Newcastle disease vaccination in layer flocks: Comparison of efficacy and Vaccine replication in high antibody titer

Newcastle disease is one of the most important diseases affecting various species of birds. Different live and killed vaccines are used to control the disease that has different tropisms and severity. One of the uses of this vaccine is its use during the breeding period of poultry. To investigate the effectiveness of titer increase and the possibility of proliferation of vaccine in the presence of high antibodies against Newcastle, in this study, five vaccines B1, Vitapest, I2, Lasota, Clone Lasota in 25 weeks’ old laying hens (in each group, 50 chickens) and were compared by drinking vaccination in five separate salons of the same age. Blood was taken from marked chickens before and three weeks after vaccination. Five days after vaccination, pharyngeal swabs were taken from the chickens to confirm the vaccine's proliferation. The HI test and the Real-Time PCR test was performed on sera and swabs, respectively. The HI titers did not significantly differ after three weeks. But in Lasota and I2 groups, it was able to increase the titer. Also, the distribution of titers was reduced only in the Lasota group. The proliferation test results showed that the Vitapest and B1 vaccine viruses were not detected in any samples. They cannot proliferate at this antibody level. The results showed that Lasota is a good offer for use in flocks with high antibodies against Newcastle. It is suggested that additional research be performed on cellular, mucosal, and challenge studies in this field.