Oxidative stress, biotransformation enzymes and histopathological alterations in Nile tilapia (Oreochromis niloticus) exposed to new and used automotive lubricant oil.

Lubricant oils are among oil-based products that are not fully consumed during its use, thereby producing non-biodegradable residues which can cause contamination of natural systems. This study evaluated the toxicity of new and used lubricating oil (0.01 and 0.1 mL L-1) in adult Nile tilapia (Oreochromis niloticus), by assessing the effects on oxidative stress, biotransformation enzymes (liver and gills), and histopathological alterations on hepatic and pancreatic tissues after 3 and 7 days of exposure. Results showed that 3-days exposure to 0.1 mL L-1 of used and new lubricating oil increased the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) levels in liver of O. niloticus, respectively. In gills, catalase (CAT) was decreased in fish exposed to 0.1 mL L-1 of non-used oil after 3 days, but pronounced increases in CAT was detected after 7 days-exposure to both new and used oil. Shorter exposure to both concentrations of new and used oil also raised glutathione-S-transferase activity (GST) in gills. Ethoxyresorufin-O-deethylase (EROD) was induced in liver of fish exposed to 0.1 mL L-1of used oil after 3 and 7 days, however a reduced response of this enzyme was detected in gills of animals from both oil treatments. In vitro analysis showed that hepatic EROD was inhibited by lubricating oil exposures, with more pronounced responses in treatments containing used oil. Hepatic lesions, such as cytoplasmic vacuolization, nuclei abnormally, changes in hepatocytes shape, steatosis, cholestasis, eosinophilic inclusions and necrosis were mainly increased by 7 days exposure to used lubricating oil at higher concentration.

Use of 17beta-estradiol for Leporinus microcephalus feminization / Utilização de 17beta-estradiol para feminização de Leporinus macrocephalus

The aim of the study was to establish an effective feminization protocol for Leporinus macrocephalus using the 17-estradiol (E2). Thus, one hundred and fifty fingerlings with 50 days old post-hatch were randomly distributed in fifteen experimental tanks of 90L and fed for 60 days on a diet supplemented with 50 or 100mg Kg-1 of E2. At the end of the experiment, sex ratios were determined through histological and macroscopic observations. Histologically, the differentiated ovaries were evidenced by the presence of numerous nests of oogonia and oocytes in primary growth stage. The female ratio (73%) for the group treated with 100mg Kg-1 E2 was significantly higher than those of control (52%) and 50mg Kg-1 treatment (48%) groups. These results indicate that 100 mg Kg-1 E2 administered for 60 days was the most effective treatment for 50 days old L. macrocephalus post larval feminization. In conclusion, the successful sex control can be achieved through dietary hormonal manipulation. However, future studies should be conducted to evaluate the economic feasibility of this technique.(AU)

O objetivo do estudo foi avaliar o efeito do 17-estradiol (E2) na feminização de Leporinus macrocephalus. Dessa forma, 150 alevinos com 50 dias de idade foram distribuídos aleatoriamente em 15 tanques experimentais de 90 L e alimentados por 60 dias com dieta suplementada com 50 ou 100 mg kg-1 de E2. No final do experimento, as proporções sexuais foram determinadas por meio de observações histológicas e macroscópicas. Histologicamente, os ovários diferenciados foram evidenciados pela presença de numerosos ninhos de oogonia e oócitos em fase crescimento primário. O percentual de fêmeas (77%) do grupo tratado com 100 mg kg-1 E2 foi significativamente maior comparado ao grupo controle (52%) e ao grupo 50 mg kg-1 (48%). Os resultados obtidos neste estudo inicial indicaram que 100 mg kg-1 de E2, administrados durante 60 dias, foi o tratamento mais efetivo na feminização de L. macrocephalus com 50 dias de idade. No entanto, estudos futuros com variações no intervalo de aplicações podem trazer ainda melhores resultados.(AU)

