الفهرس 
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Abstract
Objectives of the present study were to investigate the prevalence of clostiridium perfringens among broilers in Assiut Governorate, isolate and identify the causative agent associated with NE from various farm of different ages, detect the toxin genes in the isolate by The polymerase chain reaction assay (PCR), assaying the in vivo activity of zinc oxide (ZO-NPs) nanoparticles and amoxicillin against Clostridium perfringens isolated from broiler chicken and studying effect of ZO-NPs on growth performance, feeding behavior and intestinal morphology of broiler chickens. To achieve these objectives a total of 100 intestines from freshly dead and sacrificed broiler chicken (2 – 6 weeks old) were collected from private farms in Assuit Governorate. Collected samples were examined bacteriologically for possible recovery of C. perfringens. The efficacy of amoxicillin and different level of ZO-NPs in controlling experimental C. perfringens infection in broiler chickens were investigated in eighty four apparently healthy, one day old unsexed broiler chicks. The chicks were divided into 7 groups and all treatments were orally administrated group 1: un infected and untreared, group 2 : infected and un treated, group 3: infected and treated with amoxicillin, group 4, 5, 6 and 7 infected and received 10, 20, 30, 40 mg ZO-NPs respectivitly.
The current study revealed the following results:
• Out of 100 intestinal samples from diseased broiler chickens from privet farms in Assuit governorate only 37 samples were positive for C.perfringens with an incidence 37%.
• Multiplex PCR revealed that all recovered isolates were C. perfringns type A possessed α toxin gene only and indicated that type A was the most predominant etiology in the occurrence of NE in Assuit Governorate.
• ZO-NPs (10 to 40 mg/kg) exhibited a good antimicrobial activity against C. perfringens infection and effectively improve the clinical signs and histopathological changes of chickens in the NE disease model.
• Amoxicllin was effective against C.perfringensand reduce severity of clinical signs and PM lesion but has negative effect on body performance and significantly (P<0.05) decrease on weight gain (WG) and feed intake (FI) than the other groups but no significally effect on feed conversion rate when compared with infected group.
• Using ZO-NPs especially at 20 to 40mg/kg and amoxicillin have positive effect on feeding behavior and not affect drinking behavior of broiler chicken.
• Appropriate concentrations of ZO-NPs (20 - 40 mg/kg) improve growth performance in broiler and 20 mg/kg ZO-NPs is the optimal concentration in the feed of broilers.
• Dietary replacement with ZO-NPs in broiler feed especially at (20- 40 mg ) resulted in significant increase in villus height (VH) and villus crypt ratio (v/c) in all parts of the small intestine which indicate improvement of absorptive capacity of different nutrients and improved feed efficiency.