The broilers were randomly allotted to four treatment groups (Con, DEX, P8, and DEX+P8 groups) with 10 replicates per group (10 broilers per replicate). Broilers in the Con and DEX groups were fed a basal diet. Broilers in the P8 and DEX+P8 groups were fed a basal diet containing 1 × 108 CFU/g P8. At 16 days of age, broilers in the DEX and DEX+P8 groups were injected with 3 mg/kg body weight DEX (200 μL), whereas broilers in the Con group were injected with an equal volume of saline.