Efeitos da suplementação dietética de zinco e selênio quelatado para juvenis de Tilápia do Nilo (Oreochromis niloticus)

Abstract

Zinc (Zn) and selenium (SE) are essential micronutrients that influence fish development and physiology. This study aimed to evaluate the effects on growth and health in the Nile tilapia supplemented tilapia with gradual levels of amino acids (Zn-AA) and subjected to transport stress and gauge supplementation with zinc-l-selenomethionine (ZnSeMet) and subjected to low and high storage density (LSD and HSD respectively). In experiment 1, Nile tilapia (22g) individuals were fed 0, 25, 50, 75, or 100 mg Zn-AA kg-1 for 60 days. At the end of the experimental period, the fish were subjected to transport by 3 h. Linear regression showed better values of fish performance parameters fed 100 mg Zn-AA kg diet-1. Better values were observed in hematological and immunological levels, as well as in the plasma parameters of fish with increasing Zn-AA in the diet. The highest values of plasma glucose and alanine aminotransferase were found in the control group. In experiment 2 four extruded diets were formulated, where gradual levels of ZnSeMet were added to the basal diet by 0.0; 0.5; 1.0, and 2.0 mg kg-1 for fish (58g) grown in a water recirculation system (RAS) in LSD (15 fish tank-1 or 4.35 kg m-3) and HSD (45 fish tank-1 or 13.05 kg m-3) for 65 days. The best results for growth performance occurred in LSD and 1.0 or 2.0 mg ZnSeMet kg diet-1 treatments. The final biomass was higher in HSD treatments. In the interaction between LSD and 1.0 mg ZnSeMet kg diet- 1, there was an increase in total protein and cholesterol levels and reduced aspartate activity aminotransferase in plasma. The highest values of plasma and hematological and immunological parameters were observed in LSD fish. It is concluded that 100 mg Zn- AA kg diet-1 is recommended for Nile tilapia as it can improve its growth, metabolism, physiology, and immunity. LSD cultivation is also recommended with an added 1.0 mg ZnSeMet kg-1 diet, as it improves fish growth performance without affecting its health.