Iranian Journal of Veterinary Medicine 189 IJVM (2015), 9(3): Growth performance parameters in chicken experimental coc- cidiosis treated with Diclazuril and Clopidol: The need for as- sessing new anticoccidial resources Asadi Iraee, H. 1 , Asadi Iraee, M. 2 , Youssef, M.R. 3 , Abouhosseini Tabari, M. 4* 1 DVM, Private Veterinarian Practitioner, Amol, Iran 2 Young Researchers Club, Islamic Azad University, Babol Branch, Babol, Iran 3 Department of Veterinary Parasitology, Faculty of Veterinary Medicine, Islamic Azad University, Babol Branch, Babol, Iran 4 Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran Abstract: BACKGROUND: Coccidiosis is recognized as the parasitic disease that has the greatest economic impact on poultry pro- duction. Modern poultry production is largely dependent upon anticoccidials. OBJECTIVES: The aim of the present study was to determine and compare the effcacy of two chemical anticoc- cidials (Clopidol and Diclazuril) on oocyst shedding and their probable effects on growth performance and feed effciency of broilers in experimental coccidiosis. METHODS: One hundred and twenty Ross 308 one day old broilers were randomly as- signed into 4 groups: CON+, infected with Eimeria mixed oo- cysts but not medicated; CON-, not infected and not medicat- ed; CLO, infected and medicated with Clopidol; DIC, infected and medicated with Diclazuril. Chickens in all groups except negative control were inoculated by mixed sporulated oocysts of pathogenic Eimeria at the end of the 3 rd week of age. Oocyst shedding was counted using a Mc Master counting chamber. Body weights, body weight gains, and feed conversion ratio were determined on weekly basis. RESULTS: Obtained results showed that Diclazuril was more effective in reducing oocyst shedding than Clopidol. As expected, mean body weight in the positive control group was lower than other groups. But surprisingly, no signifcant difference was found between Di- clazuril or Clopidol treated birds and positive control group, at the end of the experiment. In comparison of weight gain in different treatment groups except for the 4 and 5 th week, no signifcant difference was found in different groups. In the last week of the experiment, difference in weight gain between groups was not signifcant. According to feed conversion ra- tio (FCR) results, anticoccidial supplementation did not have any signifcant effect on improving FCR. CONCLUSIONS: It is reported that some anticoccidials reduce feed consumption and feed conversion. It seems that neither of the present synthetic anticoccidials is completely satisfactory in controlling coccid- iosis economic losses and new strategies are urgently required. Key words: coccidiosis, Diclazuril, Clopidol, growth performance, broilers Correspondence Abouhosseini Tabari, M. Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran Tel: +98(11) 44265008 Fax: +98(11) 44271054 Email: m.abuhosseini@ausmt.ac.ir Received: 11 March 2015 Accepted: 6 July 2015 189-194