Desempenho produtivo, expressão de genes relacionados com o metabolismo de aminoácidos sulfurados e qualidade da carne de tilápias do Nilo na terminação, alimentadas com dietas suplementadas com metionina e taurina

Abstract

Methionine is a limiting amino acid and taurine is considered a conditionally essential amino acid for Nile tilapia fed plat-based diets. The aim of this study was to evaluate the growth performance, expression of genes related to sulfur amino acid metabolism and meat quality in finishing Nile tilapia fed extruded diets, supplemented with methionine and/or taurine. A control diet (CON) based on soybean meal containing 280 g kg-1 crude protein and 3050 kcal kg-1 of digestible energy, without methionine or taurine supplementation was elaborated. From the control diet, three more diets supplemented with methionine (MET), taurine (TAU) or methionine and taurine (MET+TAU) were elaborated. Fish were hand fed, two times a day, seven days per week, until apparent satiety, for 7-wk. Fish (n= 120, initial mean weight: 1199.1 ± 45.5 g) were distributed in a completely randomized design with four treatments and three replicates of 12 fish per floating net-cage. Fish fed diet MET t demonstrated higher (P <0.001) final body weight than those fed diet TAU, with no difference between the final body weight of fish fed diet MET+TAU. Fish fed diet MET+TAU showed improved (P = 0.022) feed conversion compared to fish fed other diets Fish fed diets MET, TAU and MET+TAU showed higher (P <0.001) fillet yield and higher (P <0.005) protein content in the body and fillet than those fed the control diet. Fish fed diets MET and MET+TAU showed lower (P <0.001) plasmatic triglycerides than those fed diets control and TAU. Fish fed diet MET+ TAU showed less yellowish fillet coloration 21 days after slaughter in relation to those fed control and MET diets. The expression of mRNA of cystathione beta synthase (CBS) gene and cystathione dioxigenase (CDO) demonstrated a higher expression of mRNA in fish fed diets supplemented with methionine (P <0.001). The expression of mRNA gene of adenylyl cyclase gene (AHCY) was higher in fish fed the TAU diet compared to fish fed other diets (P = 0.01). It was concluded that isolated or combined supplementation of methionine and taurine improves performance and protein retention by modulating sulfur amino acid metabolism and body and fillet lipid deposition. In addition, taurine showed a positive effect on meat quality, preserving the color of the Nile tilapia fillet.