killed and live vaccine

Live and killed (Oil Base) Vaccines are different vaccines. Live vaccine is mostly used for priming and killed vaccines in long time birds like breeders and layer birds are used for long term immunity. EDS, Avian influenza are usually used as killed vaccine,because for EDS it is assumed that priming has been done from field so only oil base vaccine is done. For AI vaccine it is mostly used as killed vaccine, but live vaccine can also be used which is avoided due to risk of emergance of new strains by recombination or gaining virulaance. Rest all vaccines are used both live 1st and then followed by killed vaccine. Further details can be obtained from study of literature for mechanism of immunity in birds. Live vaccines give immunity for shorter time in comparison to killed vaccines. Many other factors play role in maintainance of immunity, like heat stress, toxins, some immunodepressant like IBD, Merek's disease, CAV etc. Some killed vaccines (Oil base or water base) are also used as primary vaccine for AI and IBD.
Maqsood Haider Jaffery