Use of 17beta-estradiol for Leporinus microcephalus feminization / Utilização de 17beta-estradiol para feminização de Leporinus macrocephalus

The aim of the study was to establish an effective feminization protocol for Leporinus macrocephalus using the 17-estradiol (E2). Thus, one hundred and fifty fingerlings with 50 days old post-hatch were randomly distributed in fifteen experimental tanks of 90L and fed for 60 days on a diet supplemented with 50 or 100mg Kg-1 of E2. At the end of the experiment, sex ratios were determined through histological and macroscopic observations. Histologically, the differentiated ovaries were evidenced by the presence of numerous nests of oogonia and oocytes in primary growth stage. The female ratio (73%) for the group treated with 100mg Kg-1 E2 was significantly higher than those of control (52%) and 50mg Kg-1 treatment (48%) groups. These results indicate that 100 mg Kg-1 E2 administered for 60 days was the most effective treatment for 50 days old L. macrocephalus post larval feminization. In conclusion, the successful sex control can be achieved through dietary hormonal manipulation. However, future studies should be conducted to evaluate the economic feasibility of this technique.

O objetivo do estudo foi avaliar o efeito do 17-estradiol (E2) na feminização de Leporinus macrocephalus. Dessa forma, 150 alevinos com 50 dias de idade foram distribuídos aleatoriamente em 15 tanques experimentais de 90 L e alimentados por 60 dias com dieta suplementada com 50 ou 100 mg kg-1 de E2. No final do experimento, as proporções sexuais foram determinadas por meio de observações histológicas e macroscópicas. Histologicamente, os ovários diferenciados foram evidenciados pela presença de numerosos ninhos de oogonia e oócitos em fase crescimento primário. O percentual de fêmeas (77%) do grupo tratado com 100 mg kg-1 E2 foi significativamente maior comparado ao grupo controle (52%) e ao grupo 50 mg kg-1 (48%). Os resultados obtidos neste estudo inicial indicaram que 100 mg kg-1 de E2, administrados durante 60 dias, foi o tratamento mais efetivo na feminização de L. macrocephalus com 50 dias de idade. No entanto, estudos futuros com variações no intervalo de aplicações podem trazer ainda melhores resultados.

Effects of methylphenidate on the aggressive behavior, serotonin and dopamine levels, and dopamine-related gene transcription in brain of male Nile tilapia (Oreochromis niloticus).

The occurrence of pharmaceuticals in the aquatic environment has increased considerably in the last decades, causing negative biochemical, physiological, and behavioral effects in aquatic organisms. In this study, we evaluated the effects of methylphenidate (MPH) on the aggressive behavior, dopamine-related gene transcript levels, monoamine levels, and carboxylesterase transcript levels and activity in the brain of male Nile tilapia (Oreochromis niloticus). Carboxylesterase activity was also measured in the liver and gills. Fish were exposed for 5 days to MPH at 20 and 100 ng L-1. Fish exposed to 100 ng L-1 of MPH showed increased aggressiveness and decreased dopamine (DA) and serotonin (5-HT) levels. No changes were observed in plasma testosterone levels and in the transcript levels of D1 and D2 dopamine receptors, dopamine transporter (DAT), and carboxylesterase 2 (CES2). Exposure to 100 ng L-1 of MPH caused a decrease in the transcript levels of carboxylesterase 3 (CES3) and an increase in tyrosine hydroxylase (TH), while exposure to 20 ng L-1 of MPH increased the transcript levels of D5 dopamine receptor. Carboxylesterase activity was unchanged in the brain and liver and increased in the gills of fish exposed to 20 ng L-1. These results indicate that MPH at 100 ng L-1 increases aggressiveness in Nile tilapia, possibly due to a decrease in 5-HT levels in the brain and alterations in dopamine levels and dopamine-related genes.

