Immunological Detection of Avian Influenza(AI) and Application of the Developed Immune Procedure

Avian influenza has occurred many times in Shanxi province since 1998.It seriously influenced the healthy development of the poultry industry in this area.In terms of the situations,the study on the immunological detection of avian influenza was conducted in this work.Overall 2797 birds from 85 chicken flocks have been monitored on the maternal antibody of chicken and the changes of the antibodies of breeding birds and layers before and after immunization.The results showed that the maternal antibody of chicken is 3～5 log2.The titers of AI-H5-HI and AI-H9-HI were 5～6 log2 and 5.5～6.0 log2 detected at 30 days after vaccination,and 4.0～4.3 log2 and 4.1～4.4 log2 detected at 120 days after vaccination,respectively,which means the immune period is about 120 days for breeding hens and layers vaccinated in the normal procedure.The immune dosage of the AI vaccine for breeding layers was tracing tested.The results showed that if the bird was vaccinated with 0.5 ml at the age of 140～150 days old,the immune antibody declined to the critical line at the age of 260～270 days old,and need to be re～vaccinated during peak production.If the bird was vaccinated with 0.7～1 ml of the AI vaccine at the age of 140～150 days old,the immune antibody declined to the critical line at the age of 305 days old,and don't need to be re-vaccinated during peak production,and the maternal antibody of chicken is higher and remain longer time.In addition,the chicken's reasonable age for the first vaccination was determined and a comparatively scientific vaccination procedure was made basing on the level of the maternal antibody.When the maternal antibody of chicken is 3～4 log2,the first and second vaccinations should be done at 21～28 day-old and 140～150 day～old,respectively,and 120 days later for the third vaccination.When the maternal antibody of the chicken is about 5 log2,the ages of the first and second vaccinations is 35～40 and 140～150 day-old respectively,and the third vaccination age is still 120 days later after the second vaccination.This procedure has been already used in practice and good effects has achieved,which provide the protection for the healthy growth and safe production for the poultry industry.