Effect of dietary lipid on growth performance, body composition, plasma biochemical parameters and liver fatty acids content of juvenile yellow drum Nibea albiflora

A feeding trial was conducted to determine the dietary lipid requirement and its effects on body composition, plasma biochemical parameters and liver fatty acids content in juvenile yellow drum Nibea albiflora. Six animal groups (initial weights, 17.7 ± 0.20 g) were fed isonitrogenous diets formulated with increasing lipid levels (52, 70, 94, 111, 129 and 153 g kg−1, labeled as L50, L70, L90, L110, L130, L150, respectively) using menhaden oil, twice daily to apparent satiation, for 8 weeks. The results showed that the weight gain and specific growth rate (SGR) of fish fed L130 and L150 lipid diets were significantly higher than those of the animals on the L50 lipid diet. The feed conversion rate (FCR) of fish fed the L130 lipid diet was significantly lower compared with the values obtained for the other groups. Hepatosomatic index (HSI) of fish fed the L90 lipid diet was significantly higher than that of animals on L150 lipid. Whole body and muscle lipid contents increased with increasing dietary lipid level, and the dietary fatty acid profile was reflected in liver tissue. Liver eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents in fish fed with the L150 diet were significantly higher compared with the values recorded in the other groups. Total highly-unsaturated fatty acid (HUFA) content in liver showed an increasing trend, whereas total saturated fatty acid (SFA) and mono-unsaturated fatty acid (MUFA) contents in liver tended to decrease with increasing dietary lipid levels. The plasma triglyceride and cholesterol contents of juvenile N. albiflora increased with the increasing dietary lipid level. Analysis by the broken-line model of percent weight gain indicated the optimal dietary lipid level in juvenile N. albiflora to be 120 g kg−1 of the diet.