Leporinus elongatus induced spawning using carp pituitary extract or mammalian GnRH analogue combined with dopamine receptor antagonists

Several studies have been developed to support the replacement of the crude carp pituitary extract (CPE) by synthetic products for induced reproduction of South American rheophilic species. However, results have been quite heterogeneous and there is no consensus or a routine use of synthetic products in these species. Thus, the aim of this study was to evaluate the ovulatory process in L. elongatus using different protocols of hormonal induction. Thus, fifteen wild mature females maintained at the Experimental Fish Station, Salto Grande, SP, Brazil were submitted to three different hormonal treatments: CPE (fractioned dose: 0.5 and 5.0 mg kg-1 ); mGnRHa (single dose: 3.5 µg kg-1 ) and mGnRHa (single dose: 5.0 µg kg-1 ). The spawning rate and absolute fecundity were similar among the treatments, but fertility rates were higher for CPE treatment (23.60 ± 9.40) then for mGnRHa treatments (close to or zero zero). Although females ovulated in all treatments, none of them provided viable embryos, showing hatching rates close to zero or zero. Both mGnRHa treatments were more potent for inducing the ovulatory process then CPE treatment, which was evidenced by the fact that the formers showed higher volume density of postovulatory follicles (POF). Accordingly, E2 and 17α-OHP plasma levels were higher for the mGnRHa treated females compared to the CPE one at the time of ovulation. In this study we confirmed previous scientific evidence that, regardless of whether promoting ovulation, the use of conventional CPE and GnRH doses are not appropriate for some South American migratory species, due to the nonattainment of viable embryos. Moreover, we have brought new information about the relationship between reproductive performance and gonadal steroids concentrations using different hormonal therapies, contributing to understand the reasons for Leporinus elongatus embryo loss in induced spawning.(AU)

Leporinus elongatus induced spawning using carp pituitary extract or mammalian GnRH analogue combined with dopamine receptor antagonists

Several studies have been developed to support the replacement of the crude carp pituitary extract (CPE) by synthetic products for induced reproduction of South American rheophilic species. However, results have been quite heterogeneous and there is no consensus or a routine use of synthetic products in these species. Thus, the aim of this study was to evaluate the ovulatory process in L. elongatus using different protocols of hormonal induction. Thus, fifteen wild mature females maintained at the Experimental Fish Station, Salto Grande, SP, Brazil were submitted to three different hormonal treatments: CPE (fractioned dose: 0.5 and 5.0 mg kg-1 ); mGnRHa (single dose: 3.5 µg kg-1 ) and mGnRHa (single dose: 5.0 µg kg-1 ). The spawning rate and absolute fecundity were similar among the treatments, but fertility rates were higher for CPE treatment (23.60 ± 9.40) then for mGnRHa treatments (close to or zero zero). Although females ovulated in all treatments, none of them provided viable embryos, showing hatching rates close to zero or zero. Both mGnRHa treatments were more potent for inducing the ovulatory process then CPE treatment, which was evidenced by the fact that the formers showed higher volume density of postovulatory follicles (POF). Accordingly, E2 and 17α-OHP plasma levels were higher for the mGnRHa treated females compared to the CPE one at the time of ovulation. In this study we confirmed previous scientific evidence that, regardless of whether promoting ovulation, the use of conventional CPE and GnRH doses are not appropriate for some South American migratory species, due to the nonattainment of viable embryos. Moreover, we have brought new information about the relationship between reproductive performance and gonadal steroids concentrations using different hormonal therapies, contributing to understand the reasons for Leporinus elongatus embryo loss in induced spawning.

Leporinus elongatus induced spawning using carp pituitary extract or mammalian GnRH analogue combined with dopamine receptor antagonists.

