الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
An experiment was conducted on 210 healthy one day old broiler chicks (Arbor Acers) to evaluate the potential protective effects of adding synbiotic (based on S. cerevisiae, B. subtilis, B. licheniformis, beta glucan and MOS), EO (anise, oregano and citrus peel) and their combination in broiler diets, as alternatives to the antibacterial (chlortetracycline HCL) and anticoccidial (diclazuril) feed additives, on the most important and devastating digestive tract infections (NE and coccidiosis), and their reflection on humeral immune response against Newcastle disease, infectious bronchitis, avian influenza and Gumboro disease vaccines.The experimental birds were divided into 7 groups (30 birds/ 3 replicates/ group) and treated as follow:Group1 (ABAC): Received antibacterial and anticoccidial drugs in diet for 35 d + challenged with Eimeria spp. and C. perfringens+ vaccination group 2 (SY): Received synbiotic product in diet for 35 d + probiotic product sprayed at hatchery + challenged with Eimeria spp. and C. perfringens+ vaccination.group 3 (EO): Received phytobiotic product in diet for 35 d + challenged with Eimeria spp. and C. perfringens + vaccination.Group4 (SYEO):Received synbiotic and phytobiotic products in diet for 35 d + probiotic product probiotic product sprayed at hatchery + challenged with Eimeria spp. and C. perfringens + vaccination.group 5 (CO): Challenged with Eimeria spp. + vaccination.group 6 (NE): Challenged with Eimeria spp. and C. perfringens+ vaccination.group 7 (CN): Control negative.To achieve the aforementioned goals we evaluated the following:177-Induced necrotic enteritis in broiler chicks (performance parameters, economic efficiency, lesion scoring and C. perfringens quantification).178- Induced coccidiosis in broiler chicks (oocyst shedding, dropping scoring, lesion scoring and litter scoring).179-Humeral immune responses to ND, AI, IB and IBD vaccines.4-Pathology of visceral organs (intestine, liver and pancreas) and immune organs (BF, thymus and spleen).Results can be summarized as follow:1-Feeding birds diets supplemented with EO alone or in combination with synbiotic has resulted in improving the total BW, WG and FCR in comparison with the NE group and the TFCR in comparison with ABAC group. However, they did not affect mortality rate of challenged birds in comparison with NE group.2- Treatment with essential oils alone or in combination with synbiotic numerically improved the economic parameters (TC, TR, NR and REE) and succeed in making their values closer to the ones recorded in CN group and higher than +ve challenge groups. While the synbiotic treatment showed significant (P<0.05) decline in these parameters.3-The Cp challenge was effective in inducing the NE gross lesions on different sections of small intestine, liver as well as increasing the cfu of Cp recovered from the jejunum in comparison with the negative control group.4-The synbiotics and/or EO were very effective in reducing the severity of lesions in small intestine and liver as well as the bacterial count in jujenum in comparison with the NE group.5-Feeding challenged birds synbiotics and / or EO were found to be effective in ameliorating the negative drawbacks of Eimeria spp. challenge as there were reduction in dropping scoring, oocyst shedding, lesion scoring, litter scoring and cumulative scoring in comparison with the NE group.6-The EO treatment was effective in enhancing humeral immune response against ND, AI, IB and IBD vaccination at various intervals of the experiment in comparison with NE and ABAC groups while, synbiotic treatment led to improving the immune response against IB and IBD vaccines and slowed the decline of maternal immunity against ND at first 2 weeks of experiment. The combination of synbiotics and EO showed significantly (P<0.05) higher antibody titer against ND (at 3rd week) and AI (at 2nd week) in comparison with NE group while; they showed numerical privilege in case of antibody titer against IBD and IB.7-The synbiotic treatment had significantly (P<0.05) decreased the relative weight of intestine, BF and thymus at 3 dpi to be closer to negative control group. The EO numerically declined relative weight of intestine, liver and immune organs. Moreover, the combination of synbiotic and EO led to significant (P<0.05) improvement in relative weight of thymus at 3dpi and spleen at 7 dpi.8- The Cp challenge increased the histopathological score in different intestinal sections and significantly (P<0.05) increased cum. coccidial infection in comparison with CN group. 9-The synbiotic and / or EO treatment reduced the histopathological cum. scoring of intestine and cum. infection by Eimeria spp. in comparison with NE and CO groups. In addition, they ameliorated the negative drawbacks of Cp challenge on liver histopathology same as antibiotic treated group.10- The synbiotic treatment showed milder histopathological lesions in BF, same as antibiotic treated birds, in comparison with NE group while, there was no obvious effect on histopathology of thymus in synbiotic and EO treated birds.7. CONCLUSION from the obtained results, we can conclude that: 1-Challenging broiler chicks with C. perfringens and Eimeria spp. had reduced performance and economic parameters, increased lesion scoring of organs & their relative weight.2-The EO treatment alone or in combination with synbiotic mitigated performance decline and monetary losses as well as they reduced both severity of lesions and proliferation of pathogenic agents. In addition, they decreased the drawbacks of coccidiosis challenge and enhanced humeral immune response.3-The synbiotic treatment ameliorated pathological drawbacks of the challenges on visceral organs and enhanced humeral immune response. However, it did not enhance the performance or economics.4-No significant enhancement in performance, economy, immunity and pathology were noted in antibacterial and anticoccidial treatment in comparison with EO treatment mainly and synbiotic treatment occasionally. In the light of these results, we recommend the following:1- Rearing broiler birds under high strict biosecurity measures with avoiding cofactors that initiate the NE and coccidiosis is the best tool in reducing the risk of those devastating diseases.2-The EO alone or in combination with synbiotics can be used in broiler diets as preventive agent to reduce NE and coccidiosis drawbacks, as alternatives to antibacterial and coccidiostats feed additives, hence declining prevalence of bacteria and Eimeria spp. resistance toward these compounds as well as, offering the consumers with healthy poultry products which are free from antibiotic residues.