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Abstract

This research had three complementary parts, in which the first investigated the broiler's protection on endemic areas with prevalence of v-NDV (genotype VI) by priming day-old broilers on farms with vectored-NDV vaccines and boosting with classical NDV Clone 30 versus priming and boosting on another farms with NDV Clone 30. The second part evaluated protection and immunity by a developed autogenous killed v-NDV in broilers against controlled challenge by genotype VI. The third part included seven broiler flocks on seven different farms located in v-NDV (genotype VI)-endemic area, introducing an additional subcutaneous dose of the developed autogenous vaccine at 6 days of age to their program of priming at d1 with vectored-NDV vaccine and boosting with NDV Clone 30 at d14. The additional autogenous vaccination was delivered to 100 tagged birds embedded in each flock of 22,000 birds. Results of the first part showed protection against genotype VI by NDV clone 30 alone and by combination of vectored-NDV vaccine and Clone 30 of 47.1 and 84.7%, respectively (P<0.05). Results of the second part showed that priming and boosting with the developed autogenous vaccine conferred a 100 % survival in Eimeria infected and non-infected birds that were challenged with v-NDV compared to 0.0% survivals in unvaccinatedchallenged controls (P<0.05). The acquired HI titers to hemaaglutinin and fusion proteins of genotype VI were significantly higher in the vaccinated birds compared to unvaccinated-challenged controls (P<0.05). The third part showed that the inclusion of an additional one dose of the autogenous NDV vaccine at 6 d of age improves protection in broilers by 6.5% compared to flocks deprived of this additional dose (P<0.05), and higher their HI titers at 21 d and 42 d of age.