奶牛是污染物产生较多畜禽，一头600 kg的成年奶牛，每天可产生30~50 kg粪便，废水0.4 m³，是同等条件下生猪、肉鸡和蛋鸡的数倍，已成为农业源污染的主要来源之一，随着奶牛养殖业开始向集约化、规模化和产业化转变，由此带来的环境负外部效应问题日益突出。环境规制是解决畜禽养殖过程中要素过度使用和环境污染外部性问题最直接有效的措施之一，但也是养殖场成本增加和结构调整的重要影响因素之一，当前环境规制与不同规模奶牛养殖效率以及技术进步的关系尚不清楚。该研究基于中国十个省份（自治区）2009—2019年不同规模牧场投入产出数据和环境规制政策规章文件数量，运用动态面板数据模型，研究了环境规制对奶牛养殖技术进步的影响特征与异质性，并考察了规模经营与环境规制的协同互补效应。结果表明，环境规制对奶牛养殖技术进步的影响呈“U”型特征，环境规制加速了养殖集约化发展、促进了资源的优化配置，形成了从污染治理带来的高成本、低技术进步逐步过渡到养殖结构优化产生的高收益、高创新投入的发展规律。不同规模牧场中，大规模和中规模全要素生产率高于小规模，环境规制对小规模牧场和大规模牧场技术进步具有正向促进作用，而对中规模牧场技术进步影响呈“U”型曲线，不同规模养殖的调节效应分析表明，中规模牧场奶牛存栏比重增加一定程度上缓解了环境规制初期给牧场带来技术进步下降的压力，但不能过度追求大规模养殖，大规模奶牛存栏比重增加带来更高的污染物处理成本迫使牧场减少对技术创新的投入，反而会削弱环境规制对奶牛养殖技术进步的促进作用。研究认为在推进适度规模养殖的基础上，在确保环境规制有效的情况下，要进一步加强环境规制，注重环境规制形式，使奶牛养殖技术尽快突破“U”型曲线拐点，为实现环境保护及经济增长“双赢”提供了理论支持。

Ensuring an acceptable level of edible agro-products quality and safety is necessary to provide adequate protection for consumers. It is the first time that we analyzed the edible agro-products quality and safety issues in the supply chain, including production, processing, circulation, and consumption. The results indicate that the agro-products quality and safety levels improves steadily, and the supervision system and standardization system are both enhanced significantly, however, certain challenges still remain in each stage of the supply chain and the entire supervision process. Finally, five recommendations regarding four aspects (production, processing, circulation, and consumption) are concluded.

This paper establishes a short-term prediction model of weekly retail prices for eggs based on chaotic neural network with the weekly retail prices of eggs from January 2008 to December 2012 in China. In the process of determining the structure of the chaotic neural network, the number of input layer nodes of the network is calculated by reconstructing phase space and computing its saturated embedding dimension, and then the number of hidden layer nodes is estimated by trial and error. Finally, this model is applied to predict the retail prices of eggs and compared with ARIMA. The result shows that the chaotic neural network has better nonlinear fitting ability and higher precision in the prediction of weekly retail price of eggs. The empirical result also shows that the chaotic neural network can be widely used in the field of short-term prediction of agricultural prices.

This paper studies how the price movements of pork, chicken and egg respond to those of related cost factors in short terms in Chinese market. We employ a linear quantile approach not only to explore potential data heteroscedasticity but also to generate confidence bands for the purpose of price stability study. We then evaluate our models by comparing the prediction intervals generated from the quantile regression models with in-sample and out-of-sample forecasts. Using monthly data from January 2000 to October 2010, we observed these findings: (i) the price changes of cost factors asymmetrically and unequally influence those of the livestock across different quantiles; (ii) the performance of our models is robust and consistent for both in-sample and out-of-sample forecasts; (iii) the confidence intervals generated from 0.05th and 0.95th quantile regression models are good methods to forecast livestock price fluctuation.

The paper studies the relationship, adjustment ability, path, efficiency and intensity of price transmission in the swine industry chain in China, which consists of the prices of corn, compound feed for fattening pig, piglet, pig and pork. Monthly prices covering a period of 18 yr (1994-2011) are analyzed using a Market-Chain Cooperated Model (MCM). The empirical results show that there exists a stable long-term cointegration and short-term dynamic relationship in the price system. First, the adjustment speed of each price series is very slow and the transmission path is top-down and one-way significantly. Second, the price from upstream to downstream lags about 2 mon, while there is no lag in price transmission from midstream to downstream. Third, in terms of price transmission intensity, the price of pig impacted greatly on pork price, not only in the current period but also through the whole period. Besides, the price of corn has the largest lagged effects on pork price. According to the above empirical results, we suggest that government should strengthen monitoring and early warning of the swine industry chain, especially the upstream and midstream, attach great importance to the timely adjustment of feed prices and perfect the measures of price subsidy.

This paper examines the vertical price relationship between upstream and downstream products in China’s layer industry chain by estimating elasticity coefficients of the price transmission. We use cointegration tests, error correction models and finite distributed lag models to analyze vertical price shifts between corn, layer feed, egg-laying chicken and egg prices. With monthly data from 1994 to 2010, our results show that various prices in China’s layer industry chain are well integrated. In addition, our results indicate that both long-run and short-run price relationships between upstream and downstream products in layer industry chain exist and the long-run equilibrium, to a certain extent, may eliminate the short-run dynamics price deviation. We also found that the influence of corn and feed prices on egg prices is still more remarkable than egg-laying chicken prices. Our findings imply that governments should pay more attention to corn and layer feed prices in order to stabilize egg prices under the conditions of market integration.