One of the current challenges of global fish farming is developing plant‐based proteins as a feasible substitute for fishmeal in the formulation of aquafeeds. Substitution levels of fishmeal with hydrolyzed soybean meal (HSM) in diets for silver catfish (Rhamdia quelen) were evaluated for growth, protein metabolism and antioxidant activity. The experiment was carried out in a recirculation system of 20 tanks of 250 L. A total of 300 silver catfish juveniles were used to compose five treatments and four replicates per treatment. Levels of soybean hydrolysate (0%, 5%, 10%, 15% and 20%) were tested in diets (39% protein and 3,500 Kcal) for 60 days. Silver catfish growth was higher at all inclusion levels of HSM when compared to the control diet. No change was shown for body protein deposition. The production of nitrogenous compounds in the liver and muscle was also unaffected by any of the diets. The diet containing 20% HSM promoted an increase in the amounts of non‐protein thiols in the gills and brain. The HSM substitution levels of up to 20% of fishmeal in the diet increases growth and contributes to silver catfish antioxidant activity.
The reduction in the protein level and the supplementation of lysine (Lys) and methionine (Met) in the diet were evaluated in the performance and intestinal morphometry of silver catfish (Rhamdia quelen). The study was used in a completely randomized design for 63 days, where 320 fish (26.33 ± 0.40 g) were distributed in 20 tanks (250 L, 16 fish each) and fed until the apparent satiety was reached. Five diets were formulated, a positive control [38% of crude protein (CP) (38CP)], a negative control [34% of CP (34CP)] and three test diets [34% of CP supplemented with Lys (34L), 34% of CP supplemented with Met (34M) and 34% of CP supplemented with Lys plus Met (34LM)]. Final weight and condition factor were greater in fish fed the 34LM diet than in those fed the 34CP diet (p < .05). Body lipid deposition was lower in fish fed the 34CP diet than other diets (p = .0002). In the fillet, there was a lower deposition of lipids in fish fed with 34L diet than in fish fed with 34M and 34LM diets (p <.0001). Fish fed the 34LM diet had a higher AA content in the plasma than those fed 34L and 34CP diets (p < .0001). The lower villus height was observed in fish fed the 34L diet compared to the 38CP diet (p = .021). It is possible to reduce 4% of the CP level in silver catfish diets with supplementation of Lys and Met.
The increase in demand for fish production drives the search for food strategies to maximize productivity. In this review, the nutritional implications of the use of exogenous proteases on fish growth were described. Exogenous proteases help in digestive processes, acting in the hydrolysis of macromolecules and in the release of smaller particles, such as amino acids and peptides. Dietary supplementation improves fish growth, mainly due to the availability and greater use of nutrients. The action of proteases is directly linked to better intake, feed efficiency and protein synthesis. On the other hand, enzyme activity depends on substrate and dietary composition as there are limitations on digestibility. Furthermore, in feed processing, thermal stability and the form of inclusion of the protease influence its efficiency. However, the increase in fish weight gain can offset the cost of including the enzyme in the diet. However, there are still gaps regarding the effects of protease in fish feeding, for example, enzyme: specific substrate and enzyme: digestive system ratio; and, stabilization technologies (mainly extruded diets), so further studies are needed.
RESUMO O sistema de bioflocos é um meio de cultivo importante na piscicultura, pois conceitualmente utiliza pouca água. Neste trabalho foram testadas taxas de arraçoamento para jundiás e seus possíveis efeitos no crescimento, composição corporal e parâmetros hematológicos e bioquímicos de peixes cultivados em sistema de bioflocos. O experimento, com duração de 45 dias, utilizou 108 jundiás (24,75 ± 3,16 g), distribuídos em 9 tanques de 30 L (12 peixes por tanque). Foram testadas três taxas de alimentação (1, 2 ou 3% da biomassa dia-1) em triplicata. Para os parâmetros zootécnicos, houve aumento significativo na biomassa e no TCE. Os níveis de hemoglobina apresentaram ajuste quadrático. Os demais parâmetros hematológicos não apresentaram variação em função das taxas testadas. Não ocorreu efeito nos valores de proteína, lipídios, matéria seca e matéria mineral. Conclui-se que a taxa de arraçoamento diária de 3% resultou em maior produtividade e melhor estado de saúde dos jundiás cultivados em sistema de bioflocos.
Modo de acesso: World Wide Web Inclui bibliografia 1. Zootecnia 2. Bovinos.3. Suínos I. Título
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Neste estudo foi avaliada a eficiência do material de diferentes estruturas (alimentadores automáticos e caixa de armazenagem) na armazenagem das rações em viveiro de piscicultura. Os tipos de alimentadores testados foram: AFP (alimentador flutuante de polietileno) AFM (alimentador fixo de metal) e CAF (caixa d’água de fibra de vidro). Foram coletadas amostras de ração na abertura da embalagem (realizadas em diferentes pontos da embalagem), depois, após 1, 3, 5 e 7 dias, em cinco pontos dentro dos alimentadores. A avaliação da qualidade das rações foi realizada por meio de análises bromatológicas e TBARS. Durante o período de coleta das amostras, também foram aferidas temperatura e umidade do ar atmosférico e ambiente dentro das estruturas. Verificou-se que material estrutural do alimentador interfere na qualidade da ração, mas o período é a variável que mais influencia. No alimentador flutuante verificou-se maior umidade interna nos dias 3 e 7 (P<0,05). As rações sofreram alterações prejudiciais à sua qualidade no decorrer do tempo pela variação na composição bromatológica e atividade de TBARS. Nesse experimento o material de fibra apresentou maior eficiência na manutenção de qualidade de ração quando comparado aos demais, dessa forma sugere-se novas tecnologias ou outro tipo de estrutura para manter a qualidade da ração estocada. Apesar de a ração perder qualidade já no primeiro dia, não recomenda-se deixar mais que três dias a ração dentro da estrutura.
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