Resfriamento e criopreservaÃÃo do sÃmen de curimba Prochilodus lineatus (Valenciennes, 1836) / Semen cool storage and cryopreservation of curimba Prochilodus lineatus (VALENCIENNES, 1836)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Curimba (Prochilodus lineatus) is a species of native fish of the Grande river. This species is commercially important for being supplied as food to other ecological or commercial species, of interests, during the fingerling production. Moreover, it is protein source of high quality for marginal and devoid populations. The objective of this work was to develop a protocol of semen preservation of curimba through cooling 4-6ÂC and cryopreservation storage. This works was carried out at the Fish Culture Unit of Energy Company of Minas Gerais (CEMIG), Itutinga-MG. For chilling storage, semen was diluted (1:10, v/v, semen: total volume) in saline solutions (NaCl 0.9%, NaCl 1.2% or NaCl-tris) or in glucose-based solutions (glucose 5%, BTS 5% or M III 6%). BTS contains glucose, sodium citrate, EDTA, gentamycin sulfate, NaHCO3 and KCl, and M III contains the same chemical composition of BTS except KCl. One semen aliquot was kept undiluted and was used as control. All samples were stored in open 5-mL test tubes at 4â6ÂC and motility was evaluated after 0, 1, 2, 3, 4, 5 and 6 days of storage. Sperm motility was subjectively estimated after addition of activation medium (NaCl 0.29%). For semen cryopreservation, two experiments were carried. In experiment 1, eight freezing medium were prepared using a combination of four extenders (NaCl 0.9%, glucose 5%, BTS 5% and M III 6%) and two cryoprotectants (dimethyl sulphoxide - DMSO and methylglycol). Semen was diluted (1:10, v/v, semen: total volume) in each freezing medium, aspirated into 0.5-mL straws (n=3 per medium), transferred to a nitrogen vapor container (Taylor-Warton, CP 300) at -170ÂC and then stored in liquid nitrogen. Sperm motility was subjectively evaluated after thawing at 60ÂC-water bath for 8 s. To activate sperm motility, four activating medium (distilled water, NaCl 0.15%, NaCl 0.29% and NaHCO3) were tested. Then, to evaluate the effect of straw size (0.5 and 4.0 mL) and thawing temperature (30 and 60ÂC), semen was frozen in glucose-methylglycol medium using the same method as described on experiment 1. Post-thaw sperm motility was subjectively estimated after activation with NaCl 0.29%. On chilling storage, motility of only 4% was observed on undiluted semen after 2 days at 4-6 ÂC. Curimba semen diluited in BTS 5% or in M III 6% maintained motility above 50 % for as long as 5 days at 4-6ÂC. This results show that an extender is necessary to increase semen time storage. For cryopreservation, in experiment 1, there was an interaction among extenders, cryoprotectants and activation media. All samples cryopreserved in a medium containing NaCl 0.9% as extender, produced low post-thaw sperm motility, compared to the other extenders. Samples cryopreserved in glucose combined with methylglycol produced higher post-thaw sperm motility, compared to samples cryopreserved in glucose combined with DMSO. The four activating medium tested produced similar post-thaw motility in all extender-cryoprotectant combinations, except when BTS was used as extender and distilled water was used as activating medium. There was no difference on semen cryopreserved in 0.5- or 4.0-mL straw or thawed in 30Â or in 60ÂC.

ASSUNTO(S)

fish prochilodus zootecnia curimba peixe resfriamento cryopreservation cool storage sÃmen criopreservaÃÃo semen curimba prochilodus

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