Comparing the environmental impacts of pasture-based and confinement-based dairy systems in Nova Scotia (Canada) using life cycle assessment

Abstract

A life cycle assessment (LCA) of dairy systems in Nova Scotia was conducted to compare environmental impacts of typical pasture and confinement operations. Data on material and energy inputs and outputs of these systems were obtained from local researchers and industry, and life cycle impacts in 11 categories were quantified. Use of concentrate feeds, N fertilizers, transport fuels and electricity were dominant contributors to environmental impacts. Somewhat surprisingly, grazing cows for five months per year (typical of pasture systems in Nova Scotia) had little effect on overall environmental impact. Scenario modelling suggests, however, that prolonged grazing is potentially beneficial. Compared with total confinement, a seven-month grazing scenario performed better in seven of the environmental impact categories evaluated with greatest potential improvements associated with acidification potential, ozone depletion potential, human toxicity and fresh water ecotoxicity. In contrast, land use was the only category in which an increased reliance on pasture is predicted to result in a marked increase in environmental impact.