A protocol for cryopreservation of spermatozoa of the fish Brycon orthotaenia

Abstract

protocol to freeze its spermatozoa to be used in artificial breeding programs aimed at preserving this species. Hand-stripped milt measured 2.0 ± 0.8 ml with a sperm concentration of 14.4 x 109 spermatozoa/ml, and a spermatocrit of 40.2 ± 9.6%. We used post-thaw sperm motility to evaluate the effects of the freezing protocol on the spermatozoa. To measure sperm motility of fresh samples, we used a two-step dilution procedure. Fresh spermatozoa remained immotile when the milt was diluted in a 150- or 200-mM NaCl solution, but motility rates rose when the milt was diluted in NaCl solutions of lower osmolality. Peak motility occurred in a 25- and 50-mM NaCl solutions (88 % motile spermatozoa and>50 s duration of motility). Concentrations of 5%, 10%, and 15 % of DMSO, ethylene glycol, and propanediol did not significantly induce changes in motility rate of