Department of Animal Sciences, Washington State University, Pullman, Washington 99164, USA.
J Anim Sci. 2011 Dec;89(12):4249-61. doi: 10.2527/jas.2010-3784. Epub 2011 Jul 29.
Consumers often perceive that the modern beef production system has an environmental impact far greater than that of historical systems, with improved efficiency being achieved at the expense of greenhouse gas emissions. The objective of this study was to compare the environmental impact of modern (2007) US beef production with production practices characteristic of the US beef system in 1977. A deterministic model based on the metabolism and nutrient requirements of the beef population was used to quantify resource inputs and waste outputs per billion kilograms of beef. Both the modern and historical production systems were modeled using characteristic management practices, population dynamics, and production data from US beef systems. Modern beef production requires considerably fewer resources than the equivalent system in 1977, with 69.9% of animals, 81.4% of feedstuffs, 87.9% of the water, and only 67.0% of the land required to produce 1 billion kg of beef. Waste outputs were similarly reduced, with modern beef systems producing 81.9% of the manure, 82.3% CH(4), and 88.0% N(2)O per billion kilograms of beef compared with production systems in 1977. The C footprint per billion kilograms of beef produced in 2007 was reduced by 16.3% compared with equivalent beef production in 1977. As the US population increases, it is crucial to continue the improvements in efficiency demonstrated over the past 30 yr to supply the market demand for safe, affordable beef while reducing resource use and mitigating environmental impact.
消费者通常认为，现代牛肉生产系统对环境的影响远远大于历史系统，其提高的效率是以温室气体排放为代价的。本研究的目的是比较现代（2007 年）美国牛肉生产与 1977 年美国牛肉系统生产实践的环境影响。基于牛肉种群的新陈代谢和营养需求，使用确定性模型来量化每十亿公斤牛肉的资源投入和废物产出。现代和历史生产系统都使用美国牛肉系统的典型管理实践、种群动态和生产数据进行建模。现代牛肉生产所需的资源比 1977 年的等效系统少得多，生产 10 亿公斤牛肉所需的动物数量为 69.9%，饲料数量为 81.4%，水数量为 87.9%，土地数量仅为 67.0%。废物产出也相应减少，现代牛肉系统每生产 10 亿公斤牛肉产生的粪便、CH4 和 N2O 分别为 81.9%、82.3%和 88.0%，而 1977 年的生产系统则为 81.9%、82.3%和 88.0%。与 1977 年同等牛肉生产相比，2007 年每生产 10 亿公斤牛肉的碳足迹减少了 16.3%。随着美国人口的增加，至关重要的是要继续提高过去 30 年来的效率，以供应市场对安全、负担得起的牛肉的需求，同时减少资源使用并减轻环境影响。
