Comparative studies on efficacy of different vaccines against fowl typhoid in chickens

Abstract

Studies were conducted to compare the efficacy of live avirulent 9R vaccine, protein extracts and formalin- killed bacterinfor the protection of chickens against fowl typhoid. Vaccination of birds at 9 weeks of age using strain 9R with and withoutFreund's complete adjuvant resulted in 95 and 100% survivors, but the challenge strain persisted in the organs of 1 birdeach. The use of crude protein extract + adjuvant resulted in 100% survival rate along with total clearance of the challengestrain of Salmonella gallinarum from all the survivor birds. Addition of Freund's complete adjuvant during primaryvaccination resulted in higher antibody titres and survival rate. Killed bacterin without adjuvant gave minimum protectionagainst fowl typhoid.