Dietary lipid and n-3 long-chain PUFA levels impact growth performance and lipid metabolism of juvenile mud crab, Scylla paramamosain

Abstract

An 8 weeks feeding trial was conducted to evaluate the effects of dietary n-3 LC-PUFA levels on growth performance, tissue fatty acid profiles and relative expression of genes involved in lipid metabolism of mud crab (Scylla paramamosain). Ten isonitrogenous diets were formulated to contain five n-3 LC-PUFA levels at 7 % and 12 % dietary lipid levels. Highest weight gain and specific growth rate were observed in crabs fed the diets with 19.8 and 13.2 mg g-1 n-3 LC-PUFA at 7 % and 12 % lipid, respectively. Moisture and lipid contents in hepatopancreas and muscle were significantly influenced by dietary n-3 LC-PUFA at the two lipid levels. The DHA, EPA, n-3 LC-PUFA contents and n-3/n-6 PUFA ratio in hepatopancreas and muscle significantly increased as dietary n-3 LC-PUFA levels increased at both lipid levels. The expression levels of Δ6 FAD and ACO in hepatopancreas increased significantly, and expression levels of FAS, CPTⅠ and HSL were down-regulated, with increased dietary n-3 LC-PUFA regardless of lipid level. Based on weight gain, the n-3 LC-PUFA requirements of S. paramamosain were estimated to be 20.1 mg g-1 and 12.7 mg g-1 of diet at 7 % and 12 % dietary lipid, respectively. Over all, dietary lipid level influenced lipid metabolism, and purified, high-lipid diets rich in palmitic acid reduced the n-3 LC-PUFA requirement of juvenile mud crab.