Several studies have been developed to support the replacement of the crude carp pituitary extract (CPE) by synthetic products for induced reproduction of South American rheophilic species. However, results have been quite heterogeneous and there is no consensus or a routine use of synthetic products in these species. Thus, the aim of this study was to evaluate the ovulatory process in L. elongatus using different protocols of hormonal induction. Thus, fifteen wild mature females maintained at the Experimental Fish Station, Salto Grande, SP, Brazil were submitted to three different hormonal treatments: CPE (fractioned dose: 0.5 and 5.0 mg kg-1); mGnRHa (single dose: 3.5 µg kg-1) and mGnRHa (single dose: 5.0 µg kg-1). The spawning rate and absolute fecundity were similar among the treatments, but fertility rates were higher for CPE treatment (23.60 ± 9.40) then for mGnRHa treatments (close to or zero zero). Although females ovulated in all treatments, none of them provided viable embryos, showing hatching rates close to zero or zero. Both mGnRHa treatments were more potent for inducing the ovulatory process then CPE treatment, which was evidenced by the fact that the formers showed higher volume density of postovulatory follicles (POF). Accordingly, E2 and 17α-OHP plasma levels were higher for the mGnRHa treated females compared to the CPE one at the time of ovulation. In this study we confirmed previous scientific evidence that, regardless of whether promoting ovulation, the use of conventional CPE and GnRH doses are not appropriate for some South American migratory species, due to the non-attainment of viable embryos. Moreover, we have brought new information about the relationship between reproductive performance and gonadal steroids concentrations using different hormonal therapies, contributing to understand the reasons for Leporinus elongatus embryo loss in induced spawning.

Estrogenic and anti-androgenic effects of the herbicide tebuthiuron in male Nile tilapia (Oreochromis niloticus).

Tebuthiuron is a phenylurea herbicide widely used in agriculture that can reach the aquatic environments, possibly posing negative effects to the aquatic biota. Phenylurea herbicides, such as diuron, are known to cause estrogenic and anti-androgenic effects in fish, but no such effects were yet reported for tebuthiuron exposure. Thus, the aim of this study was to evaluate if tebuthiuron, at environmentally relevant concentrations (100 and 200ng/L) and after 25days of exposure have estrogenic and/or anti-androgenic effects on male of Nile tilapia (Oreochromis niloticus), through the evaluation of plasmatic testosterone (T) and estradiol (E2) levels, brain aromatase (CYP19) levels (western-blot), and by evaluating the histology of the testicles. When compared to the control group, plasmatic T levels decreased about 76% in the animals exposed to 200ng/L of tebuthiuron, while E2 levels increased about 94%, which could be related to a significant increase (77%) in CYP19A1 levels, an enzyme that catalyzes the conversion of androgens into estrogens. Histological analyses of the testicles also demonstrated that tebuthiuron at both tested concentrations caused a decrease in the diameter of the seminiferous tubules and in the diameter of the lumen. Therefore, the gonadosomatic index (GSI) was reduced by 36% % in the animals exposed 200ng/L to tebuthiuron. Indeed, the relative frequency of spermatocytes and spermatids increased respectively 73% (200ng/L) and 61% (100ng/L) in the tebuthiuron exposed animals, possibly due to the impairment of sperm release into the lumen, that was decreased 93% (200ng/L) in the treated animals compared to the control. These results confirm that tebuthiuron causes estrogenic and anti-androgenic effects in Nile tilapias at environmentally relevant concentrations.

Diuron metabolites act as endocrine disruptors and alter aggressive behavior in Nile tilapia (Oreochromis niloticus).

Diuron and its biodegradation metabolites were recently reported to cause alterations in plasma steroid hormone concentrations with subsequent impacts on reproductive development in fish. Since steroid hormone biosynthesis is regulated through neurotransmission of the central nervous system (CNS), studies were conducted to determine whether neurotransmitters that control hormone biosynthesis could be affected after diuron and diuron metabolites treatment. As the same neurotransmitters and steroid hormones regulate behavioral outcomes, aggression was also evaluated in male Nile tilapia (Oreochromis niloticus). Male tilapias were exposed for 10 days to waterborne diuron and the metabolites 3,4-dichloroaniline (DCA), 3,4-dichlorophenyl-N-methylurea (DCPMU), at nominal concentrations of 100 ng L-1. In contrast to Diuron, DCA and DCPMU significantly diminished plasma testosterone concentrations (39.4% and 36.8%, respectively) and reduced dopamine levels in the brain (47.1% and 44.2%, respectively). In addition, concentrations of the stress steroid, cortisol were increased after DCA (71.0%) and DCPMU (57.8-%) exposure. A significant decrease in aggressive behavior was also observed in animals treated with the metabolites DCA (50.9%) and DCPMU (68.8%). These results indicate that biotransformation of diuron to active metabolites alter signaling pathways of the CNS which may impact androgen and the stress response as well as behavior necessary for social dominance, growth, and reproduction.

