Optimization of Method for Ultra-low Temperature Cryopreservation of Paramisgurnus dabryanus Semen

【Objective】The study was to optimize the method for ultra-low temperature cryopreservation of the semen of Paramisgurnus dabryanus.【Method】With the thawed sperm motility as the parameter, the experimental conditions were controlled, the best semen diluent and antifreeze were selected, and the volume fraction of antifreeze and the dilution ratio of semen were optimized.【Result】Among the five diluents, diluent Ⅳ was the most effective, with a frozen sperm motility of 35.5（±2.7）%. For the three antifreeze protectants, namely, glycerol（GLY）, methanol（METH）, and dimethyl sulfoxide（DMSO）, when treated with 5%（V/V）DMSO, the frozen sperm motility was 40.7（±2.5）%, significantly higher than that of the 5% GLY and METH treatments. Optimization of the DMSO volume fraction revealed that 10% final concentration of DMSO was more effective in protecting semen, with a frozen sperm motility of 54.6（±1.5）%. Based on the optimization of dilution Ⅳ and semen dilution, it was found that good results could be achieved when diluent IV was diluted with semen at a volume ratio of 3 ∶ 1, and the frozen sperm motility could reach up to 65.4（±2.3）%.【Conclusion】By setting the volume ratio of diluent Ⅳ to the semen as 3 ∶ 1 and a final concentration of 10% DMSO as antifreeze, the best results were obtained when the semen of P. dabryanus was cryopreserved at ultra low temperature.