Microbial bioactive complex supplementation is associated with gut microbial fermentation and feed conversion in weaned piglets

Improving feed efficiency while maintaining gut stability is a key nutritional objective during the post-weaning period in piglets. This study investigated the effects of dietary supplementation with a microbial bioactive complex (MBC), composed of Pediococcus pentosaceus CACC616, Lactobacillus reuteri CACC607, L. dextrinicus CACC889, L. pentosus CACC891, and Saccharomyces cerevisiae CACC699, on feed efficiency and gut microbial fermentation in weaned piglets. The complex was produced via solid-state fermentation (SSF), enabling the co-delivery of viable microorganisms and fermentation-derived metabolites. A total of 34 piglets were randomly assigned to either a basal diet (control) or the same diet supplemented with MBC for 33 days. The MBC contained approximately 2.4 × 10⁹ CFU/g of lactic acid bacteria and 5.17 × 10⁶ CFU/g of yeast and was included in the diet at 0.5%. MBC supplementation significantly improved feed conversion ratio (p < 0.05) and reduced average daily feed intake, indicating enhanced feed utilization efficiency without adverse effects on health-related blood parameters. The constituent strains exhibited desirable probiotic and safety characteristics, including tolerance to acidic and bile salt conditions, adhesion to porcine intestinal epithelial cells (IPEC-J2), absence of hemolytic activity, and low biogenic amine production. Microbial analysis revealed that taxa enriched in the MBC-treated group, including Succinivibrio and Succinivibrionaceae UCG-001, are associated with carbohydrate fermentation and succinate-producing pathways. Collectively, these findings indicate that dietary supplementation with MBC is associated with improved feed conversion and changes in fermentation-related gut microbial taxa in weaned piglets, supporting its potential application as a functional feed additive in swine production.