The HI antibody was 6.40log2,and the peak value appeared in week 3 to 5.The HI antibody could maintain 4.88log2 in week 19.Then the second immune injection adopted 0.5 mL/bird,the effective antibody could last 20 weeks.

• 3 mL/羽首免后10 d HI抗体就可达到6.；40 log2；3-5周达到高峰期；至免疫17周后(19周龄)HI抗体水平仍然维持在4