Dietary Lipid Sources and Lysolecithin Modulate Growth, Lipid Metabolism, Hepatopancreatic Health, and Intestinal Microbiota in Macrobrachium rosenbergii

This study evaluated the effects of dietary lipid sources and lysolecithin (LL) supplementation on the growth performance, lipid metabolism, hepatopancreatic histology, and intestinal microbiota of Macrobrachium rosenbergii. A 56-day feeding trial was conducted using six isonitrogenous diets containing fish oil (FO), soybean oil (SO), or a 1:1 FO-SO blend (mixed oil [MO]), and each supplemented with or without 0.5% LL. Results indicated a significant interaction between dietary lipid sources and LL supplementation on growth performance (p < 0.05). The MO diet supplemented with LL yielded the highest growth rates, while LL supplementation significantly improved feed efficiency (p < 0.05). Regarding histological status, the dietary SO treatment induced a significant increase in hepatopancreatic lipid deposition (p  < 0.0001) and histological alterations, while LL supplementation reduced lipid deposition and improved hepatopancreatic morphology. Dietary lipid source significantly affected muscle n-3 polyunsaturated fatty acids (PUFAs; p < 0.01). However, a significant interaction between dietary lipid source and LL supplementation was observed specifically for hepatopancreatic total n-3 PUFA (p = 0.0053). Gene expression analysis confirmed that LL modulates lipid metabolism in a source-dependent manner, upregulating fatty acid oxidation pathways (Pparα and Cpt1) in FO groups while influencing synthesis pathways (FAS) in SO groups (p < 0.05). Furthermore, LL supplementation significantly altered the composition of intestinal microbiota, specifically enriching beneficial bacterial genera in dietary SO-treatment (p < 0.05). In conclusion, the dietary treatment combining MOs and LL showed beneficial effects on growth performance, lipid metabolism, and hepatopancreatic health in M. rosenbergii.