Modulation of cecal microbiota and metabolite profiles by Zanthoxylum bungeanum seeds enhances antioxidant capacity and meat quality in Pekin ducks

Zanthoxylum bungeanum seeds (ZBS) are a bioactive-rich byproduct with potential as antibiotic alternatives, yet their systemic effects on waterfowl remain unclear. This study investigated the effects of dietary ZBS supplementation on growth performance, physiological status, meat quality, and the microbiome-metabolome profile in Pekin ducks. A total of 240 ducks (14-day-old) were assigned to four treatments containing 0% (CG), 1.5% (LG), 3.0% (MG), or 4.5% (HG) ZBS for 21 days. Trend analysis revealed a significant quadratic dose-response for growth performance (P< 0.05), identifying 1.5% as the optimal inclusion level for maximizing body weight. Physiologically, ZBS supplementation enhanced antioxidant capacity and liver function by linearly upregulating serum SOD, CAT, and GSH-Px activities while significantly reducing MDA, ALT, AST, and triglyceride levels (P< 0.05). Regarding meat quality, ZBS linearly increased breast meat redness (a*) and facilitated the linear deposition of glutamic acid and alpha-linolenic acid, mirroring the ZBS nutrient profile (P < 0.05). Consequently, this deposition optimized key nutritional indices, characterized by a linear reduction in the n-6/n-3 polyunsaturated fatty acid ratio (P< 0.01) and an improved BCAA/AAA ratio. Mechanistically, 16S rRNA sequencing indicated a beneficial filtering effect where ZBS reduced alpha diversity by suppressing inflammation-associated genera (Desulfovibrio, Fusobacterium) while enriching beneficial fermenters (Faecalibacterium, Barnesiella). Metabolomics further identified upregulated antioxidant and immunomodulatory metabolites, such as orsellinic acid and purine analogs, which correlated with improved host health. Collectively, ZBS functions as an ecological modulator that promotes liver health and meat nutritional value in a linear manner, while optimizing growth performance quadratically, with 1.5% identified as the optimal dosage.