| Food security is an important foundation for social stability and economic development.Since the start of the reform and opening-up policy,China’s total grain output and per capita grain share have both achieved significant growth.However,with the upgrading of people’s food consumption structure,the trend of food consumption structure in China is changing with a steady decline in the demand for rations while a continuous expanding of the demand for feed grains.The food supply and demand situation is characterized by a contradiction between surplus rations and insufficient feed grains.At the same time,domestic food production is facing severe resource and environmental constraints,and foreign food supply is also increasingly strained by adverse factors such as geopolitical conflicts and extreme climate impacts.In the long run,China’s food supply and demand will remain in a tight balance,and the food security situation is not optimistic.In response to the problem of feed grain shortage,this dissertation comes up with two proposals,that expanding the source through increasing feed grain production capacity and moderate import,and reducing the cost by actively developing and utilizing established resources.Among them,Grain variety substitution is an effective way to reduce costs.This dissertation focuses on soybean and corn,which have prominent supply and demand contradictions in protein and energy feeds,and conducts a gradual analysis of "the basic laws of price fluctuations-the linkage between relative prices and alternative consumption-the measurement of unitary substitution relationships-the simulation of multiple substitution relationships",aiming to describe the impact of price fluctuations on feed grain variety substitution from different dimensions such as direction of impact,degree of impact,time of impact,and variety differences.The purpose of this dissertation is to propose key issues and challenges and provide ideas and methods for subsequent research.In addition to the introduction,concept definition,theoretical basis,and research status quo,the full text mainly discusses and draws relevant conclusions from the following five aspects:I.The transformation process of China’s food consumption structure is examined from the perspectives of residents’ food consumption and livestock and poultry breeding.Research shows that the transition in China’s per capita grain consumption structure occurred in 2014,while the total per capita grain consumption has also shifted from a slow decline to a rapid increase.From the perspective of total consumption(focusing on livestock and poultry breeding),the main use of grain consumption in China has been transformed from rations to feed grains in the mid and late 1990 s.Therefore,from the 1990 s to the early 21 st century,China’s food security has always been based on grain rations.II.Judging the main pressures and risks faced by feed grain supply security from various perspectives.Research shows that the structural contradiction between the supply and demand of feed grains in China currently coexists with the total contradiction.In terms of structural contradictions,the imbalance in the usage structure and the variety structure of feed grain consumption coexist.In terms of total contradiction,the supply and demand gap of China’s feed grain has almost linearly expanded since 2014,and by 2021,the gap has reached 126.612 million tons,of which soybean accounts for nearly 80%.III.A basic judgment on the characteristics of the feed consumption market is made for different varieties from the linkage between the prices of soybean,corn,and their main substitutes by variety and their feed consumption.With the improvement of the open-up level of China’s grain market,the transmission effect of foreign grain prices on domestic grain prices has increased,and the intensification of domestic grain price fluctuations has caused frequent changes in relative prices among different varieties.In details,the stability of the relative prices of most alternative varieties decreased from 2000 to 2021,and the specific performance varied with different varieties.In protein feed,the stability and sustainability of DDGS substitution have significantly decreased after the implementation of the "dual reaction" measures,while the substitution of other meal raw materials has always been unstable.In energy feed,the substitution behavior of wheat is relatively stable,followed by the stability of rice,and the stability of coarse grains is the most unstable.IV.A theoretical analysis framework is constructed for multiple substitution of feed and grain with Lagrange’s equation,which is the theoretical foundation for further analysis of the price impact mechanism of protein feed and energy feed variety substitution.We propose that feed enterprises in the feed grain consumption chain are the main actors in the substitution of feed grain consumption,and the profitability of feed enterprises is the endogenous driving force of the price impact mechanism.The relative prices between different varieties of the same type of feed grain(type refers to protein feed and energy feed)are the key factors determining the endogenous driving force.In addition to the endogenous drive generated by relative prices,rigid feed grain demand and scarce feed grain supply,technical factors,and policy factors are the exogenous drivers of feed grain substitution.In general,the feed grain multiple substitution system consists of four "elements",including two prerequisites(rigid feed grain demand and scarce feed grain supply),a core driving force(profit seeking nature of feed enterprises),and a key variable(feed grain price).V.The price impact mechanism of protein feed and energy feed substitution is examined from three levels:(1)examining the impact of the relative prices of different alternative varieties on their feed consumption by descriptive analysis;(2)quantifying the impact of the relative prices of different alternative varieties on their feeding consumption by empirical analysis;and(3)establishing a feed grain consumption system with GAMS models.Research shows that the basic relationship between consumption of alternative varieties and relative prices depends on the supply and demand pattern of each alternative variety.In varieties with relatively loose supply and demand balance,the relationship between relative prices and alternative consumption assumes a one-way causal relationship,while in varieties with tight supply and demand balance,the impact of relative prices is not obvious or even there is a reverse causal relationship.In addition,it is also pointed out that there are significant differences in the degree and timing of price impact among alternative varieties with one-way price effects.In addition to relative price changes,policy changes and foreign price transmission also affect the substitution behavior of internal varieties.In protein feed,DDGS feed consumption is affected by domestic soybean price changes and "double counter" measures.In energy feed,the minimum purchase price policy for wheat and rice not only stabilizes their own prices,but also indirectly affects the substitution of wheat and rice for corn.This article may have certain innovations in the following four aspects:I.The spatial state(periodic fluctuations and long-term trends)of relative price changes between soybean and corn and their substitutes from 1990 to 2020 is deconstructed using the H-P filter method.Based on the linkage between the relative prices of different spatial states and feed consumption,the stability and sustainability of the price impact substitution phenomenon are elaborated.II.We fully consider the differences in the supply and demand patterns of different varieties in the empirical analysis process.For varieties with endogenous problems in price variables,combining local equilibrium theory and cobweb model to explain the empirical results,forming a closed-loop analysis from theory to empirical analysis and then to theory.III.We examine the price impact mechanism in the multiple substitution of feed and grain based on the idea of system optimization,and expand the view rom a "one to one" relationship to a "one to many" relationship.The system analysis framework can not only examine the impact of price on multiple substitution,but also examine the impact of external market factors such as changes in feed grain supply capacity and feed grain demand on variety substitution.IV.The GAMS model was used to simulate the response of different varieties of consumption to price changes and constraint changes in protein feed and energy feed variety substitution systems,quantifying the impact of price on substitution behavior in multiple substitution.Possible shortcomings of this article:Firstly,the GAMS simulation results show that the optimal level of the system is difficult to be achieved in reality.Secondly,in the GMAS simulation process,the output corresponds to a set of static limit levels,which makes the simulation output fail to reflect the changes in feed consumption during the year as a result of real-time price fluctuations.In the future,as the data improves,this problem can be solved by using shorter data cycles such as monthly or quarterly data.Thirdly,currently,the constraints and objective functions set by the system are in linear form,but it is not ruled out that there is a non-linear situation under the influence of the law of diminishing marginal returns of factors or other objective factors.It is necessary to further combine relevant data and improve existing analytical methods to demonstrate. |
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