Research On Optimizing The Structure Of Animal Husbandry In Beijing Under The Dual Constraints Of Environment And Emergency Support

With the rapid development of Beijing’s economy and the gradual formation of a large circulation and market pattern,livestock products have shifted from a seller’s market to a buyer’s market.The modernization of Beijing’s conventional livestock industry,which is mainly resourceand labour-intensive,has basically reached its quantitative limit,while many contradictions and problems have emerged that seriously restrict the construction of a clean,beautiful and ecologically sound first-class international metropolis in Beijing.In order to protect the environment,Beijing has been guiding livestock and poultry farming out of the prohibited areas gradually by decongesting the total amount of livestock and poultry farming,with a focus on the city’s serious groundwater over-exploitation areas and important water conservation areas,and the gradual withdrawal of retail households that do not comply with the relevant development plans.However,while guiding livestock and poultry farming out of the prohibited areas,it is also necessary to ensure the daily needs of local residents in Beijing for livestock products and to meet the supply of local residents in the event of emergencies.Based on the environmental carrying capacity theory,demand guarantee theory and comparative advantage theory of livestock development,this paper conducts a comparative study at the level of environmental assessment,demand guarantee dependable resources and regional comparative advantage to maximise the comprehensive factors such as resource endowment,economy of scale and technical efficiency of each region in Beijing.Firstly,the current situation of the three major livestock and poultry industries in Beijing was sorted out and summarised.On this basis,the current demand for crop manure nutrients and supply of livestock manure nutrients are calculated using the equilibrium method of breeding and feeding to arrive at the theoretical maximum livestock and poultry farming quantity,and then,based on the current farming quantity,the extent to which there is room for expansion in Beijing.The next step is to use a system dynamics model to analyse the various factors affecting the emergency security capacity of Beijing’s livestock industry,and to investigate how changes in factors such as yields,environmental carrying capacity and policy subsidies further affect the self-sufficiency rate of livestock products,thereby reflecting the changes in the size of Beijing’s emergency security capacity.Subsequently,a multivariate linear programming model is used to set constraints with the objective of maximising the inputs and outputs of Beijing’s livestock industry,and to derive an optimal industrial structure that will provide a basis for future industrial adjustments in Beijing’s livestock industry.The main findings of this study are as follows: at present,the total theoretical livestock carrying capacity of the city is 5.114 million pig equivalent,and the actual number of pigs kept is 1.589 million pig equivalent,which does not exceed the upper limit of the environmental carrying capacity of livestock and poultry breeding,and there is still room for 2.21 times more breeding.To further improve the emergency security capacity of livestock products in Beijing,attention should be paid to the cultivation of good breeds of livestock,the improvement of livestock production technology,the strengthening of the integration of breeding and farming,and the enhancement of government support in the process of livestock production.Through the comparative advantage analysis,it was found that there are six regions with comprehensive comparative advantage for live pigs,five regions with comprehensive advantage for dairy cattle and six regions with comprehensive advantage for poultry,and all of these regions have advantages.Further,through multi-objective optimisation,it was found that the number of pigs remained basically the same,the number of poultry farmed was reduced and the number of dairy cattle farmed was increased,so as to maximise the input and output.