الفهرس 
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Abstract
Necrotic enteritis is described as a disease of high economic loss which affects the health of broilers and also a threat to public health. It was caused by specific (NetB positive) strains of Clostridium perfringens which produce toxins in the intestinal tract of chicks. As the necrotic enteritis is a multifactorial born enteric disease that causes devastating losses to poultry flocks (up to 30%mortality in an infected flock) The subclinical form made less signs, with initial symptoms of reduced growth due to impaired nutrient utilization from damaged intestinal mucosa leading to problems with digestion and absorption, lower performance resulting in: weight loss, decreased feed conversion rate, and decrease production
The C. perfringens isolate was characterized and identified as C. perfringens type A through cultural, biochemical and pathogenicity characters. The C.perfringensisolate showed double zone of hemolysis (complete inner zone and incomplete outer zone of hemolysis) and was catalase negative. Further confirmation via pathogenicity test in mice, genia pig and broiler chicks were conducted.The antimicrobial profile of the isolate was determined by disc diffusion method and the isolate was found to be sensitive to Ciprofloxacin and Enrofloxacin.
The use of antibiotics in poultry nutrition to improve the growth, feed consumption, feed conversion rate and decreased mortality from clinical diseases is common. However, the proliferation of resistant bacteria via the food chain leads to a ban of the feed use of antibiotic growth promoters in livestock.EOs are volatile, natural, complex compounds characterized by a strong odor and formed by aromatic plants. EOs has anti septic effect as, bactericidal, virucidal fungicidal, and medicinal properties.
In this study, The MIC of thyme and clove EOson C. perfringens type A was evaluated in vitro using the agar dilution method.The MIC as determined by the agar dilution method was reported as 0.25% (equivalent to 2.5mg/ml) for thyme oil and 0.125% (equivalent to 1.25mg/ml) for clove oil
Based on MIC determination of both tested oils, an in vivo study was conducted to evaluate the use of EOs as feed additive for prevention and/or control of experimentally induced NE in 15-day old broiler chicks. The study, the tested EOs had no effect on palatability and/or feed consumption of broiler chickens. The use of EOs improved growth performance of broiler chickens especially when used as preventive feed additive continuously starting from 10 days of age. The EOs (especially thyme) reduced C. perfringens counts in intestine and alleviated intestinal damage caused by infection.
The use of plant extracted EOs directly as replacement for antibiotic growth promoter in poultry and to treat and/or prevent of NE and other enteric diseases affections need to be further evaluated. Also, the effect of prolonged used of EOs on feed palatability, poultry meat quality also need further investigation.