Monitoring of law of rise and decline of AI hemagglutination inhibition antibody in broiler chickens and waterfowl induced by H_5 subtype vaccines against avian influenza

Abstrcat The monitoring plan for AIV H_5 subtype specific antibody titers was implemented for continuous 5 months in broiler parent chickens immunized with inactivated H_5N_2 oil-emulsion vaccine. The results showed that high maternal antibody titers of HI antibody in parent broiler chickens at 7 days old declined to very low level during 14 days. So the first immunization for broiler must be conducted in 10-day-old, and the boost immunization must be conducted at (100 days) after first vaccination immnine and the immunization program for broiler would be determined depending on the level of brioler's maternal antibody and the quality of vaccines. In this study, the level of commercial ducks' and geese' maternal antibody, and that induced by first immunization and boost immunization were monitored for a long time. The results showed that the aquatic birds immunized at 3-day-old elicited good immune resposes and the level of AIV specific antibody mounted to high titers at 25-(30 days) after first immunization, but could not be maintained for a long time. So the best time for boost immunization was conducted at 21 days after first active immune at titers at 25-30 days after first immunization, but could not be maintained for a long time. So the best time for boost immunization was conducted at 30 days after first active immune.