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 [dimethylsulfoxide (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.