title: Effects of extenders, cryoprotectants and freezing methods on sperm quality of the threatened Brazilian freshwater fish pirapitinga-do-sul Brycon opalinus (Characiformes).
abstract: The objective was to develop a suitable freezing method to cryopreserve Brycon opalinus (Characiformes) sperm. Extenders (NaCl and glucose at 325 and 365 mOsm/kg), cryoprotectants (dimethyl sulfoxide=dimethyl sulfoxide (DMSO) and methyl glycol=methyl glycol (MG)), equilibration times (15 and 30 min), thawing temperatures (30 and 60 °C), and straw sizes (0.5 and 4.0 mL) were tested. Sperm were frozen in a liquid nitrogen vapor vessel at -170 °C and subsequently stored in liquid nitrogen. Post-thaw sperm quality was always evaluated in terms of motility (expressed as percentage of motile sperm), duration of motility and vitality (eosin-nigrosin staining, expressed as percentage of intact sperm). The best freezing method was also tested for fertility and hatching (expressed as the percentage of fertilized eggs). Post-thaw sperm quality was highest when sperm were cryopreserved in Glucose 365 mOsm/kg and MG, after a 30-min equilibration and thawed at 60 °C for 8 s, of regardless straw size: 74±7% motile sperm, 47±4 s of motility duration, 69±3% intact sperm, 64±4% fertilization and 63±3% hatching. The freezing method developed in the present study was efficient and can be used to maximize larvae production for both aquaculture purposes and for conservational programs, since B. opalinus is a threatened species.
authors.affiliation: Department of Animal Science, Federal University of Lavras, UFLA, P.O. Box 3037, Lavras, Minas Gerais, 37200-000, Brazil. anatmviveiros@hotmail.com
authors.forename: A T M
authors.initials: AT
authors.lastname: Viveiros
authors.forename: L H
authors.initials: LH
authors.lastname: Orfão
authors.forename: A F
authors.initials: AF
authors.lastname: Nascimento
authors.forename: F M
authors.initials: FM
authors.lastname: Corrêa
authors.forename: D
authors.initials: D
authors.lastname: Caneppele
mesh_terms: D000818:Animals; D001938:Brazil; D060125:Characiformes / Q000502:physiology*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D017753:Ecosystem; D056727:Endangered Species; D005260:Female; D005298:Fertility; D005615:Freezing; D008297:Male; D010063:Ovum / Q000502:physiology; D055101:Semen Analysis / Q000662:veterinary*; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*
chemical_list: D003451:Cryoprotective Agents