The sensitivity of dourado (Salminus brasiliensis) spermatozoa to different cryoprotectant solutions was evaluated in three experiments. In experiment 1, semen was diluted, 1:10, in 12 solutions (four extenders x three cryoprotectants - dimethylsulphoxide (DMSO), methyglycol, or glycerol). Half of each sample was refrigerated for one hour while the other half was cryopreserved. Sperm motility was immediately assessed after dilution and after refrigeration in all samples, and after thawing in those cryopreserved in DMSO. In experiment 2, semen was diluted, 1:5, in five solutions containing DMSO, refrigerated, cryopreserved, and analyzed as in experiment 1. In experiment 3, semen was diluted, 1:5, in five solutions containing DMSO, cryopreserved and evaluated for motility and fertility. When semen was diluted 1:10, motility higher than 58% was observed in all samples refrigerated in DMSO and in NaCl-tris-methylglycol. Low motility was observed in samples refrigerated in the other combinations of methylglycol (5-32%) or glycerol (0-8%) and in those cryopreserved (16-20%). All samples diluted 1:5 yielded motility of 65-72% after refrigeration, and 45-66% after thawing (experiments 2 and 3). The hatching rates produced with cryopreserved semen, however, were lower (17-23%) compared to fresh semen (60%).
dourado; Salminus brasiliensis; extender; cryoprotectant; cryopreservation; fertilization
