A Survey Of The Epidemiology And Prevention Of Chicken ND In Cage-free Hens In Miyun County

According to the study of Miyun County cage-free hens Newcastle disease epidemiologicalinvestigation and collection of suspected Newcastle disease onset cage-free hens, by usingbacteriological techniques and virus isolation and identification. The result is that23cage-free hensgroups were identified with Newcastle disease virus and the number of cage-free hens withGram-negative bacteria is higher than Gram-positive bacteria. We inoculate23suspected Newcastlediseases for the chick embryo allantoic cavity. Through the method of the Hemagglutination assay (HA)test and Hemagglutination inhibition (HI) assay on the suspected cage-free hens. We found the23suspected allantoic fluid samples have blood clotting and also can be inhibited by the standard positiveserum.According to the international judgment Methods for Newcastle disease virus: we measured theintracerebral pathogenicity index in day-old chicks (ICPI) and the mean death time of chick embryos(MDT for23suspected Newcastle Disease virus. The results were1.71-1.89;2.45-2.69. According tothe regulations of the international Newcastle disease virus of virulence decision criteria to determinethe test results, these isolated viruses are virulent Newcastle disease virus. Animal regression test is usedto detect these separate viruses, the incidence rate is100%and the vaccinated cage-free hens’ mortalitybetween70%-100%, meanwhile, the control group showed no abnormalities. The average Newcastledisease HI antibody titers of egg chicken group were surveyed. The results showed that the HI antibodytiters were less than26. Highly virulent Newcastle disease virus detection rates in these infectedcage-free hens groups were high.By the investigation of Miyun County cage-free hens Newcastle disease, it shows that the diseasecan occur throughout the year, but the higher frequency in spring and winter. In terms of stage ofdevelopment, it occurs more frequently in peak of egg-produce stage, and different feeding;immunization management can also influence the occurrence of Newcastle disease.Through the analyze of possible reasons which can cause the occurrence of Newcastle disease inMiyun county, the comprehensive control measures of this disease has been established. By testing thesample place which faced the virus before and conducting comprehensive prevention method to makethe rate dropped by88.8%, which significantly decreased the incidence of disease. Thus, acomprehensive prevention and control measures for the prevention and control of Newcastle disease isfeasible.