A Survery Of Epidemiologic And Prevention Of Chicken Infectious Bursal Diseas In Weifang District Of Shandong Province

According to the epidemic situation of chicken IBD in Weifang district of Shandong province , in this study, the epidemiologic characteristic of IBD in this area was investigated in several aspects, prevention and cure measures were also explored and applied in practice for controlling the disease more effectively.1.Epidemiologic investigation of chicken Infectious Bursal Disease in Weifang district of Shandong provinceThe result of epidemiologic investigation of IBD in Weifang district of Shandong province shows that the disease usually takes place in summer and fall, but there is a trend of happening in the whole year; it is most popular in 3-6 week-old chickens, but presenting a both-pole developing trend; there is no typical symptoms and pathologic changes; the average incidence of disease in ill chicken flock is 69.6%, and the average mortality is 11.3%. The factor of management and immunity plays an important role in the prevention of IBD.2.The pathogenicity of IBDV strain isolated from affected chicks in Weifang district of Shandong provinveThe research of the pathogenicity of IBDV strain isolated from affected chickens in Weifang district of Shandong province was conducted ,compared with the standard strain of BC6-85, the findings shows that the pathogenicity of these isolated strains belongs to three levels: the first type is the strains holding a pathogenicity similar to the BC6-85 standard strain, such as CL-1, CL-3, GM-2 etc, with an ELD₅₀ between 10^-4.25/0.1ml and 10^-5.375 /0.1ml, and a mortality of 20%³0%; the second type is the strains whose virulence is stronger than the BC6-85 standard strain, such as the strain of LQ-1, CL-2, AQ-3 etc, and their ELD₅₀ is between 10^-6.25 /0.1ml and 10^-6.875 /0.1ml, and the mortality of chickling is between 52.5% and 70%; the third type is the strains whose virulence is lower than BC6-85, such as QZ, AQ-1, ZC-3 etc, with an ELD50 between 10^-2.0 /0.1ml and 10^-2.875/0.1ml and a mortality of chickling between 2.5% and 7.5%. 3.The protection test of the vaccine of IBDCertain chicken flocks were immunized respectively with different vaccines of...