| In recent years,with the rapid development of the layer farming industry,the scale of layer farms has become larger,and the breeding density has continued to increase,and the breeding cycle has also been extended.The pressure on disease prevention and control has continued to increase,especially for a variety of serotype poultry Influenza,Newcastle disease(ND),infectious bronchitis(IB),infectious laryngotracheitis(ILT),pericardial effusion syndrome(FAdV)and other new and old viral infectious diseases are widespread in laying hen farms.It is particularly important to establish scientific and reasonable immunization procedures for large-scale laying hen farms.The establishment of scientific and reasonable immune procedures is mainly based on the epidemiological investigation of related diseases and the evaluation of immune effects,on which the immune procedures are adjusted and optimized.In this study,serological,pathological and pathogenic detection methods were used to infect viral infections such as avian influenza,Newcastle disease,infectious bronchitis,infectious laryngotracheitis,and pericardial effusion syndrome in Tai’an and Surrounding areas of large-scale egg farms.The prevalence of the disease was investigated and analyzed.The survey results show that the prevention and control of the above diseases in Tai’an and surrounding areas of large-scale egg farms are good,but H9 subtype avian influenza,ND,IB,ILT,FAdV and other infectious diseases still have a higher incidence,and some chicken farms have caused greater economic losses.Combined with the morbidity characteristics of the flock,clinical necropsy,and histopathological examination,and using PCR or RT-PCR methods for detection,the positive detection rate of common viral diseases was counted.The results showed that among the suspected clinical cases,the detection rate of FAdV was the highest,the positive rate was 86.60%(84/97),followed by ILTV and IBV,the positive rates were 55.56%(15/27)and 48.28%(14/29),respectively.There were many suspected cases of low pathogenicity avian influenza and atypical Newcastle disease,and obvious characteristic lesions are also common in necropsy of sick chickens,but the detection rate of nucleic acid is low.The positive rate of H9N2 subtype AIV is 19.72%(19/106),and the positive rate of NDV is 10.59%(9/85).In 2018-2019,serum collected from large-scale egg farms in part of Tai’an and surrounding areas was tested for avian influenza(H5,H7,H9)and Newcastle disease antibody levels,and the antibody qualification rate was statistically analyzed.The results showed that the antibody levels of some chicken farms were low or too high in dispersion,which may lead to H9 AIV and NDV wild virus infection,leading to a high risk of disease.The reason is mainly related to the unreasonable immunization procedure or the improper selection of vaccine and the lack of scientific evaluation of immune effect.The qualified rate of antibodies against avian influenza and Newcastle disease detected in 2018-2019 was calculated on a quarterly basis.The results showed that the qualified rate of antibodies against avian influenza and Newcastle disease was slightly different in different quarters.Among them,the lowest pass rates of H5 and H7 antibodies in the second quarter were 92.57% and 87.32%,respectively,and the highest pass rates in the fourth quarter were 98.42% and 95.02%,respectively.The lowest pass rate of H9 antibody in the second quarter was 82.49%,and the highest pass rate in the first quarter was 94.11%.The lowest qualified rate of ND antibody in the third quarter was 89.67%,and the highest qualified rate in the first quarter was 94.64%.Overall analysis shows that the qualified rate of avian influenza antibody is from high to low: > in the first quarter,> in the fourth quarter,> in the third quarter,> in the second quarter.The qualified rate of Newcastle disease antibody was from high to low: > in the first quarter,> in the second quarter,> in the fourth quarter,> in the third quarter.Based on epidemiological investigation and the result of antibody detection,taking a large-scale DanJiChang Tai’an City as proving ground,according to the organiser breeding situation of avian influenza and Newcastle disease immune program adjusted optimization,immune effect evaluation methods for the detection and biological safety prevention and control measures,tracking test show that the immune program after adjustment,not another infectious bronchitis,infectious laryngotracheitis suspected cases,pericardial effusion,syndrome;Avian influenza,Newcastle disease immune effect is improved obviously,did not see H9 subtype of avian influenza and the occurrence of a typical Newcastle disease,H7 qualified rate increased to 100% from 80% before the adjustment,H9 qualified rate increased to 93.33% from 66.67% before the adjustment,all antibody levels of discrete degree is obviously decrease at the same time,the antibody level of qualified rate,increased protection,the crowd of herd immunity enhancement,effectively solve the main virus disease risk,has certain model promotion value.This study further enriched the epidemiological investigation data of large-scale egg farms in Tai’an and surrounding areas,and preliminarily found out the immunization status of avian influenza and Newcastle disease vaccines in large-scale egg farms.The adjustment and optimization of immunization procedures and the detection and evaluation methods of the immune effect will contribute to the effective prevention and control of infectious diseases in egg farms. |
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