BackgroundIntrauterine growth retardation (IUGR) is one of the major constraints in animal production. Our previous study showed that piglets with IUGR are associated with abnormal bile acid (BA) metabolism. This study explored whether dietary BA supplementation could improve growth performance and colonic development, function, microbiota, and metabolites in the normal birth weight (NBW) and IUGR piglets. A total of 48 weaned piglets (24 IUGR and 24 NBW) were allocated to four groups (12 piglets per group): (i) NBW group, (ii) NBW + BA group, (iii) IUGR group, and (iv) IUGR + BA group. Samples were collected after 28 days of feeding.ResultsThe results showed that dietary BA supplementation increased the length and weight of the colon and colon weight to body weight ratio, while decreased the plasma diamine oxidase (DAO) concentration in the NBW piglets (P< 0.05). Dietary BA supplementation to IUGR piglets decreased (P< 0.05) the plasma concentrations ofD-lactate and endotoxin and colonic DAO and endotoxin, suggesting a beneficial effect on epithelial integrity. Moreover, dietary BA supplementation to NBW and IUGR piglets increased Firmicutes abundance and decreased Bacteroidetes abundance (P< 0.05), whereasLactobacilluswas the dominant genus in the colon. Metabolome analysis revealed 65 and 51 differential metabolites in the colon of piglets fed a diet with/without BA, respectively, which was associated with the colonic function of IUGR piglets. Furthermore, dietary BA supplementation to IUGR piglets upregulated the expressions ofCAT,GPX,SOD,Nrf1,IL-2, andIFN-γin colonic mucosa (P< 0.05).ConclusionsCollectively, dietary BA supplementation could improve the colonic function of IUGR piglets, which was associated with increasing proportions of potentially beneficial bacteria and metabolites. Furthermore, BA shows a promising application prospect in improving the intestinal ecosystem and health of animals.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40104-023-00897-2.