Influence of different lipid sources on growth performance, oxidation resistance and fatty acid profiles of juvenile swimming crab, Portunus trituberculatus

The effects of dietary lipid sources on growth performance, feed utilization, hematological characteristics, antioxidant capacity and tissue fatty acid profiles were assessed in juvenile swimming crab (Portunus trituberculatus). Six isonitrogenous (approximately 45% crude protein) and isolipidic (approximately 8% crude lipid) experimental diets were formulated to contain fish oil (FO), krill oil (KO), palm oil (PO), rapeseed oil (RO), soybean oil (SO) and linseed oil (LO), respectively. 270 swimming crab juveniles (approximately initial weight 5.43 +/- 0.03 g) were randomly stocked and sorted into 270 individual rectangle plastic baskets in three cement pools. The results showed that crabs fed the diet containing KO had a significantly higher percent weight gain (PWG), specific growth rate (SGR) and molting ratio (MR) than those fed the other diets. Crabs fed the KO diet had the lowest feed conversion ratio (FCR) among all treatments, followed by the FO diet. However, survival, daily feed intake (DFI) and hepatosomatic index (HSI) were not affected by the dietary lipid sources. Crabs fed the FO and KO diets led to significantly higher glucose (GLU) concentration in hemolymph compared to that fed the vegetable oils (VOs) diets. Moreover, a significant elevation of total protein (TP), glucose (GLU) and low density lipoprotein (LDL) was observed in hemolymph of crabs fed the KO diet. The activities of total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC) as well as the content of glutathione (GSH) in hepatopancreas of crabs fed the KO diet had the highest value among all treatments. The minimum concentrations of MDA in hemolymph and hepatopancreas were observed in crabs fed the KO diet. The fatty acid compositions of tissues reflected that of diets and lipid sources. Crabs fed the FO and KO diets had significantly higher values of EPA, DHA and n-3/n-6 ratio in hepatopancreas and muscle than those fed the VOs diets. In summary, based on the growth response and antioxidant capacity in comparison to VOs even FO, KO appeared to be more effective and beneficial for juvenile swimming crab. This will provide reference for the development of the diet for the reproductive and developmental stage of swimming crab.