Soluções ativadoras mais indicadas para a reprodução de piracanjuba Brycon orbignyanus e grumatã Prochilodus vimboides utilizando sêmen fresco ou criopreservado

Abstract

The conditions of extracelular enviroment, ionic concentration, pH, osmolality and temperature, makes effect on sperm activation and sperm quality. The objective of this study was to determine the effect of diferents activating solutions on the sperm quality and fertilization rate of the fresh sperm and cryopreserved sperm of piracanjuba Brycon orbignyanus (n=10) and grumatã Prochilodus vimboides (n=8). Was used 3 activation solutions with ions NaCl, KCl, CaCl2 (150 mOsm kg -1 ) and 3 solutions without ions glucose (150 mOsm kg -1 ), water reverse osmosis (RO) (~ 0 mOsm kg -1 ) and tank water (TW) (B.orbignyanus 139 mOsm kg -1 and P.vimboides 114 mOsm kg -1 ). After hormonal treatment with carp pituitary extract was collected the semen of males and the oocytes of females. In the experiment 1 the parameters of motility rate (%), motility quality score (1-5) and motility duration (seconds) of the fresh sperm were determined using a subjective form. Other aliquot of the semen from each male was used to fertilize oocytes from a one famale, the gamets were activated with solutions and evaluated the fertilization rate and hatching rate. In experiment 2, the semen was cryopreserved using methyl glycol as a cryoprotectant and as externders BTS ® 5% - 325 mOsm kg -1 (B.orbignyanus) and glucose 5% - 325 mOsm kg -1 (P.vimboides). The diluted sperm loaded into 0.5 mL straws which were frozen in a nitrogen vapor vassel and stored in a liquid nitrogen vassel. The straws (3 male -1 ) were thawed in a water bath at 60°C for 8 seconds and activated with diferents solutions, the parameters of motility rate and as curvilinear velocity (VCL), straight line (VSL) and average path (VAP) of the post-thaw were determined using a Computer-Assisted Sperm Analyzer (CASA). The data were tested for significant differences using ANOVA one-way and after SNK 5% test. In experiment 1 a higher average of the subjective parameters in fresh semen of B. orbignyanus was observed when the samples activated by the solution based on KCl, a solution based on calcium showed the lowest values. A higher value fertilization rate was observed when a gamets activated with TW and the lowest activated with CaCl2, was no statistical difference between the solution on hatching rate. In fresh sperm of P. vimboides the highest values were observed using glucose solution and the lowest when used CaCl2. The higher values of fertilization rate e hatching rate were observed in glucose or RO, the lowest were KCl or CaCl2. In the experiment 2 the samples post-thaw of B.orbignyanus activated with TW or RO showed the highest values for motility, the highest values of VCL, VSL and VAP were observed when activated with glucose compared to the samples activated with CaCl2. The highest values for fertilization rate and hatching rate were observed when used non-ionic solutions. The post-thaw of P. vimboides when activated with glucose solution presented the highest values of motility and velocities VCL and VSL compared when used KCl and CaCl2 with agent activator. The highest values of fertilization rate were observed using glucose or RO compared an ionic solution. The higher hatching rate value was observed on gametes activated with RO and the lower activated with NaCl. For the activation of fresh and cryopreserved semen of B.orbignyanus, the non-ionic activators must be used to obtain the best seminal quality and better rate of fertilization and hatching. The glucose solution (150 mOsm kg -1 ) and RO are the most suitable activators for fresh and cryopreserved semen in order to obtain the best seminal quality, fertilization rate and haching of P.vimboides.