Estrogenic activities of diuron metabolites in female Nile tilapia (Oreochromis niloticus).

Some endocrine disrupting chemicals (EDCs) can alter the estrogenic activities of the organism by directly interacting with estrogen receptors (ER) or indirectly through the hypothalamus-pituitary-gonadal axis. Recent studies in male Nile tilapia (Oreochromis niloticus) indicated that diuron may have anti-androgenic activity augmented by biotransformation. In this study, the effects of diuron and three of its metabolites were evaluated in female tilapia. Sexually mature female fish were exposed for 25 days to diuron, as well as to its metabolites 3,4-dichloroaniline (DCA), 3,4-dichlorophenylurea (DCPU) and 3,4-dichlorophenyl-N-methylurea (DCPMU), at concentrations of 100 ng/L. Diuron metabolites caused increases in E2 plasma levels, gonadosomatic indices and in the percentage of final vitellogenic oocytes. Moreover, diuron and its metabolites caused a decrease in germinative cells. Significant differences in plasma concentrations of the estrogen precursor and gonadal regulator17α-hydroxyprogesterone (17α-OHP) were not observed. These results show that diuron metabolites had estrogenic effects potentially mediated through enhanced estradiol biosynthesis and accelerated the ovarian development of O. niloticus females.

Anti-androgenic activities of diuron and its metabolites in male Nile tilapia (Oreochromis niloticus).

Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is a widely used herbicide which has been frequently detected in surface waters throughout the world. In vivo bioassay guided fractionation studies indicated that diuron may have estrogenic activity augmented by biotransformation. This study evaluated the effects of diuron and three of its metabolites on plasma hormone concentrations and spermatogenesis of the freshwater fish Nile tilapia (Oreochromis niloticus). Sexually mature male fish were exposed for 25 days to diuron, as well to its metabolites 3,4-dichloroaniline (DCA), 3,4-dichlorophenylurea (DCPU) and 3,4-dichlorophenyl-N-methylurea (DCPMU), at concentrations of 200ng/L. Testosterone levels were decreased by diuron, but had limited effects on gonadal histology. Diuron metabolites, however, caused significant decreases in testosterone and in 11-ketotestosterone, gonadosomatic index, diameter of seminiferous tubules and in the mean percentages of germ cells (spermatids and spermatozoa). We conclude that these metabolites have antiandrogenic activity to male Nile tilapia, potentially causing reproductive impairment in male fish.

Replacement of fish meal by soybean meal in diets for juveniles of curimba / Substituição da farinha de peixe pelo farelo de soja em dietas para juvenis de curimba

Replacement of fish meal by soybean meal in juvenile curimba (Prochilodus lineatus) diets was evaluated. Five isonitrogenous (26% crude protein) and isocaloric (4,000 kcal of gross energy kg-1) diets with 0, 25, 50, 75 and 100% of replacement were used. Fish (3.71 ± 0.54 g) were distributed in 25 tanks (120 liters). The diets were provided for 84 days. Total replacement of fish meal (100%) by soybean meal worsened weight gain, feed conversion and protein efficiency ratio. An increase in carcass fat was observed at the expense of reducing protein percentage, as well as an increase in hepatosomatic index. It was concluded that replacing 75.0% fish meal by soybean meal (33.2% of inclusion) did not affect the animal growth, although there been observed changes in corporal composition and hepatic hyperplasia.

