Partial Substitution of Fish Meal with Vegetable Protein Sources in a Diet for Sea Bass: Effects on Lipogenesis

Abstract

Three isoproteic (49.4%) and isolipidic (17.0%) diets were prepared: A control diet FM, in which protein was derived from fish meal and two experimental diets in which 70% of the fish meal protein was substituted with wheat gluten meal (WGM) or wheat gluten meal plus soybean meal (WGMsb), respectively. The essential limiting amino acids were added to satisfy the requirements of the species (Tibaldi et al., 1996). Three hundred and fifteen sea bass (initial weight = 23.9±0. 1g )were randomly divided into nine homogenous groups. The animals were reared in a closed recirculation system at 23.9 ◦ C and were fed ad libitum twice a day for 96 days. The fish were weighed at the beginning and the end of the experiment. The epatosomatic, viscerosomatic and mesenteric fat indices, and the body chemical composition were determined for four fish (AOAC, 1995). Six other fish from each trial were used to determine the fatty levels of the muscles, the liver and the mesenteric fat as described by Folch et al. (1957). The content of total cholesterol, triglycerides, phospholipids (Juaneda and Rocquelin, 1985) and the composition of fatty acid in the muscles (Lepage and Roy, 1984) were determined. The hepatic activity of glucose-6-phosphate deidrogenase (G6PD, EC 1.1.1.49), malic enzyme (ME, EC 1.1.1.40) and ATP citrate lyase (ACL, EC 4.1.3.8) were determined for the same animals (Dias, 1999).