Effects of Zanthoxylum bungeanum Leaves on Production Performance, Egg Quality, Antioxidant Status, and Gut Health in Laying Hens

Zanthoxylum bungeanum leaves (ZBL) are a phytogenic feed resource, but their energy value and functional effects in laying hens are not well defined. Two experiments were conducted. In Exp. 1, 96 healthy 38-week-old Roman Pink laying hens were allotted to either a control diet or a diet containing 5% ZBL (eight replicates, six hens per replicate) to determine apparent metabolizable energy (AME) using an indicator method (7 d adaptation, 3 d collection). The AME and nitrogen-corrected AME of ZBL were 5. 46 and 5. 33 MJ/kg, respectively. In Exp. 2, 832 healthy 41-week-old hens were randomly assigned to diets supplemented with 0, 1%, 2%, or 3% ZBL (8 replicates, 26 hens per replicate) for 8 weeks after 1 week adaptation. Dietary ZBL at 1% to 3% did not affect production performance (p > 0. 05), but increased albumen height linearly (p < 0. 05) and improved yolk color at 2% and 3% (p < 0. 05). ZBL increased serum albumin (p < 0. 05) with a linear tendency (p = 0. 065), and elevated serum IgA and IgM linearly (p < 0. 05). Serum total antioxidant capacity and total superoxide dismutase were increased (p < 0. 05) with significant linear and quadratic responses (p < 0. 05), while serum malondialdehyde was reduced (p < 0. 05). In the liver, 3% ZBL increased total antioxidant capacity (p < 0. 05), hepatic catalase activity was decreased in all ZBL groups (p < 0. 05), and hepatic malondialdehyde was reduced (p < 0. 05). Cecal acetate increased linearly (p < 0. 05), and propionate and butyrate increased with both linear and quadratic dose responses (p < 0. 05). ZBL improved small intestinal morphology, especially duodenal villus height (p < 0. 05). Gut microbiota was remodeled, with a marked reduction in norankₒ_WCHB1-41 and increases in Ruminococcus, Pseudoflavonifractor, and several Coriobacteriales and Erysipelatoclostridiaceae taxa. Overall, ZBL provides usable energy and, at 2–3% inclusion, enhances egg quality, antioxidant status, humoral immunity, short-chain-fatty-acid production, and intestinal health without compromising laying performance.