Effects of dietary lipid level on growth, fatty acid profiles, antioxidant capacity and expression of genes involved in lipid metabolism in juvenile swimming crab, Portunus trituberculatus

The regulation of lipogenesis and lipolysis mechanisms related to consumption of lipid has not been studied in swimming crab. The aims of the present study were to evaluate the effects of dietary lipid levels on growth, enzymes activities and expression of genes of lipid metabolism in hepatopancreas of juvenile swimming crab. Three isonitrogenous diets were formulated to contain crude lipid levels at 5 center dot 8, 9 center dot 9 and 15 center dot 1 %. Crabs fed the diet containing 15 center dot 1 % lipid had significantly lower growth performance and feed utilisation than those fed the 5 center dot 8 and 9 center dot 9 % lipid diets. Crabs fed 5 center dot 8 % lipid had lower malondialdehyde concentrations in the haemolymph and hepatopancreas than those fed the other diets. Highest glutathione peroxidase in haemolymph and superoxide dismutase in hepatopancreas were observed in crabs fed 5 center dot 8 % lipid. The lowest fatty acid synthase and glucose 6-phosphate dehydrogenase activities in hepatopancreas were observed in crabs fed 15 center dot 1 % lipid, whereas crabs fed 5 center dot 8 % lipid had lower carnitine palmitoyltransferase-1 activity than those fed the other diets. Crabs fed 15 center dot 1 % lipid showed lower hepatopancreas expression of genes involved in long-chain-PUFA biosynthesis, lipoprotein clearance, fatty acid uptake, fatty acid oxidation, lipid anabolism and lipid catabolism than those fed the other diets, whereas expression of some genes of lipoprotein assembly and fatty acid oxidation was up-regulated compared with crabs fed 5 center dot 8 % lipid. Overall, high dietary lipid level can inhibit growth, reduce antioxidant enzyme activities and influence lipid metabolic pathways to regulate lipid deposition in crab.