RESUMO O presente estudo teve como objetivo avaliar a influência do óleo essencial de alho (OEA) sobre o desempenho produtivo e as variáveis morfométricas de pós-larvas de acará severo (Heros severus). Foi realizado ensaio de crescimento com 150 pós-larvas severas (1,6 ± 0,03 mg e 5,58 ± 0,1 mm), distribuídas em quinze aquários de 1 L, com aeração constante. Os peixes foram distribuídos em delineamento inteiramente casualizado com cinco tratamentos, dietas contendo diferentes níveis de OEA (0,00; 0,05; 0,50; 1,00 e 1,50 g kg-1) e três repetições. As dietas foram oferecidas quatro vezes ao dia, até saciedade aparente, por 30 dias. Ao final do experimento, os peixes foram contados, pesados e medidos, para avaliação do desempenho produtivo e das variáveis morfométricas. O aumento dos níveis de OEA na dieta resultou em redução linear nos parâmetros de desempenho produtivo, com exceção da taxa de sobrevivência e uniformidade de peso e comprimento do lote, que não apresentaram diferenças significativas, assim como as variáveis morfométricas. Concentrações elevadas de OEA na dieta podem ser prejudiciais para larvas e pós-larvas de peixes, que podem ser mais sensíveis ao dano potencial que altas concentrações deste óleo essencial podem causar. Portanto, a inclusão de OEA em níveis acima de 0,05 g kg-1 em dietas para pós-larvas de acará severo não é recomendada.

ABSTRACT The present study aimed to evaluate the influence of garlic essential oil (GEO) on the growth performance and morphometric variables of severum (Heros severus) post-larvae. A growth trial was performed using 150 severum post-larvae (1.6 ± 0.03 mg and 5.58 ± 0.1 mm), distributed in fifteen 1-L aquaria, with constant aeration. The fish were essayed in a completely randomized design with five treatments, using diets containing graded levels of GEO (0.00, 0.05, 0.50, 1.00 and 1.50 g kg-1) and three replicates. The diets were offered four times a day, until apparent satiation, for 30 days. At the end of the experiment, the fish were counted, weighed and measured, to evaluate growth performance and morphometric variables. Increased diet levels of GEO resulted in a linear reduction in growth performance parameters, except for the survival rate, weight and length uniformity of the batch, and morphometric variables which did not present significant differences. Elevated concentrations of dietary GEO may be detrimental to larvae and post-larvae of fish, which could be more sensitive to the potential damage that high concentrations of this essential oil may cause. Therefore, the inclusion of GEO in levels above 0.05 g kg-1 in diets for severum post-larvae is not recommended.

ABSTRACT The influence of feeding frequency on growth performance, batch uniformity, and survival rate of severum (Heros severus) larvae and juveniles was investigated in two experiments. In the first, 200 five-day-old severum larvae with 3.20±0.31 mg and 6.20±0.39 mm were randomly distributed into 20 aquaria (1 L) and fed 500 Artemia nauplii larvae−1 day−1 for 15 days. In the second, 120 severum juveniles, 178.19±33.59 mg and 1.82±0.09 cm, were randomly distributed into 15 aquaria (300 L) and hand-fed a commercial diet (400.0 g kg−1 crude protein and 21.2 kJ g−1 gross energy) until apparent satiety for 30 days. For both experiments, feeding frequencies of one, two, three, four, and five meals day−1 were evaluated. We used four replicates for the first experiment and three for the second. At the end of both experiments, survival rate and batch uniformity were unaffected by the feeding frequency. Severum larvae fed three, four, and five meals day−1 showed higher final weight, weight gain, and specific growth rate, but only the larvae fed five meals day−1 showed higher final length and length gain than those fed once and twice day−1. Severum juveniles fed two, four, and five meals day−1 showed higher final weight, weight gain, and specific growth rate. Growth performance parameters of final length and length gain were not affected by feeding frequencies. Thus, we recommend that the optimal feeding frequency for severum larvae fed Artemia nauplii is three meals day−1 and for juvenile severum fed a commercial diet, the optimal frequency is two meals day−1.

Resumo: O objetivo deste trabalho foi avaliar o desempenho, a composição corporal e o estado fisiológico de alevinos de tambaqui (Colossoma macropomum), alimentados com dietas com diferentes teores de extrato de chá-verde (Camellia sinensis, ECV). Utilizou-se um delineamento inteiramente casualizado, com cinco tratamentos, diferentes níveis de ECV (0,00, 0,05, 0,30, 0,55 e 0,80 g kg-1) e três repetições. As dietas foram oferecidas aos alevinos duas vezes ao dia, por 90 dias. O aumento dos níveis de ECV na dieta promoveu um efeito quadrático positivo sobre lipídeo corporal, lipídeo hepático, retenção de lipídeo corporal, glicose e triglicerídeos totais, e os valores mínimos destas variáveis foram estimados com níveis de 0,61, 0,54, 0,73, 0,60 e 0,30 g kg-1 ECV na dieta, respectivamente. Houve efeito quadrático negativo sobre proteína corporal e hemoglobina, com o aumento dos níveis de ECV na dieta, e os valores máximos destas variáveis foram estimados com níveis de 0,59 e 0,46 g kg-1 ECV na dieta, respectivamente. Houve redução linear dos níveis de colesterol total, com o aumento dos níveis de inclusão do ECV na dieta. A inclusão de ECV na dieta, apesar de não influenciar o desempenho, reduz a gordura corporal e a do fígado; diminui o colesterol total, os triglicerídeos e a glicose; e promove o aumento da proteína corporal de alevinos de tambaqui, o que melhora a condição de saúde deste peixe, durante o cultivo, e a qualidade do produto final.

