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Background: The aim of the present study was the comparison of humoral and cell-mediated immunity in ‎broilers fed with different levels of zinc during a coccidiosis challenge.‎Methods: One hundred and forty-‎four one-day-old broiler chicks were used with three ‎dietary zinc ‎(40, 120 and 200 mg/kg). At 14 d of age, all birds were inoculated orally with 5×103 sporulated oocysts of E. Tenella. ‎At ‎2, 22, 32, 42 ‎days of age, the blood serums were tested for ‎antibody titer against‎ Newcas­tle disease vaccine, using ‎the standard HI test. On day 42 the sum of nitrite ‎and nitrate based on the reduction of nitrate ‎to nitrite by cadmium ‎and white blood cell count (WBC) using a hemocytometer were measured.Results: At 42 d, levels of ‎120 and 200 mg significantly (P< 0.05) increased the antibody titer in compare with the control. The peak response of CBH was observed at the level of 200 mg Zn/kg diet. Also both level of 120 and 200 mg Zn/kg diet increased WBC count and sum of nitrite and nitrate‎ in serum compared with the control.Conclusion: The levels of 120 and 200 mg Zn/kg diet could be considered as a non-pharmacologic booster of immunity in broilers chicks infected with E. Tenella.

Background: The aim of the present study was the comparison of humoral and cell-mediated immunity in broilers fed with different levels of zinc during a coccidiosis challenge. Methods: One hundred and forty- four one-day-old broiler chicks were used with three dietary zinc (40, 120 and 200 mg/kg). At 14 d of age, all birds were inoculated orally with 5×103 sporulated oocysts of E. Tenella. At 2, 22, 32, 42 days of age, the blood serums were tested for antibody titer against New-castle disease vaccine, using the standard HI test. On day 42 the sum of ni-trite and nitrate based on the reduction of nitrate to nitrite by cadmium and white blood cell count (WBC) using a hemocytometer were measured. Results: At 42 d, levels of 120 and 200 mg significantly (P< 0.05) increased the antibody titer in compare with the control. The peak response of CBH was observed at the level of 200 mg Zn/kg diet. Also both level of 120 and 200 mg Zn/kg diet increased WBC count and sum of nitrite and nitrate in serum compared with the control. Conclusion: The levels of 120 and 200 mg Zn/kg diet could be considered as a non-pharmacologic booster of immunity in broilers chicks infected with E. Tenella.