Comprehensive Characterization of <i>Acer truncatum</i> Leaf Extract: Identification of Systemic Metabolites and Effects on Performance, Antioxidant Status, and Intestinal Microbiota in Laying Hens

ABSTRACT The demand for natural feed additives is considerably increasing in the antibiotic‐free feed era. Therefore, identifying abundant and cost‐effective plant resources is essential. This study was conducted to evaluate the potential applicability of A. truncatum leaf extract (ATLE) in laying hens based on its chemical composition, in vivo absorption, and physiological functions. A total of 1734 metabolites were identified in ATLE, and the free radical‐scavenging activities were approximately half that of Trolox in vitro. Analysis of serum medicinal chemistry indicated the absorption of 80 prototypically active ingredients (e.g., epicatechin and geniposide ). In vivo studies indicated that dietary ATLE supplementation increased laying rate and decreased feed conversion ratio; quadratic regression analysis recommended an optimal 0.6%–0.7% ATLE range; elevated plasma superoxide dismutase (SOD) activity and reduced glutathione (GSH) content; enhanced intestinal glutathione peroxidase (GSH‐PX) and SOD activities and GSH content and upregulated the expression of Gpx3 , Sod2 , Prdx3 , Mgst1 , and Gsr ; decreased malondialdehyde (MDA) levels in the liver and increased Sod1 and Prdx3 expression; reduced ovarian MDA levels, increased GSH content and GSH‐PX activity, and upregulated Gpx3 , Mgst1 , and Sod2 expression at 0.6%; and modulated cecal microbiota, enhanced beneficial bacteria (e.g., g_Akkermansia and o_Lactobacillales ), and exhibited tissue‐specific correlations with antioxidant markers. Collectively, ATLE showed excellent free radical‐scavenging ability. The active ingredients were effectively absorbed and significantly improved the production performance of aged laying hens by enhancing antioxidant defense and modulating the gut microbiota. Therefore, ATLE can be used as a viable nutrient to increase laying performance of aged hens.