Cornus officinalis extract modulates rumen microbiome and growth of lambs fed a high-concentrate diet

This study evaluated the effects of Cornus officinalis extract (1.5% DM) on growth performance, blood serum biochemical parameters, rumen fermentation and microbial composition in Hu lambs fed diets with different concentrate:forage ratio. Thirty-two lambs were assigned to a 2 × 2 factorial design receiving either a common basal diet or a high-concentrate diet with (CPC, HPC groups) or without (CBD, HCD groups) Cornus officinalis extract supplementation respectively. The results showed that lambs in CPC group had shown enhanced average daily gain and feed efficiency (P < 0.05). Blood serum biological parameters remained similar across all the treatments (P > 0.05), except for blood urea nitrogen (BUN) showing significant group differences (P < 0.05). Concentrations of tumor necrosis factor-alpha (TNF-α), lipopolysaccharide-binding protein (LBP), lipopolysaccharide (LPS), serum amyloid A (SAA), and Toll-like receptor 4 (TLR4) (P < 0.10) were significantly reduced in HPC, while TLR4 was notably decreased in CBD group (P < 0.05). Cornus officinalis extract significantly increased (P < 0.05) pH, total volatile fatty acids (TVFAs) and lactic acid levels under high concentrate diet. Furthermore, high-concentrate diets decreased the relative abundance of Bacteroidota and increased those of Firmicutes compared with the basal diet. While, HPC diet slightly decreased Firmicutes abundance and reduced α-diversity indices (P < 0.10). Correlation analysis between genus-level biomarkers and PICRUSt2-predicted enzymes revealed that enzymes related to lactate synthesis and the Embden-Meyerhof-Parnas (EMP) pathway were slightly increased in HPC group while antioxidation-related enzymes were more enriched in CPC group. Enzymes associated with volatile fatty acid synthesis were higher in HCD while carbohydrate hydrolysis–related enzymes were relatively higher in CBD group. Key genera, including Succinivibrio and Prevotella, remained stable across all treatments, whereas the abundance of Rikenellaceae_RC9_gut_group decreased under high-concentrate diet but was not affected by Cornus officinalis extract supplementation. Overall, supplementation with 1.5% Cornus officinalis extract promoted growth performance and positively altered composition and functional potential of ruminal microbiota ultimately contributing to improved metabolic balance in Hu lambs.