Research And Application Of Prevention And Control Technology Of Avian Influenza In Egg Breeding Farm

In recent years,the breeding industry has developed rapidly.As a big province of chicke n breeding,Shandong province accounts for a large proportion of laying hens in China,and th e breeding level is high.However,with the expansion of breeding scale,the increase of breedi ng density and the extension of breeding period,the pressure of disease prevention and contro l of laying hens,especially laying hens,is becoming more and more serious.Among the com mon poultry diseases,Avian Influenza（AI）is the no.1 infectious disease that endangers the p oultry industry in China.The main measures to prevent this disease are effective vaccine imm unization,reasonable immunization procedure,immune effect detection and evaluation,and a sound biosafety system.The egg breeding farm of our company has been under great pressure from the preventio n and control of avian flu.Among 151 samples of dead embryos and weak chicks of commerc ial chickens collected from a certain batch,13 H9 AIV positive samples were detected,and th e positive rate was 8.61%.Dead chicken avian influenza in different periods of chicken group of epidemiological investigation showed that the chicken group of ill chicken H9 AIV detecti on positive rate is as high as 23.36%,and the chicken group has the highest positive rate when the due date,at the same time the crowd bacteria separation rate also greatly improve,decrea sed immune resistance show that the period from the crowd,prone to avian influenza and the mixed infection of bacteria.In addition,serum samples of breeder chickens of different ages were collected to dynamically detect the antibody levels of avian influenza.At 3 days of age,t he maternal antibody levels of H5 and H7 were good.However,the antibody titer of H9 was h igh and the dispersion was large,which suggested that H9 subtype avian influenza infection might exist in the ancestral brood.At 21 days of age,the maternal antibody levels of all three subtypes of avian influenza decreased rapidly.But at this time,the dispersion of H9 antibody further increases,and some antibody levels are too high,which may be at risk of infection or have already been infected.At 63 days of age and 120 days of age,the antibody titer and pass rate of H5 and H7 increased,and the dispersion remained within the normal range.The antibo dy titer and pass rate of H9 increased,but the dispersion was still too high,and the antibody ti ter of some serum exceeded 12.At this time,the infection of subtype H9 avian influenza migh t occur in chickens.At 180 days of age and 240 days of age,the antibody levels of H5 and H7 were better and the pass rate was above 95%.At this time,although the dispersion of H9 anti body decreased,it did not reach the normal range.The results of antibody detection showed th at the H9 AIV antibody level of the chickens was unstable with large dispersion,and there wa s serious infection in the early stage,especially in brood and the expected date of delivery,but it was relatively stable in the late stage.According to the epidemiological investigation and the evaluation of the immune effect,t he comprehensive prevention and control measures of the poultry farm were reformulated,the vaccines were changed,and the immunization procedures were adjusted and optimized.Since then,the results of pathogen and antibody detection showed that there was no bird flu positiv e chicken in each period.At the same time,the antibody level of chickens was stable,the anti body titer basically remained in the normal range,the antibody dispersion decreased,and the pass rate increased greatly.It shows that the resistance of chickens to avian influenza is enhan ced,which can avoid the invasion of avian influenza virus and reduce the pressure of preventi on and control of other diseases.