The Effectiveness of Immunostimulants on NDV Genotype VII and IBDV Infection in Broiler Chickens

The present study was conducted to investigate the pathogeneicity of Newcastle Disease Virus (NDV) genotype VII.1.1 "NDV-CHICKEN-EGY-ALEX-NRC-2020" strain in combination with Infectious Bursal Disease Virus (IBDV) "IBDV/Egypt/Qalubia/17" and/or some commercial immunostimulants (Lector ® and Orego ® ) in commercial broiler chickens.The pathogenicity studies parameters included the effects on protection, growth performance and clinico-pathological changes.The results indicated that, immunostimulants can keep maternal immunity longer where lector ® was the best; the decline in HI titers also indicates that bird groups not contract ND natural infection.The results of performance parameters after immunostimulants administration and challenged with IBDV at 14-days of age and NDV GenotypeVII.1.1 at 21-days of age in broiler chickens proved that administration of Lector ® and Orego ® solution had positive effect on average body weight gain and feed conversion rates than control non medicated groups; where the Lector medicated groups showed higher rates of average weight followed by Orego ® medicated groups.Regarding signs and mortality in infected groups IBD signs varied from mild in lector ® , moderate in Orego ® while sever signs were in non-medicated group.The mortalities began at 5 th day post-challenge (pch) in non-medicated groups with total 10-20%; while the mortalities in NDV began at 3 rd day pch in group non-medicated with 50% to reach 100% mortality rate in 7 th pch.At necropsy both IBD and NDV infection lesions were found in dead birds of all challenged groups.Chicken groups challenged by IBDV or NDV after treatment with Lector showed milder histopathological changes than Orego solution and non-treated groups showed the most sever lesions.Chicken groups challenged with both virulent IBDV and NDV either treatment with Lector ® or Orego ® solution or non-treated showed no marked difference in histopathological lesions.The results of total and differential leucocytes indicated that lector had a great high effect in WBCs levels specially lymphocytes and monocytes.In conclusion the used immunostimulants are of low value against IBD and ND virulent viruses challenge.In conclusion, is recommended to apply a strict hygienic measures and suitable vaccination programmes to protect chickens against both IBD and NDV infection as the current control and prevention regimes, including vaccines and vaccination protocol are not adequate against either single or mixed infection infections with IBD and/or ND.