Effect of Dietary Lipid Level on Growth Performance and Feed Utilization by Heterobranchus longifilis Fingerlings

A study was undertaken to determine the effect of the dietary lipid level on growth and feed efficiency of Heterobranchus longifilis fingerlings. Three isonitrogenous diets (35% crude protein) with increasing dietary lipid levels (7, 12.5 and 18% dry matter) were fed to triplicate groups of 20 fish (initial body weight 0.83±0.01 g) for eight weeks. Final body weight and Specific Growth Rates (SGR) of fish fed the 7 and 12.5% lipid diets was significantly higher than that of fish fed the 18% lipid diet. No significant differences in feed intake and feed conversion efficiency were observed among groups. At the end of the trial, protein content was significantly higher in fish fed the 7 and 12.5% lipid diets. The result of this trial indicate that an increase of dietary lipid level from 12.5 to 18% did not improve growth performance and feed efficiency of H. longifilis fingerlings. The inclusion of 18% of dietary lipid significantly reduced protein and energy retention efficiencies. It may be concluded that, under the experimental conditions, the increase of dietary lipid level beyond 12.5% had no beneficial effects.