الفهرس 
INTRODUCTION.Only 14 pages are availabe for public view
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Abstract
In recent years, the feed additives are being studied extensively with great interest which have desirable effects by improving the animals performance and health, through enhancing digestibility of the feed materials, promoting growth rate, increasing feed conversion and preventing disease. Extensive using of antibiotics lead to imbalance of the intestinal microflora, appearance of resistant bacteria and also drug residues in the bird for that tend to restrict using of antibiotics and using natural feed additives. from this feed additives probiotics and prebiotics. Collibacillosis in Egypt and all over the world is considering one of the most chronic bacterial disease.
So this study aim to control the collibacillosis by using some feed additives as probiotics and prebiotics and studying their effects on biochemical & immunological parameters, as well as DNA damage and histopathological studies.
This study done on one hundred and twenty (120) chicks, one day old, commercial Hubbard chicks obtained from Dakahlia Poultry Company, divided equally into 6 groups of each 20 chicks.