Effect of zinc on humoral and cell-mediated immunity of broilers vaccinated against coccidiosis.
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 5×10(3) 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.


CONCLUSIONS
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.
Department of Epidemiology and Parasitology, Faculty of Veterinary Medicine and Zootechnics, Armenian National Agrarian University, Yerevan, Armenia.
Sobhan
S
Sajadifar
Department of Veterinary, University of Applied Science and Technology, Institute of Science Applied Higher Education of Jahad -e- Agriculture, Isfahan, Iran.
Hadi
H
Miranzadeh
Department of Veterinary, University of Applied Science and Technology, Institute of Science Applied Higher Education of Jahad -e- Agriculture, Isfahan, Iran.
Milad
M
Moazeni
Coccidiosis; Immunity; Zinc