Fermented Chinese Herbal Medicines Improve Intestinal Health in Livestock and Poultry via Microbial Transformation of Bioactive Compounds and Anti-Inflammatory Mechanisms

Intestinal inflammation, underpinned by gut dysbiosis, epithelial barrier dysfunction and dysregulated TLR4/NF-κB-mediated innate immunity, represents a major constraint on livestock production efficiency and animal welfare.Traditional Chinese herbal medicines (TCHMs) possess multi-component, multi-target anti-inflammatory profiles and favourable safety margins; however, their therapeutic efficacy is limited by poor oral bioavailability, extensive first-pass metabolism and substantial pharmacokinetic variability.Microbial fermentation can remodel herbal constituents through polysaccharide depolymerisation, flavonoid glycoside hydrolysis, phenolic acid liberation and alkaloid/tannin modification, potentially yielding metabolites with improved bioaccessibility and intestinal anti-inflammatory activity.This narrative review synthesises current evidence on fermentation-mediated phytochemical transformation of Chinese medicinal herbs and the intestinal health effects of the resulting preparations in production animals.Fermentation microorganisms, metabolic profiles and conditiondependent phytochemical transformations are critically examined and integrated with tissue-level protective mechanisms encompassing gut microbiota remodelling, shortchain fatty acid metabolism, epithelial tight-junction reinforcement, suppression of aberrant TLR4/MyD88/NF-κB signalling and pathological NLRP3 inflammasome activation, as well as Nrf2-dependent antioxidant defence.Evidence obtained directly from fermented herbal preparations in production animals is explicitly delineated from that extrapolated from general probiotic or short-chain fatty acid (SCFA) literature.Importantly, much of the mechanistic evidence remains preclinical, and few studies have validated efficacy, optimal dosing or safety under commercial production conditions.Finally, a "strain-ingredient-metabolite-microbiota-host" mechanistic framework is proposed to guide the standardisation of fermentation protocols, quality control and the veterinary application of fermented TCHMs.