Some studies on infectious larngotracheitis in layers

In this study, one hundred and twenty layer chickens either in freshly dead or diseased condition were collected from 12 field outbreaks of Il, T in commercial layer flocksrepresenting 174,000 chickens at different localities of EgyptianGovemorates with an age ranged between 14_ 65 weeks. The results obtained under experimental conditions could besummerized in the following :(1) Three isolates of ll..TV. could be isolated on CAM ofembryonated chicken eggs and identified serologically by AGP _ test, virus neutralization test and histopathologicallyby detection of characteristic oesinophilic intranuclearinclusion bodies . ( 2) This study revealed that the infection of n, T oceured with high existence during autumn and winter season, with anawide age range between 14 _ 65 weeks and most of the infection were oceured on flocks having largepopulation and showing sever respiratory SIgns.(3) Experimental infection was done to investigate thepathogenicity of the field isolated virus by three routes of inoculation were adopted by aerosol, intratracheal and incontact at the age of 12 weeks old in adose of 10 7EID 50 ,0.1 ml of the virus suspension per bird . ( 4) The clinical and post ... mortem findings in experimentally infected chikens were less in the severity than thatoccured in natural in! ection. The aerosed route revealedmore severe in the pathogenicity of inoculated virus inexperimentally in! ected birds than other routes ofG: