Dietary modulation of intestinal integrity and functionality in weaned piglets using short-chain fructooligosaccharides, essential oils and sodium humate

Early weaning is a critical stage in pig production, associated with intestinal and immunological stress that negatively impacts gut health and functionality. Given the global restrictions on antibiotic use, natural alternatives have gained increasing attention. This study aimed to evaluate the <i>in vivo</i> effects of short-chain fructooligosaccharides, essential oils and sodium humate on intestinal health in weaned piglets. Four dietary treatments were applied for 15 days to weaned piglets: a basal diet (control); short-chain fructooligosaccharides (scFOSs group); essential oils of <i>L. origanoide</i>s and <i>E. caryophyllata</i> with sodium humate (EOs-SH group); and a combination of scFOSs and EO of <i>Lippia origanoides</i> (scFOSs-EOLo group). Plasma cortisol and citrulline concentrations, gastrointestinal pH, intestinal histomorphology, intestinal disaccharidase activity, lymphocyte infiltration, goblet cells quantification, mucus bacterial adherence, volatile fatty acids, and microbiota composition were analyzed. No significant differences in cortisol concentrations were found among treatments (<i>p</i> = 0.514). EOs-SH group showed significantly higher citrulline levels (<i>p</i> < 0.01), indicating enhanced enterocyte function. The activity of lactase in the proximal jejunum (<i>p</i> = 0.03) and maltase in the duodenum (<i>p</i> = 0.045) increased in scFOSs and EOs-SH groups, suggesting improved digestive capacity. Mucus bacterial adherence was also greater in EOs-SH group (<i>p</i> = 0.039), reflecting enhanced mucosal protective quality. Gastrointestinal pH values were within physiological ranges for the age and intestinal segment evaluated. ScFOSs-EOLo showed a higher gastric pH than the control (<i>p</i> = 0.033), while no differences among treatments were observed in the remaining gastrointestinal regions (<i>p</i> > 0.05). No treatment effect was observed for villus height or villus height-to-crypt depth ratio, with shallower ileal crypts in EOs-SH and ScFOSs-EOLo groups (<i>p</i> = 0.003), indicating improved mucosal integrity. The lowest intraepithelial lymphocyte counts in the ileum were observed in scFOSs and EOs-SH groups (<i>p</i> = 0.033). Short-chain fatty acid concentrations did not differ statistically among treatments (<i>p</i> > 0.05). Microbiota analysis revealed that the EOs-SH treatment reduced potentially proinflammatory genera, including <i>Clostridium sensu stricto</i> 1, <i>Terrisporobacter</i>, <i>Prevotella</i> 115, and <i>Subdoligranulum</i>. scFOSs supplementation markedly increased <i>Lactobacillus</i>, consistent with its prebiotic effect (Padj<0.05 in all cases). In contrast, ScFOSs-EOLo treatment did not induce any relevant abundance microbial changes (Padj>0.05). All dietary treatments improved some intestinal health parameters, with more consistent responses observed in the treatment with EOs-SH. This supplementation enhanced intestinal integrity and functionality, offering a natural strategy to support gut health and resilience in antibiotic-free production systems.