Farmani A., Hedayati M.*, Yari M. and Ghabooli M. Department of Animal Science, Faculty of Agricultural Sciences, Malayer University, Malayer, Iran. *Corresponding author's email: hedayati@malayeru.ac.ir, mahvet77@gmail.com Objectives: The aim of this study was to evaluate the effects of dietary Piriformospora indica (PI), and clove essence (CE) and combination of them (synbiotic) on pH of digestive tract and intestinal length after oxidative stress in broiler. Materials & Methods: The experimental was performed with 320 male, one-day-old chicks (Ross 308) were fed completely randomly in 8 experimental groups and 5 replications and in each replication 8 chickens were fed with corn and soy-based diets and experimental groups included group 1: control diet (based on corn and soybeans without any feed additives), group 2: control diet with 0.2 cc dexamethasone injection, group 3: control diet with 11.6 cc CE, group 4: control diet with 10 mg PI, group 5: control diet with 11.6 cc of CE with 0.2 cc injection of dexamethasone, group 6: control diet with 10 mg PI and injecting 0.2 cc of dexamethasone, group 7: control diet with synbiotic contains: 10 mg of PI combination with 11.6 cc of CE, group 8: control diet with synbiotic contains:10 mg of PI and 11.6 cc of CE with 0.2 mg of dexamethasone injection. PI and CE were poured into chickens' water, during the raising period. After 31, 33, 38 and 40 days, 2 mg/kg BW of dexamethasone was injected in right breast muscle of experimental groups 2, 5, 6 and 8 in all replications, and after 35 and 42 day, samples were taken. Results & Conclusion: The result of pH of digestive tract that showed, n group has a significant effect on the pH of digestive tract. In length of intestine, the symbiotic group (t7) increased the length of deudenum, jeujenum and, ileum, and dexamthason group(t2), decreased them. This study showed the dexamthason decreased intestinal length and, symbiotic increased the intestinal length.
