K.H Pirali Kheirabadi - Department of Pathobiology, Faculty of Veterinary Medicine, University of Shahrekord, Shahrekord, Iran
H Hassanpour - Department of BasicSciences, Faculty of Veterinary Medicine, University of Shahrekord, Shahrekord, Iran
H Nourani - Department of Pathobiology, Faculty of Veterinary Medicine, University of Shahrekord, Shahrekord, Iran
E Farahmand - Graduated from the Faculty of Veterinary Medicine, University of Shahrekord, Shahrekord, Iran. PhD Student of Poultry Science, Faculty of Veterinary Medicine, University ofTehran, Tehran, Iran

In order to determine the involvement of nitric oxide in the pathogenesis of coccidiosis induced by , 30 chickens were challenged with mixed four species of (E. acervulina, E. maxima, E.necatrix, E. tenella and ) Histopathological examination revealed a loss of epithelial tissue, congestion of blood vessels, severe muscular edema and necrosis of submucosa. The sum total of nitrite and nitrate was increased in the serum at 6, 10 and 14 days post-infection progressively, but was only significant ( < 0.05) at 10 and 14 days post-infection compared to earlier days. The nitrate amounts were also significantly higher at days 10 and 14. It can be concluded that infection by four species of stimulated NO production after infection. It is therefore possible thatNOis involved in the pathogenesis of coccidiosis

Nitrite and nitrate; coccidiosis , Eimeria;chicken