Exploring the effects of fermented Chinese herbal medicine on growth, cecal microbiota, metabolism, and muscle flavor-related compounds in fattening pigs

Fermented Chinese herbal medicines (FCHMs) are considered a promising natural feed additive in livestock production. While their potential benefits for growth and health are recognized, the mechanisms underlying their effects on meat quality traits such as flavor, and the mediating role of the gut environment, remain insufficiently explored. This study aimed to investigate the multifaceted effects of FCHMs on finishing pigs, with a focus on potential links between growth, cecal microbiota, metabolism, and muscle composition. A compound FCHM was prepared by fermenting 10 traditional herbs using selected lactic acid bacteria and yeast. Eighty Duroc × Landrace × Yorkshire pigs (30.0 ± 1.0 kg) were randomly assigned to a control group (CK, basal diet) or groups supplemented with 0.4% (GL), 0.6% (GM), or 0.8% (GH) FCHM. After a 110-day trial, FCHM supplementation was associated with improved growth performance. Pigs receiving FCHM showed significantly higher final body weight and average daily gain compared to the CK group, while the high-dosage group (GH) exhibited a reduced feed-to-gain ratio. Analysis of a subset of animals revealed that FCHM appeared to reshape the cecal microbiota structure, notably decreasing the relative abundance of Alloprevotella , Muribaculaceae , and Prevotella , while promoting genera such as Marvinbryantia , Veillonella , and Tyzzerella . Concomitant shifts in cecal metabolite profiles were observed, including altered levels of compounds like cytosine, hypoxanthine, L-malic acid, and uric acid. Furthermore, analysis of muscle tissue indicated that FCHM supplementation coincided with changes in the profile of fatty acids and volatile organic compounds, which are relevant to flavor. Preliminary integrative analysis suggested potential associations between specific microbial shifts, metabolite changes, and alterations in muscle flavor-related compounds. This exploratory study indicates that dietary FCHM supplementation can enhance the growth performance of finishing pigs and is associated with concurrent modifications in the cecal microbial ecosystem, metabolic profile, and muscle composition. The observed multi-level changes suggest potential associations between gut microbial alterations and muscle characteristics that may contribute to the effects of FCHMs. These findings provide a foundational framework for understanding the complex role of fermented herbs in animal nutrition and warrant further investigation to validate the proposed mechanisms.