Effects of dietary phosphatidylcholine (PC) levels on the growth, molt performance and fatty acid composition of juvenile swimming crab, Portunus trituberculatus

A 50-day feeding trial was conducted to investigate the effects of dietary phosphatidylcholine (PC) levels on the growth performance, molt and body composition of the juvenile swimming crab, Portunus trituberculatus. Four isonitrogenous purified casein-based diets containing three PC levels and one commercial crude soybean lecithin (SL) level were formulated. A PC-deficient diet was designed as a control diet. Each diet was given to triplicate groups of 15 P. trituberculatus (initial weight, 25.4 ± 0.1 g/crab). The occurrence of molt death syndrome (MDS) was lowest in crabs fed the diet with 20 g/kg PC. The growth of crabs showed a significant positive correlation with dietary PC level, increasing linearly with PC level (P < 0.05), while growth performance was not significantly affected by SL supplementation. The highest growth performance was obtained in crabs fed the diet with 20 g/kg PC. Whole body triglyceride and cholesterol levels also increased linearly with increasing dietary PC level (P < 0.05). Serum triglyceride levels were significantly increased with SL supplementation (P < 0.05). Our results show that the n-3/n-6 ratios and 22:6n-3 concentrations in both hepatopancreas and muscle increased significantly with SL addition (P < 0.05). This study shows that PC supplementation in a casein-based diet had a significant growth-promoting effect on P. trituberculatus. Moreover, dietary SL had a greater effect on muscle and hepatopancreas fatty acid profiles than purified PC supplementation in diets.