[ Objective] The paper was to understand the natural infection status of avian leukemia in some indigenous chicken breeds of China. [ Method ] Using ELISA assay and virus isolation method, epidemiological investigatio...[ Objective] The paper was to understand the natural infection status of avian leukemia in some indigenous chicken breeds of China. [ Method ] Using ELISA assay and virus isolation method, epidemiological investigation of ALV-AB and ALV-J avian leukemia of 10 indigenous chicken breeds were conducted. ALV dynamics were monitored in F2 generation of four chicken lines. ALV pollution of attenuated live vaccines used in raising process was also inspected through sampling method. [ Result] The positive rate of ALV-P27 antigen was 0 -62.1% ; the positive rate of ALV-AB antibody was 0 -25.0% ; the positive rate of ALV-J antibody was 0 - 59.0% ; the positive rate of virus isolation was 0 - 22.0%. The positive rate of ALV-P＇27 antigen in 1 -day-old chick mecunium of four lines was 6.0% - 67.0%. The positive rate of virus isolation in 6-week-old chickens was 2.0% - 34.3%. Two kinds of vaccines from two hatches pro- duced by a manufacturer were polluted by ALV. [ Conclusion] Most indigenous chickens were infected by ALV. There were great differences among different breeds of indigenous chicken, which might be related to ALV genetic resistance of different indigenous chickens. The ALV positive rates of F： chicks were slightly enhanced in some lines, which might be related to vaccine pollution.展开更多
This paper examines the U.S. meat demand impacts of the announced outbreaks of bovine spongiform encephalopathy（BSE） and avian influenza（AI）. Findings indicate that beef and chicken demand was negatively affected ...This paper examines the U.S. meat demand impacts of the announced outbreaks of bovine spongiform encephalopathy（BSE） and avian influenza（AI）. Findings indicate that beef and chicken demand was negatively affected by BSE and AI disease outbreaks. Specifically, in the short run, U.S. consumers shift demand due to both outbreaks but more so due to domestic disease outbreaks than for outbreaks occurring overseas-the impact of U.S. AI outbreaks is about 0.5% for beef and the impact of U.S. BSE cases is around –0.42% for beef and 0.4% for pork, respectively. Regarding the BSE shock on meat demand, there is a high rate of beef demand adjusted from disturbance to the long-run equilibrium and a lower adjustment rate for chicken demand because of the repeated outbreaks of AI worldwide. In the long run, information related to severe, persistently recurring overseas animal disease outbreaks changes U.S. consumers＇ meat consumption patterns. Although effects of animal diseases on U.S. meat demand were statistically significant, the magnitudes were small-the impact of WHO reported human death numbers for AI is 0.005% for beef, –0.002% for pork, and –0.006% for chicken and the impact of U.S. BSE cases is 1.1% for pork and –0.7% for chicken.展开更多
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201203055)Agricultural Three-new Engineering Project of Jiangsu Province(SXGC[2014]288)+1 种基金Natural Science Foundation of Jiangsu Province(20151317)Science and Technology Project of Yangzhou City(YZ2014144)
文摘[ Objective] The paper was to understand the natural infection status of avian leukemia in some indigenous chicken breeds of China. [ Method ] Using ELISA assay and virus isolation method, epidemiological investigation of ALV-AB and ALV-J avian leukemia of 10 indigenous chicken breeds were conducted. ALV dynamics were monitored in F2 generation of four chicken lines. ALV pollution of attenuated live vaccines used in raising process was also inspected through sampling method. [ Result] The positive rate of ALV-P27 antigen was 0 -62.1% ; the positive rate of ALV-AB antibody was 0 -25.0% ; the positive rate of ALV-J antibody was 0 - 59.0% ; the positive rate of virus isolation was 0 - 22.0%. The positive rate of ALV-P＇27 antigen in 1 -day-old chick mecunium of four lines was 6.0% - 67.0%. The positive rate of virus isolation in 6-week-old chickens was 2.0% - 34.3%. Two kinds of vaccines from two hatches pro- duced by a manufacturer were polluted by ALV. [ Conclusion] Most indigenous chickens were infected by ALV. There were great differences among different breeds of indigenous chicken, which might be related to ALV genetic resistance of different indigenous chickens. The ALV positive rates of F： chicks were slightly enhanced in some lines, which might be related to vaccine pollution.
文摘This paper examines the U.S. meat demand impacts of the announced outbreaks of bovine spongiform encephalopathy（BSE） and avian influenza（AI）. Findings indicate that beef and chicken demand was negatively affected by BSE and AI disease outbreaks. Specifically, in the short run, U.S. consumers shift demand due to both outbreaks but more so due to domestic disease outbreaks than for outbreaks occurring overseas-the impact of U.S. AI outbreaks is about 0.5% for beef and the impact of U.S. BSE cases is around –0.42% for beef and 0.4% for pork, respectively. Regarding the BSE shock on meat demand, there is a high rate of beef demand adjusted from disturbance to the long-run equilibrium and a lower adjustment rate for chicken demand because of the repeated outbreaks of AI worldwide. In the long run, information related to severe, persistently recurring overseas animal disease outbreaks changes U.S. consumers＇ meat consumption patterns. Although effects of animal diseases on U.S. meat demand were statistically significant, the magnitudes were small-the impact of WHO reported human death numbers for AI is 0.005% for beef, –0.002% for pork, and –0.006% for chicken and the impact of U.S. BSE cases is 1.1% for pork and –0.7% for chicken.
