| With the farm technology development and increasing demand on chicken,the broiler industry in China has developed fast and been the second largest livestock sector following swine industry.However,128 cases of high pathogenic avian influenza(HPAI)outbroke in China from 2004 to 2015,96 cases of which happened in the chicken flocks.HPAI has rebounded since 2011 and challenged the overall immunization strategy.The broiler has been the most susceptible poultry and suffered from the largest number of illness and mortality.HPAI impact on chicken meat supply and demand,the behavior of broiler farmers' biosecurity management in top broilers production provinces and control strategies optimization in Guangdong province were studied for sustainable development of broiler industry and public health in China.The partial equilibrium model of chicken meat supply and demand was established in the basis of the partial equilibrium theory and HPAI cases in chicken flock per year were introduced as influence parameters to the equation of chicken meat production,consumption per capita,imports and exports.Losses caused by HPAI were measured by equilibrium relationship and then it was found that there were 6193.9 thousand tons of chicken losses caused by HPAI from 2004 to 2013.Total chicken meat consumption were the largest and the next were imports,production and exports;chicken meat production,consumption per capita,imports and exports declined by 0.003%,0.006%,0.02% and 0.017% in the event of one case of HPAI outbreak.Seven disease prevention systems and eight disease prevention facilities regulated by conditions for animal epidemic prevention review in China were regarded as the evaluation framework on farmers' standard biosecurity management behavior in top broilers production provinces.Using valid 331 broiler farmers stratified sampling from Hebei,Jilin,Shangdong,Guangxi,Hubei and Guangdong province in China,Bivariate-Probit model was adopted to investigate determinants of farmers' adoption of disease prevention systems,disease prevention facilities first and then and Ordered Probit model were used to study farmers' overall disease prevention behavior.It was found that almost farmers implemented nonstandard biosecurity management and only 3.63% of farmers built overall disease prevention systems and disease prevention facilities.The three largest influence factors were studied that whether farmers were production organization membership,district and epidemic prevention regulations perception determined farmers' behavior of building overall disease prevention systems;district,epidemic prevention regulations perception and farming density were the determinants of farmers' establishing overall disease prevention facilities;whether farmers had enterprise contract,epidemic prevention regulations perception and broiler daily weight gain influenced farmers' overall disease prevention behavior.The North American Animal Disease Spread Model(NAADSM)was adopted to model HPAI control effect and direct control cost among broiler,layer,duck and goose flocks in Guangdong province in the basis of non-immunization policy and overall immunization policy respectively.In terms of control effect,overall immunization policy tended to reduce larger numbers of disease outbreak,culled poultries and culled farms than overall non-immunization policy.In terms of control cost,overall immunization policy suffered from much higher vaccine cost,whose final total cost was further more than the other policy.It was found through sensitivity analysis that with the disease report efficiency increase,the overall immunization policy could decrease illness rate and culling rate of poultries and shorten the time of first disease detection and the epidemics duration further.With the culling radius decrease,the overall immunization policy could reduce the culling rate of poultries and curb the spread of the epidemic effectively.The overall immunization policy had better be continued and improved based on national conditions and long term interest. |
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