الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Many respiratory viral diseases cause severe economic losses in chicken industry in broiler farms although used vaccination and biosecurity systems for controlling the diseases.
In this study, particular attention was directed for isolation and identification of some respiratory viruses involved in respiratory outbreaks in broiler farms as NDV, IBV and AIV. Which are major significance .
Newcastle disease is highly contagious disease of chicken caused by NDV or avian paramyxo virus type 1 (AMPV1), which classified as member of genus Avulavirus, subfamily Paramexovirinae, family Paramyxoviridae. Infectious bronchitis (IB) is a highly contagious upperrespiratory tract disease of chickens, IBV is a member of the family Corona viridae. Avian influenza (AI) is a highly contagious viral disease affecting several species of birds. It is caused by various serotypes of influenza A virus of the Orthomyxoviridae family.