Effect of different cryoprotectant and dilution rates on quality of stellate (Acipenser stellatus) post-thawed sperm

Cryopreservation is as an effective way to prevent species extinction risk. In this study, we have investigated the protective effect of different concentrations of dimethyl sulfoxide and ethylene glycol as cryoprotectant and effect of different dilution ratios on sperm motility percent and its motility duration after thaw. For this work dimethyl sulfoxide and ethylene glycol was used as cryoprotectant, each at concentration of 5, 10 and 20% were added to the extender. Then, extender with 1:0.5, 1:1, 1:2 and 1:5 mixture ratios of the extender and sperms collected and the sperm was frozen. In this study semen obtainad from four stellate males were used. Frozen sperms after 20 and 40 days were excluded from freezing. The results of the experiment showed that the between various treatments dilution with different concentrations of dimethyl sulfoxide and ethylene glycol on motility duration and motility percentage of stellate post-thawed sperms after 20 and 40 days of freezing were significantly different in treatments (P<0/05). highest motility duration and the most motility percentage of post-thawed sperms after 20 and 40 days was related to the sperm with the concentration of dimethyl sulfoxide 10% and the dilution ratio of 1:1 (253.00±24.81 s and 36.51±3.20%; 234.36±23.70 s and 27.50±2.12%, respectively).