RCR精选:餐桌上的牛肉哪种更环保?

春节期间，无论是走亲还是访友，餐桌上总少不了牛肉这一美食。牛肉的生产过程是否会对环境产生影响？各个阶段的环境影响有何区别？采取怎样的措施来减少对环境的影响？本文以墨西哥韦拉克鲁斯地区的牛肉生产过程为例，分析了两种不同的牛肉生产系统对环境的影响。在这两种牛肉生产系统中，一种是基于圈养的牛肉生产，即犊牛在大型屠宰场被宰杀后，运往超市售卖；另一种是基于散养的牛肉生产，即犊牛在屠户的家中被宰杀后，然后卖给附近的居民。

图片来源:http://thebodydietetics.com.au/blog/2014/4/28/grain-vs-grass-fed-what-type-of-meat-should-we-be-eating

1. 从生命周期角度系统地分析了整个牛肉生产过程的环境影响；

2.与基于圈养的牛肉生产系统相比，基于散养的牛肉生产系统在9类环境影响中具有较好的环境性能；

3.提高喂养饲料的质量可以提高牛肉生产系统的环境性能；

4.减少基于散养的牛肉生产系统中的电力消耗可以减少对环境的影响。

本文首先对两种牛肉生产系统（即基于圈养和基于散养的牛肉生产系统）的边界进行了界定。基于圈养的牛肉生产系统包括母牛产生犊牛、犊牛培育（散养）、犊牛育肥前准备（圈养）、犊牛育肥（圈养）、、运输、销售（大型超市）；基于散养的牛肉生产系统包括母牛产生犊牛、犊牛培育（散养）、犊牛育肥前准备（散养）、育肥（散养）、、运输、销售（小摊）。然后，根据牧场、屠宰场、零售场所等提供的统计数据以及一些专家的采访为基础建立生命周期清单分析。以1千克去骨头、去脂肪的牛肉产品为研究对象，利用SimaPro软件对整个牛肉生产过程的产业链的环境影响进行了分析。结果表明，在整个供应链中，犊牛培育过程对环境影响最大，育肥过程和屠宰过程次之，销售过程最小。相对而言，基于散养的牛肉生产系统对环境的影响小于基于圈养的牛肉生产系统。由于犊牛培育过程是整个供应链中对环境影响最大的一个部分，可以采取以下两种措施减少对环境的影响：增强犊牛培育过程母牛的繁殖能力和提高喂养饲料的质量。

两种生产系统不同阶段的环境影响如下图所示，对于犊牛培育过程，基于散养的牛肉生产系统的耕地占用影响较小，其它11种环境影响贡献较大，然而基于圈养的牛肉生产系统主要对气候变化、土壤酸化、水体富营养化贡献较大。对于育肥过程，基于圈养的牛肉生产系统的对人体毒性、水消耗、陆地生态毒性、化石燃料消耗、光化学臭氧合成、新鲜水和海水生态毒性贡献较大；屠宰过程，基于圈养的牛肉生产系统的环境影响主要有化石燃料消耗、光化学臭氧合成。与其他过程相比，两种牛肉生产系统的销售过程产生环境影响较小。

图2  基于圈养的牛肉生产系统（IS）和基于散养的牛肉生产系统（ES）

（CC:气候变化；HT:人体毒性；TA:土壤酸化；FEU:新鲜水富营养化；MEU：海水富营养化；TE: 陆地生态毒性; ALO：耕地占用；WD:水消耗；FD:化石燃料消耗；POF: 光化学臭氧合成; FE：新鲜水生态毒性；ME:海水生态毒性）

原文信息

Title: Environmental impact of beef production in Mexico through life cycle assessment

Authors: Adriana Rivera Huerta (a), Leonor Patricia Güereca(b), María de la Salud Rubio Lozano (a)

Affiliation:

a Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Av. Universidad 3000, Coyoacán, Ciudad Universitaria, 04510, Mexico City, Mexico

b Instituto de Ingeniería, Universidad Nacional Autónoma de México, Coyoacán, Ciudad Universitaria, 04510, Mexico City, Mexico

Abstract

Intensive and extensive systems of beef production in the Mexican tropics were analyzed. The aim of the study was to estimate and compare the environmental impact of two typical beef production systems in Veracruz, Mexico. A system boundary was established from farm production to prior to transport for consumer consumption, including intermediate stages of product processing, marketing and transportation. The functional unit was 1 kg of boneless and fatless beef. The life cycle inventory was built using information from case studies; farmers, slaughterhouses and retail point managers who provided information from records and expert knowledge were interviewed. The study included cow-calf processes, pre-fattening, fattening, processing and retail. Several impact categories were analyzed using SimaPro software and the ReCiPe Midpoint method for impact characterization. The results showed that for the extensive system, the cow-calf stage is the major contributor in eleven of the twelve impact categories analyzed, while in the intensive system, it is the main contributor to the climate change, terrestrial acidification, freshwater and marine eutrophication. The fattening stage of intensive system, has a predominant impact on human toxicity, water depletion, terrestrial ecotoxicity, fossil depletion, photo-oxidants formation, freshwater ecotoxicity and marine ecotoxicity; the processing stage has relevant contributions to fossil fuel depletion and the formation of photochemical oxidants in intensive systems. Finally, the marketing stage did not have a predominant impact on any category. The results indicated that the extensive system has better environmental performance than the intensive system for nine of the twelve studied categories. According last, it is important to improve the reproductive performance in calf breeding herds to mitigate emissions in the beef production chain as well as to improve livestock food quality in the extensive system for the mitigation of GHG emissions due to enteric fermentation.

本期编辑

李智伟，金山大学化工与冶金学院化学工程博士研究生，研究方向为化工过程节水节能研究。

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