Foi avaliada a substituição da farinha de peixe pelo farelo de soja em dietas para juvenis curimba (Prochilodus lineatus). Foram utilizadas cinco dietas isoproteicas (26% de proteína bruta) e isocalóricas (4.000 kcal de energia bruta kg-1) com 0, 25, 50, 75 e 100% de substituição. Os peixes (3,71 ± 0,54 g) foram distribuídos em 25 caixas plásticas de 120 litros. A alimentação foi fornecida durante 84 dias. A substituição total da farinha de peixe pelo farelo de soja piorou o ganho de peso, a conversão alimentar e a taxa de eficiência proteica. Nestes peixes também foi observado aumento do teor de gordura em detrimento da diminuição da porcentagem de proteína da carcaça e aumento no índice hepatossomático. Pode-se concluir que substituição de até 75,0% da farinha de peixe pelo farelo de soja (33,2% de inclusão) não afetou o crescimento dos animais, embora tenha provocado alterações na composição corporal e hiperplasia hepática.

Replacement of fish meal by soybean meal in diets for juveniles of curimba / Substituição da farinha de peixe pelo farelo de soja em dietas para juvenis de curimba

Replacement of fish meal by soybean meal in juvenile curimba (Prochilodus lineatus) diets was evaluated. Five isonitrogenous (26% crude protein) and isocaloric (4,000 kcal of gross energy kg-1) diets with 0, 25, 50, 75 and 100% of replacement were used. Fish (3.71 ± 0.54 g) were distributed in 25 tanks (120 liters). The diets were provided for 84 days. Total replacement of fish meal (100%) by soybean meal worsened weight gain, feed conversion and protein efficiency ratio. An increase in carcass fat was observed at the expense of reducing protein percentage, as well as an increase in hepatosomatic index. It was concluded that replacing 75.0% fish meal by soybean meal (33.2% of inclusion) did not affect the animal growth, although there been observed changes in corporal composition and hepatic hyperplasia.

Foi avaliada a substituição da farinha de peixe pelo farelo de soja em dietas para juvenis curimba (Prochilodus lineatus). Foram utilizadas cinco dietas isoproteicas (26% de proteína bruta) e isocalóricas (4.000 kcal de energia bruta kg-1) com 0, 25, 50, 75 e 100% de substituição. Os peixes (3,71 ± 0,54 g) foram distribuídos em 25 caixas plásticas de 120 litros. A alimentação foi fornecida durante 84 dias. A substituição total da farinha de peixe pelo farelo de soja piorou o ganho de peso, a conversão alimentar e a taxa de eficiência proteica. Nestes peixes também foi observado aumento do teor de gordura em detrimento da diminuição da porcentagem de proteína da carcaça e aumento no índice hepatossomático. Pode-se concluir que substituição de até 75,0% da farinha de peixe pelo farelo de soja (33,2% de inclusão) não afetou o crescimento dos animais, embora tenha provocado alterações na composição corporal e hiperplasia hepática.

Selênio orgânico na alimentação de matrizes de tilápia-do-Nilo (Oreochromis niloticus) / Organic selenium in the diet of Nile tilapia (Oreochromis niloticus) broodstock

O objetivo deste trabalho foi avaliar o efeito da suplementação de selênio orgânico na dieta de matrizes de tilápia-do-Nilo. Foi avaliado o desempenho zootécnico e reprodutivo das matrizes, assim como o crescimento das larvas (progênies). Utilizaram-se 80 peixes em idade reprodutiva, com peso médio de 121 g, divididos em grupos de quatro animais (três fêmeas e um macho), estocados em 20 tanques de 1,5 m3. Os peixes foram alimentados com cinco dietas contendo níveis crescentes de suplementação com selênio orgânico (0,0; 0,25; 0,50; 0,75 e 1,0 mg kg-1 de ração). O delineamento experimental utilizado foi inteiramente casualizado com cinco tratamentos e quatro repetições. Para avaliar o desempenho zootécnico da progênie, as larvas produzidas de cada tratamento foram divididas em quatro aquários e alimentadas durante 30 dias com ração comercial (45% PB). O desempenho zootécnico e reprodutivo das matrizes não apresentou diferenças estatísticas (p > 0,05). Por outro lado, as matrizes que foram alimentadas com dietas suplementadas com 0,50 mg de selênio orgânico produziram larvas que apresentaram melhor (p < 0,05) ganho de peso em relação as que receberam a dieta-controle.(AU)

