This result and the recovery of spermatozoa immediately after freeze-thaw, show the main effect of saccharides are as cryoprotectants and not as exogenous energy substrates.