Effects of Dietary Lysophospholipids on Growth Performance, Hepatic Lipid Metabolism, Intestinal Health and Dietary Lipid Levels of Largemouth Bass (Micropterus salmoides)

This study investigated the effects of dietary lysophospholipids on growth performance, hepatic lipid metabolism, intestinal health, and dietary lipid levels of largemouth bass. The 56-day experiment included five groups: CON (0% lysophospholipids), LL50 (0.05% lysophospholipids), LP50 (0.05% lysophospholipids—0.5% oil), LP100 (0.1% lysophospholipids—1.0% oil), and LP200 (0.1% lysophospholipids—2.0% oil), with 3 replicates (30 fish/replicate) per group. The results showed that compared with the CON group, dietary supplementation of 0.05% lysophospholipid had no significant effect on the growth performance of largemouth bass, but increased the crude protein content and decreased the crude lipid content in the whole body. An amount of 0.05% lysophospholipid improved hepatic lipid utilization efficiency. Specifically, this supplementation level promoted serum lipid transport (increased serum HDL-C content and decreased triglyceride and LDL-C contents), and enhanced hepatic lipid metabolism by regulating the expression of lipid metabolism-related genes (fas, hsl, and acc) and the levels of lipid metabolites (phosphatidylcholine and fatty acids), thereby reducing hepatic triglyceride content. In addition, 0.05% lysophospholipid improved intestinal health by increasing lipase activity and intestinal villus height, up-regulating the expression of the anti-inflammatory gene (tgf-β1) and tight junction protein genes (claudin-1, claudin-4, and zo-1), and down-regulating the expression of the pro-inflammatory gene (tnf-α). In terms of dietary lipid reduction, supplementation with 0.1% lysophospholipid allowed a 1% reduction in dietary lipid level without affecting the growth performance of largemouth bass, whereas at the same level of lysophospholipid supplementation, a 2% reduction in dietary lipid level resulted in decreased growth performance of largemouth bass. These findings provide theoretical support for the practical application of lysophospholipids, and demonstrate that reducing dietary lipid inclusion by adding lysophospholipids helps to reduce feed costs and improve aquaculture economic benefits.