RESUMO

Tambaqui (Colossoma macropomum) is a species of great cultural and economic importance in aquaculture in the Amazon region. Methionine is considered the first limiting sulfur amino acid in practical fish diets, which encourages investigating its use in diets for tambaqui. This study aimed to verify the digestible methionine plus cystine (Met + Cys) requirement in diets for tambaqui (89.52 ± 0.53 g) for 60 days. The treatments investigated were: 6.50, 7.80, 9.10, 10.40, 11.70, and 13.00 g Met + Cys kg diet-1. The estimated requirement based on final weight, weight gain, feed conversion ratio, and specific growth rate was 9.04, 8.92, 8.91, and 8.58 g Met + Cys kg diet-1, respectively, while on body protein deposition, body fat deposition, body ash deposition, and nitrogen retention efficiency was 9.29, 9.20, 9.19, and 8.72 g Met + Cys kg diet-1, respectively. Linear regression demonstrated that increased digestible Met + Cys in the diet decreased plasma total protein, globulin, and liver total protein levels. Quadratic regression showed that the highest value for liver glycogen was found with a 10.40 g Met + Cys kg diet-1. Another quadratic regression demonstrated a lower hepatic aspartate aminotransferase (AST) enzymatic activity in fish fed between 7.80 and 11.70 g Met + Cys kg diet-1. The different treatments did not influence the erythrogram. In conclusion, when considering an integrative view of the results for growth performance, whole-body deposition, and liver parameters without harming the physiological and metabolic status, we recommended choosing a diet with digestible Met + Cys between 8.58 and 9.29 g kg- 1 for tambaqui.

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RESUMO

This study investigated the possible antinutritional effects of Parkia platycephala lectin (0, 20, 40, or 60 mg kg-1 of diet) on tambatinga feeding for 60 days as well as methods of inactivating this protein. Weight gain, specific growth rate, and relative weight gain decreased, and the feed conversion rate increased with the increase in dietary lectin. The hepatic glycogen levels of fish fed 60 mg kg-1 were higher than those of fish fed 20 and 40 mg kg-1. Diets containing 40 and 60 mg kg-1 increased muscle glucose levels compared to the control group. Fish-fed diets containing lectin showed reduced muscle glycogen compared to those receiving the control diet. Fish fed 60 mg kg-1 presented lower muscle protein levels than those fed 20 mg kg-1. In vitro tests showed that the hemagglutination activity of lectin was inhibited by d-mannose, d-glucose, and α-methyl-d-mannopyranoside. Thermal treatment at 50­60°C was sufficient to reduce the action of lectin, as well as a pH below and above the 6­7 range. Therefore, the use of P. platycephala meals as a dietary ingredient for tambatinga with no lectin inac-tivation is not recommended as it can negatively affect the fish's biochemical parameters and growth. Acid or alkaline solutions can be an alternative for inactivating the protein and improving its use by fish and other animals.(AU)

Este estudo investigou possíveis efeitos antinutricionais da lectina de Parkia platycephala (0, 20, 40 ou 60 mg kg-1 de dieta) na alimentação de tambatinga por 60 dias, bem como métodos de inativação dessa proteína. O ganho de peso, a taxa de crescimento específico e o ganho de peso relativo diminu-íram, enquanto o índice de conversão alimentar aumentou com o incremento de lectina na dieta. Os níveis de glicogênio hepático dos peixes alimentados com 60 mg kg-1 foram superiores aos dos que ingeriram 20 e 40 mg kg-1. Dietas contendo 40 e 60 mg kg-1 aumentaram os níveis de glicose muscular em comparação com os que receberam a dieta controle. Nos animais cuja dieta continha lectina, redu-ziu-se o glicogênio muscular em comparação com os da dieta controle. Os espécimes alimentados com 60 mg kg-1 apresentaram menor nível de proteína muscular do que aqueles que consumiram 20 mg kg-1. Testes in vitro mostraram que a atividade de hemaglutinação da lectina foi inibida por D-mano-se, D-glicose e α-metil-D-manopiranosídeo. O tratamento térmico entre 50 e 60°C foi suficiente para reduzir a ação da lectina, assim como o pH abaixo de 6 e acima de 7. Portanto, usar farelo de P. pla-tycephala como ingrediente em dieta para tambatinga sem inativação da lectina não é recomendado, pois pode afetar negativamente os parâmetros bioquímicos e o crescimento dos exemplares. Soluções ácidas ou alcalinas podem ser uma alternativa para inativar a proteína e melhorar sua utilização em peixes e outros animais.(AU)

