Abstract
This study evaluated the feasibility of replacing soybean lecithin (SBL) with lysophospholipids (LYLs) in the diet of Pacific white shrimp, Litopenaeus vannamei. Five isonitrogenous diets were formulated as the control diet with 15 g/kg soybean oil and 15 g/kg SBL inclusion (LYL-0), three SBL-substituted diets with 1/3, 2/3, and 3/3 of SBL substituted with the same amounts of LYL (LYL-0.5, LYL-1, and LYL-1.5), and a low-lipid diet (LYL-L) with 5 g/kg soybean oil and 15 g/kg LYL inclusion. Then, shrimp (1.6 ± 0.1 g) were fed with the above diets for 8 weeks. The LYL-1.5 group presented significantly higher weight gain (WG) than the control (p < 0.05), but no significant difference was observed in WG and feed conversion ratio (FCR) between the control and LYL-L group, or between the LYL-L and LYL-1.5 group (p > 0.05). Whole-body lipid levels were found to be substantially increased in the LYL-1 and LYL-1.5 groups compared to the control, while hepatopancreatic lipid content and lipid droplet area (Oil Red O stain) were significantly lower in the LYL-1, LYL-1.5, and LYL-L groups (p < 0.05). Serum high-density lipoprotein cholesterol (HDL-C), lipoprotein lipase (LPL), hepatic lipase activities, and the apparent digestibility of crude lipid were significantly increased in the LYL-1 and LYL-1.5 groups (p < 0.05). In contrast, serum triglyceride (TG) and total cholesterol (TC) levels were significantly decreased in the LYL-1.5 and LYL-L groups (p < 0.05). In summary, under the present conditions, the complete replacement of SBL with LYLs improved growth performance and lipid metabolism and enabled a 10 g/kg reduction in dietary lipid level for Pacific white shrimp.