This study was carried out to evaluate the efficacy of diclazuril in control of experimental Eimeria
tenella infection in broiler chickens. The trial was carried out on 75, day-old broiler chicks as they were
divided into 3 main equal separate groups (25 chicks; each). Group (1) was non infected non treated
(control positive), group (2) was infected non treated (control negative) and group (3) was infected and
treated with diclazuril. Groups (2 & 3) were orally received 1ml of an inoculum containing 100.000
sporulated oocysts of Eimeria tenella/ chick at 14 days of age. Chickens of group (3) were infected
and rations were supplemented with diclazuril from 1st day of experiment till the end of
experiment (42nd day). This study was assessed by effect of diclazuril on the performance parameters
including feed intake, body weight (BW), body weight gain (BWG), feed conversion ratio, feed
efficiency ratio and also mortalities in infected and treated chickens. Also, oocyst count (shedding) in
the dropping and lesion score was also recorded. The results revealed that group treated with diclazuril
showed great and significant improvement in (BW), (BWG) and (RGR) and also revealed the highest
reduction in mortalities, lowered number of oocysts and the lesion score, indicating that diclazuril is an
effective anticcocidial drug in treatment of E. tenella infection in chickens. Group provided with
diclazuril gave significant and satisfactory improvement in the assessment criteria when compared with
infected non treated group