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RESUMO

Lippia grata (formerly known as Lippia gracillis) is an aromatic plant native to Brazil, with leaves rich in essential oils that possess significant biological activities. We evaluated the effect of essential oil of L. grata (EOLG) as a dietary additive on the growth, somatic indices, and biochemical parameters of juveniles (5.25 ± 0.26 g) of tambatinga, a hybrid fish obtained by crossing tambaqui (Colossoma macropomum) with pirapitinga (Piaractus brachypomum) of great economic importance in north and northeastern Brazil. We evaluated four dietary treatments, consisting of EOLG supplemented at 0.0, 0.5, 1.0, and 2.0 mL kg-1, over 60 days. Carcass yield was significantly higher in fish fed all EOLG diets compared to those fed the control diet (0.0 mL kg-1). Animals that received the 0.5 mL kg-1 treatment gained significantly more weight and showed a higher specific growth rate than those treated with 1.0 and 2.0 ml kg-1 EOLG, although none differed significantly from the control. The feed conversion rate was significantly lower in the 0.5 than in the 1.0 mL kg-1 treatment. Compared with higher concentrations, the diet containing 0.5 mL kg-1 EOLG increased the use of muscle glycogen, glucose, and lactate to meet energy demands, avoiding the use of muscle protein. Our results suggest that dietary supplementation with EOLG significantly improves carcass yield in tambatinga juveniles but that concentrations above 0.5 mL kg-1 may compromise growth rates and carbohydrate metabolism in this fish.(AU)

Lippia grata (previamente conhecida como Lippia gracillis) é uma planta aromática nativa do Brasil, com folhas ricas em óleos essenciais que possuem atividades biológicas significativas. Avaliamos o efeito do óleo essencial de L. grata (OELG) como aditivo alimentar sobre o crescimento, índices somáticos e parâmetros bioquímicos de juvenis (5,25 ± 0,26 g) de tambatinga, um hibrido obtido do cruzamento de tambaqui (Colossoma macropomum) com pirapitinga (Piaractus brachypomum) com grande importância econômica no norte e nordeste do Brazil. Foram avaliados quatro tratamentos dietéticos consistindo na suplementação com OELG em 0,0; 0,5; 1,0 e 2,0 mL kg-1 durante 60 dias. O rendimento de carcaça foi significativamente maior nos peixes alimentados com todas as dietas contendo OELG em comparação à dieta controle. Os animais do tratamento 0,5 mL kg-1 ganharam significativamente mais peso e apresentaram maior taxa de crescimento específico do que aqueles tratados com 1,0 e 2,0 mL kg-1 OELG, embora nenhum tenha diferido significativamente do controle. A taxa de conversão alimentar foi significativamente menor no tratamento 0,5 mL kg-1 do que no tratamento 1,0 mL kg-1. Comparada com as concentrações mais altas, a dieta contendo 0,5 mL kg-1 OELG aumentou o uso de glicogênio muscular, glicose e lactato para suprir as demandas energéticas, evitando o uso de proteína muscular. Nossos resultados sugerem que a suplementação dietética com OELG melhora significativamente o rendimento de carcaça de juvenis de tambatinga, mas concentrações acima de 0,5 mL kg-1 podem comprometer as taxas de crescimento e metabolismo de carboidratos desses peixes.(AU)

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