Cryopreservation of sterlet (Acipenser ruthenus) spermatozoa using different cryoprotectants

The present study examined the effectiveness of different cryoprotectan uses for cryopreservation of sterlet (Acipenser ruthenus) sperm. Four different cryoprotectans [dimethyl‐sulfoxide (DMSO), dimethylacetamide (DMA), ethyleneglycol (EG) and methanol (MET)] in concentrations of 5 and 10% in the extender media (30 mm sucrose, 1 mm KCl, 25 mm Tris–HCl pH 8.5) were used for the cryopreservation of sperm from five sterlet males. Percentages of motility, velocity, fertilization and hatching rate were measured. The highest post‐thawing motility was observed in sperm samples cryopreserved with 10% MET (46 ± 19%), 10% DMA (47 ± 18%) and 10% DMSO (45 ± 7%). Fertilization rate in the control (fresh sperm) was 69 ± 9% and the hatching rate 61 ± 8%. A higher hatching rate after cryopreservation was obtained with 10% MET (32 ± 17%) and 5% DMA (23 ± 3%) when compared to data obtained with 10% DMA (9 ± 5%), 5% MET and 5 and 10% DMSO, wherein the hatching rate was around zero. Our results demonstrate that DMA can be used for cryopreservation of sturgeon spermatozoa.