Abstract: The objective of this work was to evaluate the performance, body composition, and physiological state of tambaqui (Colossoma macropomum) fingerlings fed diets containing different levels of green tea (Camellia sinensis) extract (GTE). A completely randomized design was used with five treatments, different levels of GTE (0.00, 0.05, 0.30, 0.55, and 0.80 g kg-1) and three replicates. The diets were offered to fingerlings twice a day, for 90 days. The increase of dietary GTE levels promoted a positive quadratic effect on body lipids, hepatic lipids, retention of body lipids, glucose, and total triglycerides, and the minimum values of these variables were estimated with 0.61, 0.54, 0.73, 0.60, and 0.30g kg-1 GTE in the diet, respectively. There was a negative quadratic effect of the extract on body protein and hemoglobin with the increased GTE dietary level, and the maximum values of these variables were estimated with 0.59 and 0.46 g kg-1 GTE dietary level, respectively. Total cholesterol levels showed a linear reduction with increased GTE dietary level. The inclusion of GTE in the diet, although not affecting performance, decreases body and hepatic fat; reduces the levels of total cholesterol, triglycerides, and glucose; and promotes the increase of body protein of tambaqui fingerlings, improving fish health conditions, during cultivation, and the quality of the final product.

ABSTRACT The objective of this work was to evaluate the influence of photoperiod on growth, uniformity, and survival of larvae of the Amazonian ornamental fish severum (Heros severus). A completely randomized study was used with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replicates, with the aquaria as the experimental unit. Two hundred severum larvae (3.20±0.16 mg and 5.60±0.00 mm) were distributed into 20 aquariums of one litre at a density of 10 larvae per litre. For a period of 15 days, feed was supplied four times daily with Artemia nauplii in a proportion of 160 nauplii/larvae/feeding. At the end of the experimental period, growth, uniformity, and survival data were subjected to analyses of variance and significance. Manipulation of the photoperiod showed no change in variables because there was no difference in the growth, uniformity, or survival of severum larvae. Thus, for larvae of this species of up to 20 days of age, the manipulation of the photoperiod is not advantageous due to the possible increase in production costs. Therefore, it is recommended to use the photoperiod close to the natural environment.

Com este estudo objetivou-se avaliar o efeito do fotoperíodo sobre a composição centesimal de filés de juvenis de tilápia do Nilo. Utilizou-se um delineamento inteiramente casualizado com cinco tratamentos (0L:24E; 6L:18E; 12L:12E; 18L:6E; 24L:0E) e quatro repetições. Foram utilizados 160 alevinos de tilápia, distribuídos em 20 aquários (20L) em sistema de recirculação, temperatura controlada em 27 ºC e densidade de oito peixes por aquário. Os peixes foram alimentados duas vezes ao dia, com ração comercial extrusada contendo 40% de proteína bruta. Ao final de 75 dias, amostras do filé foram coletadas e armazenadas em freezer (-80 ºC) para posteriores análises da composição bromatológica. Não houve efeito dos diferentes fotoperíodos sobre a umidade e cinzas do filé (P>0,05). Por outro lado, os peixes sob fotoperíodo de 18L:6E apresentaram maior quantidade de proteína e retenção desta no filé, assim como menor quantidade de gordura e retenção de lipídeo (P<0,05). Portanto, pode-se concluir que o fotoperíodo pode alterar a composição corporal de alevinos de tilápia do Nilo, sendo que e o fotoperíodo de 18L:6E contribui para o aumento da concentração de proteína bruta e uma menor deposição de gordura no filé.

This study aimed to evaluate the effect of the photoperiod on the fillet composition of Nile tilapia juveniles. We employed a completely randomized design with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replications. We used 160 Nile tilapia juveniles, distributed in 20 tanks containing 20 liters of water, in a recirculation systems, at controlled temperature of 27 ºC and density of eight fish per tank. Fish were fed twice a day with commercial extruded feed containing 40% crude protein. Samples of the fillet at the end of 75 days were collected and stored in a freezer at -80 ºC for subsequent analysis of chemical composition. There was no effect of photoperiod on moisture and ash content of the fillet (P>0.05). The period 18L:6D showed higher amounts of protein in the fillet, as well as lower amounts of fat (P<0.05). Therefore, it can be concluded that the photoperiod can alter Nile tilapia body composition, and the photoperiod 18L:6D contributed to the higher concentration of crude protein and lower fat deposition in Nile tilapia fillets.