Continuous fermentation-derived fecal microbiota transplantation improves intestinal barrier function and reshapes gut microbiota in weaned piglets

Weaning diarrhea in piglets poses a serious threat to the healthy development of the swine industry and is closely associated with gut microbiota dysbiosis. Fecal microbiota transplantation (FMT), as an effective strategy for modulating intestinal microecology, remains underexplored in swine production, particularly regarding the systematic evaluation of fecal microbiota suspension prepared via continuous fermentation on piglet health. In this study, fecal microbiota suspensions derived from adult pigs and piglets were prepared using a continuous fermentation system. A 28-day feeding trial was conducted with 18 piglets randomly assigned to three groups: control (CON), adult pig-derived FMT(FMT-A), and piglet-derived FMT(FMT-P). Growth performance, diarrhea incidence, gut microbiota, fecal short-chain fatty acids (SCFAs), and serum immune/inflammatory cytokines were measured. The results showed that compared with CON, both FMT treatments significantly increased average daily gain (ADG) and reduced diarrhea rate (P < 0.05), with FMT-A exhibiting superior effects to FMT-P. FMT improved intestinal barrier function, as evidenced by reduced serum levels of endotoxin (ET) and D-lactic acid (D-LA), raised immunoglobulin G (IgG) and anti-inflammatory cytokine interleukin-10 (IL-10), and lowered pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) (P < 0.05). FMT-A significantly reduced diamine oxidase (DAO) and increased immunoglobulin M (IgM) and immunoglobulin A (IgA) (P < 0.05). 16S rDNA sequencing revealed that FMT reshaped the intestinal microbiota: FMT-A enhanced microbial uniformity, FMT-P improved richness; both tended to increase beneficial Lactobacillus, with FMT-A significantly increasing Firmicutes(P < 0.05). Furthermore, FMT increased fecal propionic acid and decreased valeric acid (P < 0.05). This study demonstrates the efficacy of fecal microbiota suspension prepared via continuous fermentation technology in improving intestinal health and growth performance of piglets, providing a novel strategy for developing standardized, stable, and active microbe-based interventions, and laying a foundation for further mechanistic understanding of FMT in livestock production.