Effects of curcumin on growth performance, intestinal morphology and microbiota, and liver transcriptome in Asian yellow pond turtle (Mauremys mutica)

This study investigated the effects of dietary curcumin supplementation at different concentrations on the growth performance, intestinal morphology and microbiota, and liver transcriptome of Mauremys mutica . Healthy turtles were randomly assigned to five groups: a control group (C0, 0 mg/kg curcumin) and four treatment groups (C100, C200, C400, and C800) receiving curcumin at 100, 200, 400, and 800 mg/kg diet, respectively. Each group consisted of three replicates (30 turtles per replicate), and the trial lasted for 60 days. The results demonstrated that dietary supplementation with 100, 200, and 400 mg/kg curcumin significantly improved both weight gain rate (WGR) and specific growth rate (SGR), with the 200 mg/kg group showing the highest activities of α-amylase, trypsin, and lipase compared to the control group. Curcumin supplementation also significantly increased intestinal villus height, muscular thickness, and goblet cell counts per villus, indicating an improvement in intestinal morphology. Furthermore, curcumin modulated the gut microbiota composition by increasing the relative abundance of Prevotellaceae_unclassified while decreasing Desulfobacterota, Proteobacteria, Edwardsiella , Bacteroides , and Negativibacillus . Transcriptomic analysis of liver tissues revealed 215, 422, 265, and 243 unique DEGs in the 100, 200, 400, and 800 mg/kg groups, respectively. These DEGs were primarily enriched in immune-related pathways such as the PI3K-Akt, and TNF signaling pathways, as well as metabolism-related pathways including the PPAR signaling pathway, nucleotide metabolism, and various amino acid metabolism pathways. Collectively, these findings indicate that curcumin enhances growth performance and digestive capacity, improves intestinal morphology and digestive enzyme activity, modulates microbial community, and regulates hepatic gene expression related to immune and metabolic function in M. mutica . Based on regression analysis (R 2 > 0.5) of key indicators—including WGR, SGR, FCR, and the activities of trypsin and lipase, as well as malondialdehyde (MDA) content—and with no significant effect on survival, the optimal dietary inclusion level of curcumin for M. mutica was estimated to be between 199.74–266.73 mg/kg. • Dietary curcumin significantly enhanced the growth performance and intestinal digestive enzyme activities of Mauremys mutica . • Curcumin modulated the gut microbiota composition and improved intestinal morphology. • Curcumin suppressed pro-inflammatory pathways and enriched metabolism-related pathways.