Environmental trade-offs of pig production systems under varied operational efficiencies

G.A Mcauliffe,T Takahashi,L Mogensen,J.E Hermansen,C.L Sage,D.V Chapman,M.R.F Lee

doi:10.1016/j.jclepro.2017.07.191

Abstract

Production of pork, the most consumed meat globally, is estimated to emit 668 m tonnes CO2-eq of greenhouse gases each year. Amongst various production systems that comprise the pig industry, grain-based intensive production is widely regarded as the largest polluter of the environment, and thus it is imperative to develop alternative systems that can provide the right balance between sustainability and food security. Using an original dataset from the Republic of Ireland, this paper examines the life-cycle environmental impacts of representative pig farms operating under varying production efficiencies. For the baseline farm with an average production efficiency, global warming potential (GWP), acidification potential (AP) and eutrophication potential (EP) per kg carcass weight departing the slaughterhouse were estimated to be 3.5 kg CO2-eq, 43.8 g SO2-eq and 32.1 g PO4-eq, respectively. For herds with a higher production efficiency, a 9% improvement in feed conversion ratio was met by 6%, 15% and 12% decreases in GWP, EP, AP, respectively. Scenario and sensitivity analyses also revealed that (a) a switch to high-protein diets results in lower GWP and higher AP and EP, and (b) reducing transportation distances by sourcing domestically produced wheat and barley does not lower environmental impacts in any notable manner. To improve cross-study comparability of these findings, results based on an auxiliary functional unit, kg liveweight departing the farm gate, are also reported.

Highlights

Agricultural production is one of the key anthropogenic activities where environmental burdens can potentially be reduced
Using the life cycle assessment (LCA) framework, which has been applied to a diverse range of pig production systems as reviewed by McAuliffe et al (2016), the present study investigates the environmental performances of intensive pig production systems in the Republic of Ireland (RoI) under different production efficiencies
CH4 emissions from manure management and enteric fermentation respectively generated 23% and 5% of total global warming potential (GWP), closely following the results reported by MacLeod et al (2013)

Summary

Introduction

Agricultural production is one of the key anthropogenic activities where environmental burdens can potentially be reduced. The farming sector occupies 30% of the Earth's terrestrial surface (Steinfeld, 2006) and 75% of this land use is associated with livestock production (Cassidy et al, 2013). Changing diets and population growth have been associated with 65% of land use change between 1961 and 2011 (Alexander et al, 2015), and demand for livestock products will continue to exceed expected population growth (34%) at least until 2030 because of the ongoing dietary shifts in developing countries (Havlík et al, 2014). Higher feed conversion efficiency (FCE) has been shown to reduce the environmental impact per pig unit, as emissions and losses associated with the feed production stage become smaller (Nguyen et al, 2011). Published research investigating these effects on the system-wide footprint is rather limited, and the environmental benefit of economically improved pig operations is not clearly understood

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