Liquid Storage of Geophagus brasiliensis semen in the Presence of Different Extenders.

BACKGROUND: In order to preserve the genetic diversity of cichlid fish in gene banks, it is necessary to use certain extenders to maintain the integrity of spermatozoa cells during cooling. OBJECTIVE: To evaluate the effects of different extenders on the quality parameters of cooled semen of Geophagus brasiliensis. MATERIALS AND METHODS: Semen samples were collected from seven adult fish and diluted with five extenders: Beltsville Thawing Solution (BTS™), Hanks' Balanced Salt Solution (HBSS), Tris-glucose, Ginsburg's Fish Ringers, and Phosphate buffered Saline. All parameters were evaluated in fresh semen samples and after cooling at 4°C at 0, 24, 48, and 96 h to evaluate cell viability (membrane integrity, DNA, and mitochondrial functionality) and motility rate and weather motility. RESULTS: The BTS and Tris-glucose resulted in the best outcomes (P<0.05) in terms of membrane integrity assessments (35.1% and 30.9%, respectively), DNA integrity (71.6%; 75.7%), mitochondrial function (26.9%; 28.0%) and motility rate (8.6%; 8.6%), respectively, for semen cooled to 4°C for 96 h. However, the 48-h period motility after cooling in BTS was superior to all other treatments. CONCLUSION: BTS and Tris-glucose can be considered as the best extenders for the cold storage of Geophagus brasiliensis spermatozoa.

Use of amides as cryoprotectants in extenders for frozen sperm of tambaqui, Colossoma macropomum.

Amides were tested as cryoprotectants in comparison with glycerol and DMSO (more traditional cryoprotectants) for recovery of Colossoma macropomum (tambaqui fish) sperm. Milt was extended in Beltsville Thawing Solution, then frozen with the addition of 2%, 5%, 8%, or 11% of: (1) dimethylacetamide (DMA), (2) dimethylformamide (DMF), (3) methylformamide (MF), or with 5% glycerol or 10% dimethylsulfoxide. Fertilization rates were greatest (P<0.001) with amides; 8% DMF (91.6±1.3%), 5% DMF (88.9±1.6%), and 8% MF (83.0±1.6%), which did not significantly differ among themselves, when compared with glycerol (51.6±2.4%) and DMSO (61.9±3.1%). The best hatching rates (P<0.001) also occurred for 5% or 8% DMF and 8% MF (79.1±3.1, 87.6±1.5, and 74.8±3.0, respectively) and were also similar (P>0.05). For such treatments, both fertilization and hatching rates were similar (P>0.05) to those with fresh sperm (91.7±1.4 and 87.4±1.4, respectively). The best sperm motility across extenders (at least 55.7%) was with 5%, 8%, and 11% DMF (P<0.001). Those same treatments, along with 11% MF, provided the longest (P<0.001) period of motility (at least 1 min). The greatest sperm integrity (more than 54%) was with 5% and 11% MF and with DMA and DMF at all tested concentrations (P<0.001). The greatest (P<0.001) sperm viability (at least 31%) was for 5%, 8%, and 11% DMA, and with 8% and 11% MF, and also for DMF at all tested concentrations. Sperm DNA integrity was best (more than 50%) for 2%, 5%, and 8% MF and for DMA and DMF at all concentrations (P<0.001), whereas 2% DMA, 11% MF, 11% DMF, and the three amides at both 5% and 8% yielded the highest mitochondrial functionality (at least 44%; P<0.001); thus, 8% MF and both 5% and 8% DMF were the cryoprotectants with the best postthaw quality for C. macropomum sperm.