Effects of dill powder (Anethum graveolens dhi) on performance and biochemical traits, immune response, blood cells and microbial population of cecum broilers after stress induced with dexamethasone were investigated. Two hundred and forty broilers were arrayed in completely randomized design with six experimental groups, five replications and eight broilers per replication. The experimental groups consisted of G1: control diet without additives, G2: control diet supplemented with 1.5% dill powder, G3: control diet supplemented with 1.5% dill powder under dexamethasone stress, G4: control diet supplemented with 3% dill powder, G5: control diet supplemented with 3% dill powder under dexamethasone stress, and G6: control diet under dexamethasone stress. After 31, 33, 38 and, 40 days, 2 mg/kg bodyweight (BW) dexamethasone was injected in right chest muscle in groups 3, 5, 6, and samples were taken after 35 and 42 days. Use of 3% dill powder reduced cecum microbial population significantly. Under dexamethasone oxidative stress conditions dill powder improved biochemical traits and the number of white blood cells significantly. Without stress induced by dexamethasone injection, use of 3% dill powder improved internal organs, increased the length of the digestive tract, improved weight gain, reduced FCR and improved antibody titers to Newcastle disease (ND) and avian influenza (AI) viruses. All levels of dill powder prevented negative impacts of dexamethasone on functional and biochemical traits. Thus, 3% dill powder has beneficial effects on performance, immune response, blood cell and microbial population, and could be used as a growth promoter and to prevent oxidative stress.
