Thesis (M.Sc.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

Regarding to the importance of protect the broiler chicks during the first period of life when their immune system still immature by improving of their immunity and also to improve the performance and their general health. The addition of antibiotic growth performance was used to improve the bird health and immunity. But because the incidence of antibiotic resistance which transferred to human through the meat, the use of AGP was banned.The importance of finding an alternatives to AGP became a necessary . Probiotics is one of this alternatives which improve the host immunity and health .From this point of view , the aim of the present study is investigate the effect of different probiotics on host immunity and determine the best one to used and the way in which it work . Therefore, the trail was conducted by 60bird in each group of control fed on basal diet only. Meanwhile, broilers in experimental groups received Bacillus subtilis10 ¹{u⁰⁰B⁰} CFU /gand Saccharomyces cerevisiae 10 ⁹CFU /g in addition to the basal diet for 42 d. The results of the study revealed that probiotics could modulate intestinal population .It was a significant increase in Lactobacillus population count in Saccharomyces , Bacillus and control group respectively .In addition to marked significant inhibition in E.coliand Salmonella count in the same groups respectively .Meanwhile, the modulation in intestinal beneficial bacteria aid in stimulation of SIgA secretion .SC group showed the best level of SIgA and serum IgA followed by BS group and C group

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