Abstract: The haemoglutination inhibition test were carried out for supervising the decreasing and increasing rule of serumantibody and yolkantibody titers of serum and yolk samples collected on 0、7、14、21、28、35 days from the 160days old preunimmunized laying hens after being immunized with avian influenza oilemulsion bivalent (H5 and H9) inactivated vaccines. The results revealed that the H5, H9 Serumantibody HI titer was first appeared on the 7th day, and the midHI titer was appeared on the 14th day, and the peak HI titer was maintained from the 21th day to and after the 35th day. Comparing with the Serum-antibody, the appearance of yolk-antibody titers was relatively hanged behind about 7 days, and the peak HI titers of both Serum-antibody and yolk-antibody were appeared on 28th day and sustained till and after 35th day, and the HI titers of yolk-antibody was also corresponding with that of Serum -antibody from the 28th day. Our results suggested that the HI titers of yolk-antibody could be used as the substitution of Serum -antibody after the lay hen immunized 28 days. The result was also laid a foundation for further studies and using the yolk antibodies (IgY) of AI. 

Key words: AI; serum-antibody; yolk-antibody; decreasing and increasing rule of HI titer; detection