Follow up the antibodies titer against Newcastle disease virus in broiler breeders using ELISA test

The study period carried out from 25 April 2018 till 21 May 2019 through the rearing and production period including totally of 24000 birds (20800 females, 3200 males). The number of tested blood samples was 452 divided to 255 samples at the rearing period, 143 samples at the production period and 54 samples of offspring. The results of antibodies titer in the sera of non-vaccinated broiler breeders obtained by ELISA showed the maternal derived antibodies titer for 28 samples at 0-5 week/day of age was 5716±612.7, this titer decreased gradually at 3-1 week/day age till to 1075±234) Then the titer was elevated increasingly after vaccination with both live attenuated and inactivated vaccines and reach to peak 37512±2049.4 at 20-1 week/day age. Whereas the bimodal graduation of antibodies titer showed at production period till to end of study. The mean of maternally antibodies titer in the tested sera of the offspring chicks 0-1 week/day that hatched from parent flocks at 32, 39 and 48 weeks of age was 9012±872.4, 6591±368.1 and 4831±982.7 respectively. Thus, we concluded the repetitive vaccination of broiler breeders flock with live vaccine as well as inactivated vaccine is very necessary in endemic areas and ELISA is a good serological test for following, checking and monitoring of immune status of poultry flocks periodically.