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Tannic acid (TA) is a plant-derived compound with well-known astringent properties and a long history of use in controlling diarrhea.
Objective: In this study, we explored how different levels of TA (0, 0.01%, 0.05%, and 0.25%) added to low-protein diets influence growth performance, intestinal barrier function, and gut microbiota in weaned piglets, particularly under an Escherichia coli (E. coli) challenge.
Methods: A total of 35 weaned piglets were randomly assigned to five experimental treatments: an unchallenged control group, an E. coli K88–challenged control group, and three E. coli K88–challenged groups fed low-protein diets supplemented with TA at 0.01%, 0.05%, or 0.25%. The E. coli K88 challenge was applied near the end of the trial. Body weight was recorded weekly, while feed intake and diarrhea were monitored daily using a fecal scoring system. At the end of the experiment, blood and intestinal samples were collected to evaluate intestinal morphology, intestinal gene expression, and gut microbiota composition.
Results: The group receiving 0.05% TA showed increased body weight, daily gain, and feed intake, along with lower feed-to-gain ratio and diarrhea incidence. Following E. coli K88 challenge, diarrhea appeared in the challenged control group but was largely prevented in the higher TA doses groups. Serum markers indicated improved immunity in TA-treated piglets, with higher IgM and IgA levels and lower inflammatory markers compared to challenged controls. Intestinal morphology and barrier function were enhanced by 0.05% TA, with higher ileal villi, improved villus-to-crypt ratio, and increased expression of tight junction and water channel genes. The TLR4/MyD88/NF-κB inflammatory pathway was activated in challenged pigs but moderated in 0.25% TA-treated animals. E. coli challenge reduced microbial diversity and altered community composition, whereas MTA increased beneficial genera such as Ruminococcaceae_UCG_005, Ruminococcaceae_UCG_002, and Ruminococcaceae_NK4A214_group. Correlation analyses showed that these microbial changes were linked to improved growth and immune responses.
Conclusion: Taken together, these findings indicate that supplementing low-protein diets with 0.05% of tannic acid, without the use of antibiotics, can alleviate E. coli–induced intestinal disturbances and enhance immune function in weaned piglets.
Zhou W, Wang C, Jian Q, Zhou H, An Z, Feng Y, Chen H, Qin Y, Yao T, Liu H, Kong Z, Yin Y, He L, Li T, Tang W. Tannic acid-mediated gut microbes for enhanced intestinal immunity in Escherichia coli-challenged weaned piglets. J Anim Sci. 2025; Oct 7:skaf342. https://doi.org/10.1093/jas/skaf342