Hidróxi-selenometionina na dieta e seu efeito no desempenho, imunidade e sistema antioxidante do tambaqui (Colossoma macropomum)

• Autor(a) principal: Ferreira, Celma Maria
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFMT
• Texto Completo: http://ri.ufmt.br/handle/1/3354
• topic: Crescimento; Enzimas antioxidantes; Estresse; Piscicultura; Selênio orgânico; CNPQ::CIENCIAS AGRARIAS; Antioxidant enzymes; Fish farming; Growth; Organic selenium; Stress

The aim of this study was to evaluate the effect of selenium (Se), supplemented in the diet in the form of hydroxy-selenomethionine (OH-SeMet; Selisseo®, Adisseo), on the performance, innate biochemical and immunological parameters, antioxidant system and muscle deposition of tambaqui (Colossoma macropomum) exposed to transport stress. A total of 195 fish weighing 15.71 ± 1.90 g (mean ± standard deviation) were stored in fifteen 150-L experimental tanks (13 fish/tank) and fed for 75 days a feed formulated using a premix without selenium and incorporated with OH-SeMet at different concentrations (0, 0.3, 0.6, 0.9 and 1.2 mg Se/kg) (5 treatments × 3 replicates). Samples were collected at the beginning of the experiment (n = 15 fish) and at 75 days of feeding with the experimental diets (n = 45 fish). Then, the fish were challenged with road transportation for 4 h in plastic bags (60 L) containing water and inflated with oxygen, and sampling took place before the challenge (baseline), upon arrival (n = 45 fish) and 24 h (n = 45 fish) and 1 week (n = 45 fish) later. Production performance was evaluated at the end of the 75 days of feeding with the experimental diets. At each sampling time, blood was collected to evaluate physiological responses and innate immunity parameters. Next, the fish were slaughtered to remove the liver, for an analysis of the biochemical parameters of oxidative stress; and muscle (fillet), to measure the selenium concentration in the meat. Supplementation with OH-SeMet for 75 days pre-stress did not affect the production performance of the tambaqui or change their hematological parameters (red and white cells) or immunity (total proteins and globulin). Rather, it promoted an increase in leukocyte respiratory burst activity from the Se inclusion level of 0.6 mg/kg and affected the antioxidant status of the fish, leading to an increase in glutathione peroxidase (GPx) activity and a decrease in the concentration of reduced glutathione (GSH). Selenium inclusion at 0.9 mg/kg induced an increase in glutathione-S-transferase (GST) activity. The Se concentration in the fillet increased significantly as the OH-SeMet concentrations in the diet were increased. As a stressor agent, transport induced an increase in blood cortisol and glucose; hemoconcentration, as represented by an increase in hematocrit, erythrocyte number, hemoglobin and mean corpuscular hemoglobin concentration (MCHC); and osmotic imbalance. This resulted in hypochloremia, higher plasma protein concentration and increased red blood cell volume, and these changes were not minimized by dietary inclusion of Se. The activation of the antioxidant defense parameters after stress led to the regulation of reactive oxygen species (ROS), as evidenced by the decrease in leukocyte respiratory burst activity after management. These results indicate that tambaqui juveniles can use muscle-stored selenium when challenged with transport and that hydroxy-selenomethionine supplementation in commercial diets can ensure tissue selenium reserves as a contingency in case of stress. Dietary supplementation with Se at the concentration of 0.9 mg/kg improved innate immunity parameters and provided greater antioxidant-system enzyme activity in juvenile tambaqui (C. macropomum) after this acute stressor was applied.