Cooling and freezing protocols of pirapitinga (Brycon nattereri) semen were evaluated using semen diluted in 154mM NaCl, 200mM NaCl, Saad or BTS™, and cooled for seven days. Sperm motility was daily evaluated. Five extenders (277mM glucose, 154mM NaCl, 200mM NaCl, Saad and BTS™) were combined with two cryoprotectants (DMSO - dimethyl sulphoxide and methylglycol) to produce 10 cryosolutions. Semen was diluted in each cryosolutions, aspirated into 0.5ml straws and frozen. Sperm motility was evaluated after thawing (60°C, 8 sec). Then, semen was frozen in straws with different volumes (0.25 and 0.5ml), and thawed under different water-bath temperatures (50° and 60°C). Higher sperm motility (48%) was observed when semen was cooled in BTS™ for seven days. Post-thawing sperm motility above 68% was observed when semen was frozen in 154mM NaCl-methylglycol, BTS™-methylglycol, 200mM NaCl-DMSO or Saad-DMSO. There was no difference on sperm motility when semen was frozen in 0.25 or 0.5ml straws and thawed in 50° or 60°C water-bath. Thus, pirapitinga semen can be successfully cooled in BTS™ for seven days or frozen in 154 mM NaCl-methylglycol, BTS™- methylglycol, 200mM NaCl-DMSO and Saad-DMSO.
fish; extenders; cryoprotectants; cooling; cryopreservation
