Effect of dietary lipid levels on performance, body composition and fatty acid profile of juvenile white seabass, Atractoscion nobilis

The objective of this study was to determine the optimum dietary lipid level of white seabass, Atractoscion nobilis, which is one of the most important species in California and Baja California for sport and commercial fisheries. Triplicate groups of fish were fed for 50 days with isonitrogenous experimental diets formulated with increasing lipid levels (2.6, 7.4, 11.6, 15.3 and 19.4% lipid) using menhaden oil as the lipid source. A commercial diet (CD, 49.9% crude protein, 14.7% lipid) was also fed to triplicate groups of fish. Survival throughout the growth trial ranged from 89 to 100% but the survival of fish fed the 2.6% lipid and the commercial diet was significantly less than the rest of the diets. Final mean body weight, feed conversion ratio (FCR), and nitrogen retention efficiency (NRE: N gain/N intake) were significantly greater for diets 15.3 L and 19.4 L compared to the rest of the treatments. Daily feed intake (DFI) was variable (3.5 ± 0.08 to 8.6 ± 0.03) and significantly affected by dietary treatment. Lipid content of whole body, muscle and liver increased with increasing dietary lipid levels. Muscle and liver fatty acid (FA) composition reflected dietary FA profiles. Tissue n−3 and n−6 highly unsaturated fatty acids (HUFAs) content increased in direct proportion to dietary lipid levels.