Effects of adding a kind of compound bio-enzyme to the diet on the production performance, serum immunity, and intestinal health of Pekin ducks.

The use of bio-enzyme as feed additives holds significant potential. This study aimed to evaluate the impact of a kind of compound bio-enzyme supplementation (the main functional components are probiotics and astragalus polysaccharides) on the production performance, serum immunity, and intestinal health of Pekin ducks. A total of 126 male Pekin ducks were randomly assigned to three groups: a control group (CG, no additive), a low-dose group (LG, 0.1 % bio-enzyme), and a high-dose group (HG, 0.2 % bio-enzyme), with 6 replicates per group. Ducks were raised until 35 days of age, with weekly measurements of growth performance. At day 35, serum immunoglobulins were measured, carcass traits were recorded, and cecal contents were analyzed using 16S rRNA sequencing and metabolomics. Results indicated a significant increase in ADG (P = 0.049) and a decrease in feed-to-gain ratio (F:G) (P = 0.020) in LG and HG compared to CG during rearing. The HG showed a notable improvement in half eviscerated yield (HEY) (P = 0.023) and full eviscerated yield (FEY) (P = 0.008). No substantial changes were observed in immunological parameters (P > 0.05). The jejunal villus height to crypt depth ratio (VH/CD) significantly increased (P < 0.001) in LG, with notable improvements in duodenal (P = 0.001) and jejunal (P < 0.001) VH/CD in HG. The Shannon index (P = 0.042) and Pielou index (P = 0.038) of cecal microbiota were markedly lower in HG. Notable changes in the relative abundance of Firmicutes and Bacteroidota were observed in LG and HG. Differential bacteria and metabolites among the treatments were identified, and their correlations were analyzed. KEGG enrichment pathways of the metabolites were also identified. In conclusion, this bio-enzyme can improve production performance, intestinal wall structure, and microbiota in Pekin ducks. A 0.1 % concentration of this bio-enzyme is optimal for Pekin duck production.