The application of corn bran (CB) to laying ducks via iso-energy and iso-nitrogen diets is rarely reported. Six hundred laying ducks (49 weeks) were equally assigned to five treatments: the control group with 0% CB and the other four groups with 3%, 6%, 9%, and 12% CB. The experiment lasted for 11 weeks. With the increase in CB, the relative weight of the proventriculus, gizzard, and ileum and the content and proportion of butyric acid in the cecal digesta were quadratically changed (p < 0.05), and the highest value was observed in the 12% CB group. Compared with the control, the 12% CB group showed decreased Deferribacteres, Spirochaetota, and Fusobacteriota at the phyla level and showed increased Pediococcus and decreased Bifidobacterium and Rikenellaceae_RC9_gut_group at the genus level (p < 0.10); the 12% CB group also showed 46 different metabolites, which are related to Lactobacillus and Pediococcus (p < 0.05). The 12% CB group showed increased (p < 0.05) albumen height at week 8 and yolk color at weeks 4 and 8 compared with the control. Overall, dietary inclusion of 3% to 12% CB is a possible feeding strategy for laying ducks under iso-energy and iso-nitrogen conditions, and the 12% CB group was more effective.
Keywords: corn bran; laying duck; laying performance; microbial communities.