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This Article Free Via Open Access Full Text Full Text (PDF) All Versions of this Article: jas.2009-1781v1 87/6/2160    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Capper, J. L. Articles by Bauman, D. E. PubMed PubMed Citation Articles by Capper, J. L. Articles by Bauman, D. E.

The environmental impact of dairy production: 1944 compared with 2007¹

J. L. Capper^*, R. A. Cady and D. E. Bauman^*,2

^* Department of Animal Science, Cornell University, Ithaca, NY 14853; and Elanco Animal Health, Greenfield, IN 46140

² Corresponding author: deb6{at}cornell.edu

A common perception is that pasture-based, low-input dairy systems characteristic of the 1940s were more conducive to environmental stewardship than modern milk production systems. The objective of this study was to compare the environmental impact of modern (2007) US dairy production with historical production practices as exemplified by the US dairy system in 1944. A deterministic model based on the metabolism and nutrient requirements of the dairy herd was used to estimate resource inputs and waste outputs per billion kg of milk. Both the modern and historical production systems were modeled using characteristic management practices, herd population dynamics, and production data from US dairy farms. Modern dairy practices require considerably fewer resources than dairying in 1944 with 21% of animals, 23% of feedstuffs, 35% of the water, and only 10% of the land required to produce the same 1 billion kg of milk. Waste outputs were similarly reduced, with modern dairy systems producing 24% of the manure, 43% of CH₄, and 56% of N₂O per billion kg of milk compared with equivalent milk from historical dairying. The carbon footprint per billion kilograms of milk produced in 2007 was 37% of equivalent milk production in 1944. To fulfill the increasing requirements of the US population for dairy products, it is essential to adopt management practices and technologies that improve productive efficiency, allowing milk production to be increased while reducing resource use and mitigating environmental impact.

Key Words: carbon footprint • dairy • dilution of maintenance • environmental impact • greenhouse gas • productive efficiency