Effects of dietary lipid levels on growth, feed utilization, body composition and antioxidants of juvenile mud crab Scylla paramamosain (Estampador)

This study was carried out to determine the effects of dietary lipid levels on growth performance, feed utilization, body composition and antioxidant parameters of juvenile mud crab (Scylla paramamosain). Five isonitrogenic and isoenergetic experimental diets (45% crude protein) containing 0%, 3%, 6%, 9% and 12% added oils (named L0, L3, L6, L9 and L12, respectively) were fed to triplicate groups of 20 crabs (initial weight 11.53 ± 0.52 g, carapace width 3.92 ± 0.14 cm) for 8 weeks. The results showed that the survival, final body weight, carapace width, specific growth rate and molting frequency of crabs fed diet L6 were significantly higher than those of crabs fed diet L0, L3 or L12 (P < 0.05). The highest feed conversion ratio and the lowest protein efficiency ratio were both observed in crabs fed diet L0 (P < 0.05). The maximum voluntary feed intake was found in crabs fed diet L3 (P < 0.05). The lipid contents of whole body and hepatopancreas increased remarkably with the elevated dietary lipid levels (P < 0.05). The proportions of saturated fatty acid and monounsaturated fatty acid of the hepatopancreas were significantly higher in crabs fed diet L0 (P < 0.05). The fatty acid composition of the hepatopancreas and muscle was consistent with those in the diets. In the hepatopancreas, crabs fed diet L12 accumulated the highest concentration of malondialdehyde than other groups (P < 0.05), and the activities of antioxidant enzymes (superoxide dismutase, glutathione S-transferase and glutathione peroxidases) were all enhanced with the increased dietary lipid levels (P < 0.05). The results suggested that a proper dietary lipid level of 8.52%-11.63% (optimum 9.5%) could maintain solid growth performance and antioxidant capacity of juvenile mud crab S. paramamosain.