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The aim of the present study was to evaluate induced reproduction in Colossoma macropomum females at the beginning of the reproductive period and 75 days after the first spawning in which reproduction was induced. The experiment was conducted in Nova Mutum, MT, Brazil. Eight 4-year-old C. macropomum females with an average body weight of 6.7 ± 2.4 kg were used. Hormonal induction was performed at the beginning of the reproductive period and repeated 75 days after the first spawning. The following variables were then evaluated: weight of released oocytes, production index, absolute fecundity, oocyte diameter, fertilization rate, and hatching rate. Of the eight females that spawned during the first hormonal induction, three (37.5%) spawned again 75 days after the first spawning. Two females died after the first induced spawning. None of the means of the evaluated variables differed between the two induced spawnings, except for fertilization rate, which was greater ( P  <  0.05) with the first spawning (88.8 ± 6.1%) than in the second (74.1 ± 10.4%). The results of the present study indicate that C. macropomum females can reproduce again 75 days after a first induced spawning. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the efficiency of the hormonal inducers Ovopel ® and carp pituitary extract (CPE) for induction of reproduction in Colossoma macropomum females. The treatments were CPE at the dose of 5.5 mg/kg divided into two applications (10%; and 90% after 12 h) and Ovopel ® at doses of 0.2 and 0.4 pellet/kg body weight in a single application. Eight replicates were used in each of the three treatments, totaling 24 experimental units. The females spawned when treated with the 0.2 pellet of Ovopel ® (100.0%), 0.4 pellet of Ovopel ® (62.5%), and CPE (87.5%), but there were no significant differences among the treatment groups in spawning rate. When there was treatment with Ovopel ® spawning occurred with greater ( P  < 0.05) degree-hours (average water temperature × number of hours until spawning; 0.2 pellet: 417.7; 0.4 pellet: 412.3) in relation to the CPE treatment (268.9). The total oocyte weight was similar when there was treatment with Ovopel ® (0.2 pellet: 832.3 g; 0.4 pellet: 798.9 g) and CPE (688.3 g). By contrast, the production index was greater ( P  < 0.05) with the Ovopel ® treatments (0.2 pellet: 8.8%; 0.4 pellet: 9.0%) as compared with CPE (6.7%). Fertility and hatching rates were similar among the treatment groups. Ovopel ® and CPE are efficient in induction of reproduction in C. macropomum females. Of the two Ovopel ® treatments assessed in this study, the dose of 0.2 pellet/kg body weight is sufficient for effective induction of reproductive processes. [ABSTRACT FROM AUTHOR]

This study aim was to verify whether milt quality of male Leiarius marmoratus is maintained among successive samples collected during the same reproductive period. Ten reproductively mature males were used to evaluate four successive sperm samples collected at 10-day intervals. For these collections, seven males were injected with carp pituitary homogenate (CPH) at a dosage of 3.0 mg/kg body weight, in two applications (30% and 70%), at an interval of 10 h. The other three males were administered only saline (control). Injection with CPH or saline occurred prior to each of the four collections. Only one male from the control group released a small volume of milt (0.33 mL), and only during the first collection period. Of the seven males treated with CPH, five released milt during all four collections. Milt volume of the first sample collected (0.63 mL) did not differ from that of other samples (0.59–1.38 mL; P > 0.05). Sperm concentration was greater in the first samples collected (1.98 × 109 spermatozoa/mL) compared to the other samples (0.35 × 109 at 0.92 × 109 spermatozoa/mL; P < 0.05). Sperm motility, curvilinear velocity, straightness, and morphological normality did not differ among the consecutive samples (P > 0.05). Average path velocity, straight-line velocity, oscillation, linearity, progression, and membrane integrity decreased slightly in the samples collected subsequent to the first sample (P > 0.05). In conclusion, milt quality decreased among successive collections; however, quality of all samples from all collections was sufficient for use for fertilization of oocytes. • Leiarius marmoratus males can reproduce more than once in the same reproductive period. • Males need to undergo hormonal stimulation. • L. marmoratus maintains the spermatozoa production capacity across successive reproductive events. [ABSTRACT FROM AUTHOR]

• Buserelin acetate induces the reproduction of tambaqui females. • Buserelin acetate can replace carp pituitary extract in the reproduction of tambaqui. • The reproduction of tambaqui with buserelin acetate maintains the quality of oocytes. The aim of this study was to evaluate induced reproduction in tambaqui females using buserelin acetate as compared with the traditional treatment regimen with carp pituitary extract (CPE). Reproductive traits of females with a body weight (BW) of 8.47 ± 1.52 kg were evaluated in ten females treated with buserelin acetate at the dose of 0.5 mL/kg BW, in a single application, and in ten females treated with CPE at the dose of 5.5 mg/kg BW, in two applications (10 % and 90 %, with a 12-h interval between applications). Spawning rate did not differ between the females treated with buserelin acetate (40 %) and CPE (40 %). Weight, fertilization rate and hatching rate did not differ between the two treatment groups. Degree-hours (determined as the average temperature multiplied by time, in hours, for spawning after the treatment with the second dose of CPE and after the single treatment with buserelin acetate) for spawning and number of oocytes per gram of gametes collected were greater (P < 0.05) in the females treated with buserelin acetate than in the females treated with CPE. Production index, absolute fecundity and relative fecundity were greater (P < 0.05) in the females treated with CPE. The hormone buserelin acetate promotes reproduction in tambaqui females with there being a similar spawning rate and oocyte quality, however, lesser production indices and fecundity than when there is the conventional treatment regimen imposed with carp pituitary extract. [ABSTRACT FROM AUTHOR]