Dietary baicalin supplementation enhances growth performance in fattening Hu sheep via dual modulation of immunity and gastrointestinal microbiome-metabolic crosstalk

BACKGROUND: Baicalin is a bioactive flavonoid from Scutellaria baicalensis Georgi with antioxidant, anti‑inflammatory and antibacterial properties. However, its bitter taste and susceptibility to ruminal degradation limit its practical use in mammals. Enteric coating technology might overcome these limitations by enabling targeted intestinal release. This study investigated effects of dietary supplementation with baicalin and coated baicalin on rumen fermentation, gastrointestinal microbiota, immune function and growth performance in Hu sheep. RESULTS: Thirty-six lambs with similar body weight (33.01 ± 2.68 kg) were randomly assigned to three groups (4 replicates per group, 3 sheep per replicate). The control group was fed basal diet (CON) while treatment I (BAI) and treatment II (C-BAI) groups were fed a basal diet supplemented with 0.1% baicalin and coated baicalin, respectively. After a 60-d feeding trial, baicalin and coated baicalin supplementation improved total weight gain and average daily gain compared with CON group (P < 0.05). In addition, BAI and C-BAI groups exhibited higher total antioxidant capacity (P < 0.05) and catalase activity (P < 0.05) with associated lower malondialdehyde levels (P < 0.05). Immunoglobulin G and anti-inflammatory cytokines interleukin-4 (IL-4) were also increased (P < 0.001). Notably, IgM, IL-10 and IL-4 in the C-BAI group exceeded those of the BAI group (P < 0.001). Microbiome analysis revealed that baicalin supplementation enriched abundance of beneficial bacterial taxa including Firmicutes and Lachnoclostridium (P < 0.05) and reduced potential pathogen abundance, e.g., Treponema and Ralstonia (P < 0.05). The C-BAI group also showed increased abundance of the beneficial Bradyrhizobium compared with CON (P < 0.05). Metabolomic analysis revealed that baicalin altered propionate and tyrosine metabolic pathways (P < 0.05), while coated baicalin modulated penicillin metabolism and glyceride metabolism in jejunum (P < 0.05) increasing ATP production. Overall, these results indicated enhanced nutrient metabolism and gut health in the presence of dietary baicalin. CONCLUSIONS: Dietary supplementation with baicalin and coated baicalin improved growth performance, antioxidant status, immunity and beneficially modulated the microbiome-metabolome crosstalk in Hu sheep. Notably, uncoated baicalin exerted more pronounced effects on growth performance and supported a role for baicalin as a potential and functional feed additive.