Sophora alopecuroides supplementation improves growth performance of Simmental cattle by enhancing feed utilization...

This study examined the impacts of Sophora alopecuroides supplementation on growth performance, nitrogen (N) and energy utilization, methane (CH₄) emissions, serum indices, rumen fermentation, and bacterial community in Simmental cattle. Twenty-four 6-month-old male Simmental cattle (170.00 ± 1.07 kg) were randomly assigned to 4 treatments: control (basal diet, 0 mg/kg group) and basal diet with 150, 300, or 450 mg/kg body weight (BW) of S. alopecuroides supplementation. The 74-d trial included a 14-d adaptation and a 60-day experimental phase. Results showed that S. alopecuroides supplementation quadratically increased dry matter intake (DMI), average daily gain (ADG) and final BW (P < 0.05), while reducing feed conversion ratio (FCR) (P = 0.001). S. alopecuroides supplementation also quadratically increased the apparent digestibility of DM, organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) (P < 0.05). Additionally, supplementation at 300 mg/kg reduced urinary N excretion and improved retained N, compared to the 0 mg/kg group (P < 0.05). S. alopecuroides supplementation quadratically enhanced gross energy intake (GEI) and energy balance (EB) (P < 0.05), while tended to quadratically increase digestible energy intake (DEI; P = 0.064), and metabolic energy intake (MEI; P = 0.087). Furthermore, the content of serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were quadratically enhanced by S. alopecuroides supplementation (P < 0.05). Moreover, S. alopecuroides supplementation linearly increased the proportion of acetate in the rumen (P = 0.028), with trends towards a higher acetate/propionate ratio (P = 0.083) and lower concentration of propionate (P = 0.086). Alpha diversity indices (Chao1) were higher in the 300 mg/kg group than in the 0 mg/kg group (P < 0.05). Rikenellaceae RC9-gut group and Ruminococcaceae NK4A214 group were significantly increased in the 300 mg/kg group, and positively correlated with EB (P < 0.05); while WCHB1-41 was decreased in the 150 and 300 mg/kg group, and positively correlated with UE and urinary N excretion (P < 0.05). The functional prediction results indicated that the pathways related to 'Xenobiotics biodegradation and metabolism', 'Biosynthesis of other secondary metabolites', and 'Infectious disease: bacterial' were significantly enriched in the 450 mg/kg group, while 'Pantothenate and CoA biosynthesis', 'C5-branched dibasic acid metabolism', and 'Valine, leucine and isoleucine biosynthesis' were significantly enriched in the 300 mg/kg group (P < 0.05). Co-occurrence network analysis revealed that S. alopecuroides supplementation at 450 mg/kg reduced the complexity and stability of the rumen bacteria network. In conclusion, dietary supplementation with S. alopecuroides at 300 mg/kg improved the growth performance of Simmental cattle by enhancing nutrient digestibility, N utilization, energy metabolism, and serum antioxidant levels. Excessive levels (450 mg/kg) negatively impacted the complexity and stability of the rumen bacteria community. These findings suggest that while S. alopecuroides can be beneficial at optimal levels, careful dose management is essential to avoid adverse effects on rumen microbiota and overall animal health.