This study was conducted to evaluate the effects of different diet energy levels on animal performance. Specifically, this investigation examined the reproductive and histological aspects of the liver and gonads of female silver catfish (Rhamdia quelen). These fish were fed for 210 days with diets containing 30% digestible protein (DP) and digestible energy (DE) that corresponded to 11.93, 12.98, 14.03, 15.07 and 16.12 MJ of DE kg−1. The initial and final lengths, weights, and weight gains, the visceral, gonadal, and hepatosomatic indices, and the histological parameters hepatocytes area and gonadal stages were evaluated. In the reproductive season, the fish were submitted to an artificial reproduction protocol and the percentage of spawning females and their relative and absolute fecundity were evaluated. DE did not affect reproductive or animal performance aspects (P > 0.05). Cytoplasmic vacuoles in hepatocytes were observed in higher DE levels. Thus, female Rhamdia quelen can be fed a diet of 30% DP with 11.93 MJ of DE kg−1 without reproductive or performance losses.
For the first time was characterized the semen of Pimelodus britskii, hormonally induced and noninduced induced, during the reproductive period. The experiment 1 was conducted with 12 fish per month, divided into: (i) induced with Carp Pituitary Extract (CPE), and (ii) without hormonal induction (testes macerated). The experiment 2 was conducted, with 30 fish, divided into groups for comparison of different doses of CPE and human Chorionic Gonadotrophin (hCG; T1: control; T2: 3.0 mg kg À1 CPE; T3: 0.5 mg kg + 3.0 mg kg À1 CPE; T4: 0.5 mg kg À1 + 7.0 mg kg À1 CPE; T5: 200 UI kg À1 hCG), the same fish were used every month, and the semen was collected by abdominal massage. In both, experiments were assessed the sperm motility and velocity by means of the CASA software. In experiment 1, the concentration of spermatozoids was significantly increase by application of CPE compared untreated males. The volume and motility decreased gradually until the end of the experiment, the highest values were recorded for treatment induced (0.49 AE 0.25 mL and 62.18, respectively). The same occurred to Gonadosomatic Index, showing the smallest value at the end of the reproductive period. The fish from experiment 2 released reduced volume of watery semen (0.1 mL). The values of sperm concentration, motility velocity decreased gradually throughout the months. For P. britskii, the reproductive period influenced the production and sperm quality. Despite small seminal volume released the dose of 7.5 mg kg À1 of CPE proved effective.
The study's aim was to evaluate the sperm movement in the semen of Rhamdia quelen, cryopreserved at different times of exposure to nitrogen vapor, besides different equilibration times and with different concentrations of methanol, and in thawed semen kept at 25ºC for different periods of time. Three distinct experiments were carried out. In the first experiment, fresh semen aliquots were diluted in a solution containing 5% D-Fructose, 5% milk powder (Nestle®, Ninho Fortificado®) and 10% methanol, filled into 0.25 mL straws and immediately kept in nitrogen vapor by 0,5; 1.0; 4.0; 8.0; 12.0 and 18.0h. After these times, the straws were transferred to the liquid nitrogen (-196°C). After 72 h, the semen was thawed by immersing the straws in water at (25 ° C) for 10 seconds. The sperm activation was evaluated by diluting the thawed semen in distilled water in the proportion of 1:250 (semen:activating solution; v/v). Motility and spermatic velocity in thawed semen were measured using the CASA system. In the second experiment, the fresh semen was diluted in solutions with glucose and powdered milk (Nestle®, Ninho Fortificado®) and 5.0; 7.5; 10.0; 12.5% methanol. Immediately after, it was filled into 0.25mL straws and kept at 25ºC by equilibrium times corresponding to 0, 20, 40 and 60 minutes. Subsequently, part of the straws was used for spermatic evaluation before cryopreservation and others were submitted to cryopreservation in nitrogen vapor for 30 minutes and after transferred to liquid nitrogen (-196°C). The processes of thawing and sperm evaluation were performed as described above. In the third experiment, the cryopreserved semen was thawed and kept at 25°C for 0.0; 7,5; 15,0; 22.5 and 30.0 minutes. After each time, the spermatic movement was evaluated as described above. The exposure time of straws to nitrogen vapor and the kept time of the thawed semen at 25ºC did not affect (p > 0.05) the sperm movement. On the other hand, methanol concentrations and equilibrium time (p < 0.05) influenced the spermatic movement interactively both, before and after cryopreservation. The best results were achieved when the semen was cryopreserved immediately after dilution. The cryopreservation of Rhamdia quelen semen can be successfully performed when the semen is diluted in a solution containing 5% D-Fructose, 5% milk powder and 11.66% of methanol and immediately filled into
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