A commensal Lactobacillus-based probiotic consortium isolated from healthy pig feces alleviates weaning stress in nursery pigs via modulation of gut microbiota and metabolites

This study aimed to evaluate the effects of a commensal <italic>Lactobacillus</italic>-based consortium (CLC) on growth performance, gut microbiota, and metabolite profiles in weaned pigs. A total of 48 newly weaned pigs (7.32 ± 0.96 kg body weight) were randomly allotted to one of two dietary treatments based on a randomized complete block design with initial body weight as the blocking criterion. Dietary treatments were a basal nursery diet based on corn–soybean meal (CON) and CON + 0.02% CLC (10¹⁰ CFU/kg of diet) containing <italic>Lactobacillus amylovorus, L. johnsonii, L. mucosae, L. reuteri, and L. ruminis</italic>. Pigs fed with the CLC exhibited significantly improved body weight gain and feed efficiency compared to controls. Although hematological parameters remained unaffected, serum levels of AST were reduced by CLC supplementation, with trends toward decreased ALT and LDH. Lipid profiles improved with elevated HDL and reduced LDL, alongside significant reductions in serum malondialdehyde (MDA) and cortisol levels. Gut microbiota analysis revealed that CLC supplementation increased the abundance of <italic>Lactobacillus</italic> and Prevotellaceae, with a reduced abundance of Clostridiaceae. Metabolomic profiling showed that CLC supplementation enriched short-chain fatty acids, particularly lactate and acetate, as well as elevated levels of amino acids (methionine, glycine, alanine, threonine, and valine) and key intermediates such as malate, succinic acid, and conjugated linoleic acid. Taken together, dietary supplementation with CLC enhanced growth performance and systemic health in weaned pigs, potentially by mitigating oxidative stress and cortisol responses while promoting beneficial shifts in the gut microbiota and metabolome during the critical post-weaning period.