Evaluation of the effects of diets containing different lipid levels for juvenile yellowfin seabream Acanthopagrus latus

Abstract

This study evaluated the effect of dietary lipid levels on growth, body composition, amino acid and fatty acid profile, and nutrient utilization of juvenile yellowfin seabream (Acanthopagrus latus). Six diets with different crude lipid levels at 7% (CL7), 9% (CL9), 11% (CL11), 13% (CL13), 15% (CL15), and 17% (CL17) were designed, and each diet was fed to 4 cages (50 fish per cage; 19.00 ± 0.01 g per fish) for sixteen weeks. Results indicated that weight gain (WG) and specific growth rate (SGR) were highest at 13% dietary lipid level, while feed conversion ratio (FCR) was lowest (P < 0.05). Intraperitoneal fat ratio (IPF) increased with increasing dietary lipid level from 7% to 17%. The lipid efficiency ratio (LER), lipid retention (LR), and nitrogen excretion (NE) decreased significantly with increasing dietary lipid level (P < 0.05). Crude protein and lipid of the whole body decreased or increased with increasing dietary lipid level, respectively (P < 0.05). The dorsal muscle and liver lipid content significantly increased with increasing dietary lipid (P < 0.05). With the dietary lipid increasing, total fatty acid content was significantly increased (P < 0.05). Results about the fatty acid profile of the whole body indicated that the proportions of C14:0, C16:1, C20:4, C20:5, and C20:6 were significantly decreased with increased dietary lipid level (P < 0.05). In contrast, the proportions of C18:0, C18:1, and C22:1 were increased with increased dietary lipid level (P < 0.05). The retention of fatty acids was decreased with increasing dietary lipid (P < 0.05). Form a nutritional, environmental, and economic point of view, 13% dietary crude lipid was recommended. Excess dietary lipid levels in diets negatively affect the structure of the liver, leading to lipid accumulation and inflammation development.