Effects of the diet based on soybean meal supplemented with soy lecithin on growth, biochemical parameters and digestibility of nutrients in grouper, Epinephelus lanceolatus

The feeding trial was designed to establish the effects of the diet based on soybean meal (SBM) supplemented with soy lecithin on growth, biochemical parameters and digestibility of nutrients in grouper, Epinephelus lanceolatus. Soy lecithin at 10 g kg−1 was incorporated into the control diet that contained SBM [substitution of 40% fish meal (FM) protein]. Together with the lecithin‐free control diet and the FM‐based reference diet, three diets were administered to triplicate groups of fish (initial weight: 68.59 ± 0.09 g) in a recirculation system for 6 weeks. After the feeding experiment, the fish were fed the same diets with 5 g kg−1 chromic oxide as a marker to measure the digestibility. Growth performance of the fish was not (p > 0.05) affected by dietary treatments. The highest hepatic total lipid content was observed in fish receiving the control diet, followed by fish receiving a 10 g kg−1 lecithin‐supplemented diet and lowest in fish receiving the FM diet. Plasma transaminase activities were raised in fish fed the control diet compared with other dietary groups. The apparent dry matter digestibility was highest in fish fed the FM diet, followed by fish fed the 10 g kg−1 lecithin‐supplied diet and poorest in fish fed the control diet. The results demonstrated that the supplementation of dietary soy lecithin in the SBM‐based diet showed significant functions in improving the digestibility of nutrients and liver health in giant grouper. Supplementation of soy lecithin at 10 g kg−1 in SBM‐based diet is recommended for the species.