Abstract:[Objective] The aim of this study was to evaluate the effects of Macleaya cordata extracts (MCE) instead of antibiotics on growth performance, caecum microbes, short chain fatty acids (SCFAs) and tight junction mRNA expression in yellow-feathered broilers.[Methods] A total of 300 one-day-old Wenshi new yellow broilers No. 2 with similar body weight were randomly allotted to 5 groups, with 6 replicates and 10 broilers per replicate. Broilers in control group were fed a basal diet (NC) and broilers in antibiotic group (ANT), fed a basal diet with 50 mg/kg Nosiheptide and 50 mg/kg chlortetracycline, while those in the treatment groups were fed a basal diet supplemented with 200, 400 and 800 mg/kg MCE. The experiment was lasted for 60 days.[Results] The addition of 400 mg/kg MCE to replace antibiotic growth promoter in yellow-feathered broilers diet significantly reduced (P<0.05) the feed conversion ratio, and significantly increased (P<0.05) the length of the cecum. Dietary supplementation with MCE significantly increased (P<0.05) the cecal Firmicutes and Clostridium cluster XIVa counts and significantly decreased (P<0.05) the Escherichia coli counts. Supplemented with 400 and 800 mg/kg MCE to replace AGPs significantly increased (P<0.05) the cecal total short-chain fatty acids, acetic acid and butyric acid, and 400 mg/kg MCE significantly increased the branched-chain fatty acids, including isobutyrate and isovalerate (P<0.05). Supplementation with MCE in no AGPs diet significantly increased the expression of Claudin-1, JAM2 and ZO-1 (P<0.05). And MCE instead of AGPs significantly increased the expression of JAM2 (P<0.05). However, the addition of MCE to the diet significantly reduced the gene expression of MUC2, MUC5ac and MUC13 (P<0.05).[Conclusion] The MCE replace dietary AGPs of yellow-feathered broilers improves the growth performance promotes caecum growth, and help to establish a stable and healthy intestinal barrier which through increasing the number of beneficial bacteria, SCFAs concentration and regulate the expression of tight junction proteins expression. The optimal addition amount of MCE under this experiment is 400 mg/kg.