Effect of dilution rates and different concentration of dimethyl sulphoxide, methanol and ethylene glycol on motility parameters of Beluga (Huso huso) 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 cryoprotectant and effect of different dilution ratios on sperm motility percent and its motility duration after thaw. For this work dimethyl sulfoxide, methanol and ethylene glycol was used as cryoprotectant, each at concentration of 5, 10 and 20% were added to the extender (30mM Tris, 23.4mM sucrose, 0.25mM KCl, PH 8.0). Then, extender with 1:0.5, 1:1 and 1:2 mixture ratios of the extender and sperms collected and the sperm was frozen. In this study semen obtained from three Beluga males were used. Frozen sperms after 15 and 30 days were excluded from freezing. The results of the experiment showed that highest motility duration and the most motility percentage of post-thawed sperms after 15 and 30 days was related to the sperm with the concentration of dimethyl sulfoxide 10% and the dilution ratio of 1:1 (230.32±20.42 s and 23.41±2.60%; 218.20±18.10 s and 20.12±1.90%, respectively). Also minimum motility duration and the most motility percentage of post-thawed sperms after 15 and 30 days was related to the sperm with the concentration of ethylene glycol 20% and the dilution ratio of 1:2 (92.24±18.40 s and 9.20±1.30%; 65.37±19.80 s and 7.00±1.00%, respectively).