The aim of this study to test the effect of organic selenium supplementation in the diets of Nile tilapia broodstock. Growth, reproductive performance and performance of fingerlings were evaluated. Eighty adult fish were used, with average weight of 121.7 g and divided into groups of four animals (3 female and 1 male) stocked in 20 tanks with 1.5 cubic meters. The fish were fed five diets containing different levels of organic selenium (0.0, 0.25, 0.50, 0.75, and 1.0 mg kg-1 ration). In the experimental period, females from all tanks were captured and the eggs collected. The experimental design was entirely randomized, with five treatments and four replicates. To evaluate progeny performance, the fingerlings were shared in four aquariums and fed during 30 days with commercial diet (45% CP). The supplementation with organic selenium did not affect the productive performance as with the reproductive parameters of the broodstock (p > 0.05). On the other hand, the broodstock fed with 0.50 mg of organic selenium produced fingerlings that presented improved weight gain (p < 0.05) compared to fish fed the control diet.(AU)

Selênio orgânico na alimentação de matrizes de tilápia-do-Nilo (Oreochromis niloticus) / Organic selenium in the diet of Nile tilapia (Oreochromis niloticus) broodstock

O objetivo deste trabalho foi avaliar o efeito da suplementação de selênio orgânico na dieta de matrizes de tilápia-do-Nilo. Foi avaliado o desempenho zootécnico e reprodutivo das matrizes, assim como o crescimento das larvas (progênies). Utilizaram-se 80 peixes em idade reprodutiva, com peso médio de 121 g, divididos em grupos de quatro animais (três fêmeas e um macho), estocados em 20 tanques de 1,5 m3. Os peixes foram alimentados com cinco dietas contendo níveis crescentes de suplementação com selênio orgânico (0,0; 0,25; 0,50; 0,75 e 1,0 mg kg-1 de ração). O delineamento experimental utilizado foi inteiramente casualizado com cinco tratamentos e quatro repetições. Para avaliar o desempenho zootécnico da progênie, as larvas produzidas de cada tratamento foram divididas em quatro aquários e alimentadas durante 30 dias com ração comercial (45% PB). O desempenho zootécnico e reprodutivo das matrizes não apresentou diferenças estatísticas (p > 0,05). Por outro lado, as matrizes que foram alimentadas com dietas suplementadas com 0,50 mg de selênio orgânico produziram larvas que apresentaram melhor (p < 0,05) ganho de peso em relação as que receberam a dieta-controle.

The aim of this study to test the effect of organic selenium supplementation in the diets of Nile tilapia broodstock. Growth, reproductive performance and performance of fingerlings were evaluated. Eighty adult fish were used, with average weight of 121.7 g and divided into groups of four animals (3 female and 1 male) stocked in 20 tanks with 1.5 cubic meters. The fish were fed five diets containing different levels of organic selenium (0.0, 0.25, 0.50, 0.75, and 1.0 mg kg-1 ration). In the experimental period, females from all tanks were captured and the eggs collected. The experimental design was entirely randomized, with five treatments and four replicates. To evaluate progeny performance, the fingerlings were shared in four aquariums and fed during 30 days with commercial diet (45% CP). The supplementation with organic selenium did not affect the productive performance as with the reproductive parameters of the broodstock (p > 0.05). On the other hand, the broodstock fed with 0.50 mg of organic selenium produced fingerlings that presented improved weight gain (p < 0.05) compared to fish fed the control diet.