The environmental impact of dairy production: 1944 compared with 20071

TLDR

Pasture-based, low-input dairy systems of the 1940s are commonly perceived as more environmentally friendly than modern milk production systems. The study compares the environmental impact of modern (2007) US dairy production with historical practices exemplified by the 1944 US dairy system, aiming to guide efficient, low‑impact dairy management. A deterministic model of dairy herd metabolism and nutrient requirements, incorporating characteristic management practices, herd dynamics, and production data, estimated resource inputs and waste outputs per billion kilograms of milk for both modern and historical systems. Modern dairy production requires only 21 % of the animals, 23 % of the feed, 35 % of the water, and 10 % of the land, and generates 24 % of the manure, 43 % of the methane, 56 % of the nitrous oxide, and a 37 % lower carbon footprint per billion kilograms of milk compared to 1944 practices.

Abstract

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.