Optimization of the process of cryopreservation of Beluga, Huso huso semen using various cryoprotectants

Currently, the research on cryopreservation of the reproductive cells plays great importance in the conservation of genetic diversity of many economically and ecologically valuable fish species. In this study, optimization of beluga (Huso huso) semen cryopreservation was carried out by testing four different cryoprotectants, i.e., 5% ethylene glycol, 10% and 3% dimethyl sulfide oxide, and 5% glycerol. Moreover, the effects of cryotube size (0.2 and 1.9 mL) and type (Eppendorf tube and polypropylene straws) on the effectiveness of semen cryopreservation were tested. The quality of beluga cryoconserved semen was assessed using a five-point Persov scale, including spermatozoa activity time. In this study, the use of a 3% DMSO cryosolution resulted in the best sperm motility (79%) and activity time (305 s) that were significantly (p < 0.05) higher when compared to other cryoprotectants: 10% DMSO (48.1% and 254 s), 5% ethylene glycol (21.4% and 152 s), and 5% glycerin (21.8% and 139 s). It was shown that the use of smaller cryotubes (0.2 mL) significantly (p < 0.05) increases sperm motility (78%), when compared to 1.9 mL cryotubes (50.1%). No significant differences (p > 0.05) in semen motility were observed between polypropylene straws and Eppendorf vials.