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ABSTRACT The use of carp pituitary extract (CPE) in fish reproduction may have drawbacks, whereas analogues of mammalian (aGnRHm) or salmon (aGnRHs) gonadotropins containing dopamine inhibitor (DI) may offer greater advantages. The objective of this study was to evaluate the effect of different hormone inducers on the reproduction of Prochilodus brevis males. A total of 44 specimens of P. brevis were divided into six groups, namely, CPE 4.0 mg; saline solution 1.0 mL; aGnRHm + DI 0.3 mg and 0.5 mg; and aGnRHs + DI 0.25 mL and 0.35 mL kg-1 of live weight. The number of ejaculates, seminal volume, curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), sperm morphology and concentration, and membrane and DNA integrity were determined. Sample normality was examined using the Shapiro-Wilk test, and homogeneity using the Levene test. Analysis of variance (ANOVA) was conducted, followed by Tukey's test to compare means, with statistical significance set at p < 0.05. Notably, all fish induced with CPE 4.0 and aGnRHm + DI demonstrated ejaculation, yielding a greater seminal volume. Sperm concentration under aGnRHs + DI 0.35 exceeded that with aGnRHm + DI 0.3 and CPE 4.0. Regarding velocity, aGnRHm + DI 0.3 outperformed aGnRHs + DI 0.35 in VCL, while aGnRHm + DI 0.3 and 0.5 and aGnRHs + DI 0.25 led to higher VSL than aGnRHs 0.35. Additionally, VAP was elevated under aGnRHm + DI 0.3 and CPE, in contrast to aGnRHs + DI 0.35. Improved sperm morphology was observed with aGnRHm + DI 0.5 and aGnRHs + DI 0.25 compared to aGnRHm + DI 0.3. The remaining parameters did not differ significantly.

To assist the reproductive management of tambaqui (Colossoma macropomum) males in laboratory and commercial fish farming, a linear regression model was obtained from concentration curves using the spectrophotometric method. Twenty-two tambaqui males with an average age of three years old were selected and divided into two groups containing 11 animals each. Both groups alternately received a single dose of carp pituitary extract (CPE; 2.0 mg/kg body weight, intracoelomic). Sperm was collected 14 h after hormonal treatment and diluted (1:4000; sperm:formaldehyde saline). The concentration was estimated by counting spermatozoa in a Neubauer chamber and by using a spectrophotometer (λ=540 nm). Individual sperm concentration ranged from 11.40 to 71.13 × 109 sperm/mL. The degree of transmittance ranged from 62.1% to 95.0%. There was a significant correlation (r2 = 0.966; p < 0.0001) between sperm concentration analyzed in a Neubauer chamber and transmittance at 540 nm. Analysis by spectrophotometry and the prediction provided by the equation Y=100.293 – 0.509X proved to be an efficient and fast method for estimating sperm concentration in tambaqui and can be used in routine procedures in artificial fish reproduction laboratories. Keywords: fish; reproduction; semen.

The work aimed at determining the effects of applying different blends between liquid molasses and agricultural limestone on water quality and growth performance of Nile tilapia juveniles, Oreochromis niloticus. The study employed 24 indoor tanks of 100 L and 24 outdoor tanks of 250 L. Four control groups were set up (no product applied, only molasses, only limestone, molasses-limestone blend with 48% limestone but no fish) and two experimental groups (molasses-limestone blends with 32% and 48% molasses), with four replicates each. Over 11 weeks, the water quality was monitored systematically. The 24-h cycle monitoring of temperature, pH, specific conductance, dissolved O2 and total alkalinity were carried out at the 8th week. The blends between molasses and limestone accelerated the dissolution rate of the agricultural limestone in water. The blend containing 48% molasses led to greater increases in water alkalinity and pH in relation to tanks with only limestone applications. However, the molasses-limestone blend applications impaired the Nile tilapia growth performance, especially in the outdoor tanks. While the fish yield was 25.1 g m-3 day-1 in the molasses outdoor tanks, it was equal to 22.8 g m-3 day-1 in the molasses (32%)-limestone units (P

The present work aimed at assessing the possibility of compensating the notorious deficiencies of bioflocs in lipids by supplementing the tilapia commercial diet with soybean oil. In the positive control, there was no feeding restriction nor dietary supplementation with soybean oil. In the experimental treatments, the commercial diet was restricted by 25% over the positive control level. In the negative control tanks, there was feeding restriction and the artificial diet had no oil supplementation. In the experimental tanks, soybean oil was mixed daily with the commercial diet at the levels of 0.6%, 1.2 and 2.4%. Additionally, there were fed-restricted tanks that received a daily supplementation of 1.2% soybean oil mixed with dry molasses, and not with the commercial diet. In general, only the restriction of the commercial diet affected the water quality. The supplementation of the artificial diet with soybean oil up to 2.4% has not improved the proximate composition of bioflocs, nor the fish growth performance. It was concluded that the strategy of supplementing the Nile tilapia juveniles’ commercial diet with increasing levels of soybean meal, in BFT tanks submitted to 25%-feeding restriction, was not capable of avoiding the fish growth performance deterioration.

O presente estudo teve por objetivo determinar os efeitos da suplementação da ração balanceada de juvenis de tilápia do Nilo (peso médio inicial = 2,76 ± 0,06 g), submetidos à restrição na oferta de alimento artificial em tanques BFT de cultivo (18 juvenis/tanque 100 L), com DL-metionina, sobre a qualidade da água, composição dos bioflocos e desempenho zootécnico. Os tratamentos experimentais foram constituídos por dois grupos controle: 1 – sem restrição alimentar, sem suplementação com metionina; 2 – com restrição alimentar de 25%, sem suplementação com metionina. Os quatro tratamentos experimentais foram os seguintes: 1 – restrição alimentar de 25%, suplementação da ração com 0,5% de DL-metionina misturada à ração; 2 – restrição alimentar de 25%, suplementação da ração com 1,0% de DL-metionina misturada à ração; 3 – restrição alimentar de 25%, suplementação da ração com 2,0% de DL-metionina misturada à ração; 4 – restrição alimentar de 25%, suplementação do melaço em 1,0% de DL-metionina. A suplementação da ração balanceada com DL-metionina não afetou a qualidade da água de cultivo de juvenis de tilápia do Nilo, em tanques BFT, nem a composição centesimal do bioflocos. Após 8 semanas, o ganho em peso corporal dos peixes mantidos nos tanques com restrição alimentar e suplementação da ração com 1% ou 2% de DL-metionina não diferiu (P>0,05) do observado nos tanques sem restrição alimentar. Concluiu-se que é possível restringir as taxas de arraçoamento de juvenis de tilápia do Nilo, mantidos em tanques BFT de cultivo, em 25%, sem prejuízo zootécnico, desde que se faça a suplementação da dieta com, pelo menos, 1% de DL-metionina. Palavras-chave: Bioflocos. Aminoácido. Aquicultura. Qualidade de água.