Evaluation of the half life of maternal antibodies against Avian Influenza (AI) in broiler and layer chicks in Qom

Background and Objectives:Influenza is an acute respiratory disease caused by infection with influenza viruses. Avian influenza (AI) viruses are members of the family Orthomyxoviridae. AI is a contagious viral infection that can affect several species of food producing birds as well as pet birds and wild birds.The aim of this study was tomonitorthe rate and half life of maternal antibodies against AI in broilerand layer chicks.Material And Methods:In order to determine AIV (H9N2) antibody titers in poultry , 400 blood samples (broiler and layer chicks 0-21 days) were collected from chicks in days 0, 5, 10 ,15 and 21.Determination of were taken and antibodies titre were determined by Hemagglutination Inhibition (HI) test using H9N2 strain of AI virus and estimation of half life of the antibodies.Analyzis of variance, Duncan s multyibe sange test. Mean HI titres (log 2) at different sampling intervals in the three groups were:1) Broiler flock from hens challenged with virus: 4.2, 2.7, 1.5, 0.4, 0.1, half life of maternal antibodies: 5.5 days.2) Broiler flock from hens vaccinated against the disease: 7.1, 5.4, 4.1, 2.3, 0.7, half life of maternal antibodies: 4.5 days.3) Layer flock: 4, 3.2, 2.7, 2.1, 0.5 half life of maternal antibodies: 11 days. The halves of antibodies in layer flock were significantly longer than broiler flocks and the difference between broiler groups were not statistically significant.Results And Conclusion:The results indicate that, the suitible time for vaccination of chickens with maternal antibodies in the broiler flocks is at 7 to 14 days of age (depending on their primary Ab titres), and at 14 to 21 days of age for the layer flocks.