This study investigated the effects of adding various concentrations of cholesterol and soy lecithin to feed on the growth performance, physiology, biochemistry, and serum metabolomics of Cyprinus carpio var. Two cholesterol concentrations (1 % and 2 %) and four soy lecithin concentrations (0 %, 2 %, 4 %, and 6 %) were employed, resulting in eight experimental groups (C1S0, C1S2, C1S4, C1S6, C2S0, C2S2, C2S4, and C2S6) that were cultivated for 60 days. The addition of C2S2 to the feeds enhanced the growth (WGR and SGR), antioxidant capacity (CAT, SOD, MDA, T-AOC, and GSH-Px), and lipid metabolism (TG, LDL-C, HDL-C, LPL, and HL) in C. carpio var. A significant interaction (P < 0.05) was observed between cholesterol and soy lecithin concentrations for WGR, SGR, and FCR, and a highly significant interaction (P < 0.01) was observed for CAT, SOD, T-AOC, GSH-Px, TG, LDL-C, and HDL-C in C. carpio var. Based on these results, three comparisons (C1S4-vs-C1S0, C2S2-vs-C2S0, and C2S2-vs-C1S2) were selected to analyze the serum metabolic profiles of C. carpio var. through LC-MS. The differential metabolites screened included amino acids and their metabolites, nucleotides and their metabolites, bile acids, fatty acids, carbohydrates and their metabolites. The metabolic pathways involved were purine metabolism, glycine, serine, and threonine metabolism, arginine and proline metabolism, and ABC transporter proteins. In summary, the interaction between cholesterol and soy lecithin significantly influenced the growth performance, antioxidant capacity, and cholesterol metabolism of C. carpio var. The most beneficial effects on growth and lipid metabolism were observed when both cholesterol and soy lecithin were added at a concentration of 2 %. The present study provides theoretical guidance for the appropriate concentrations of cholesterol and lecithin in aquafeeds.
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