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Abstract
The present investigation was undertaken to investigate some aspects related to Waning of Haemagglutination antibodies in both broiler and native flocks, epizootiology of different NDV outbreaks in broiler and native breed chicks., isolation and identification of NDV, and evaluation of different NDV vaccinal programs.
The current study revealed the following results :
- Hemagglutination – inhibiting (H I) Antibodies to ND virus were detected in 112 samples out of 217 chicken sera examined from the 3 different localities in Assiut, El mani and Sohag,
- The investigation of 50 outbreaks in native breed and broiler chicks revealed that ND outbreaks occurred at earlier age
(20 – 35 days) in broiler flocks than in native flocks
( 40 – 55 days ) of age .
- The respiratory clinical symptoms were more pronounced in broiler flocks than in native flocks. infection rate was 70% in broiler flocks, 22% in native flock.
- Isolation of 50 NDV outbreak in chicken embryos via allantoic cavity Resulted in high degree of mortality.
- All investigated outbreaks were identified by their HA activity which were confirmed by use Hem agglutination – inhibition test (HI). 10 isolates of ND virus were recovered they were typed as 7 isolates were velogenic and chloroform
Resistant and thermistable (at 60 and 120 minute) 56C and 3 isolates as a lentogenic and sensitive to chloroform and thermosensitive
(at 15 and 30 minute at 56c).
- Results of evaluation of different NDV vaccinal programs indicated that the combined vaccination with live and inactivated NDV vaccines were superior in protection (100%) against challenge, On the Other hand the combined vaccination with Avinew vaccine and inactivated NDV vaccine induced less protection rate (84%), while live NDV vaccine only induce protection rate (84%) more than the inactivated oil emulsion vaccines only in which the protection rate was (66%).