The life cycle impacts of feed for modern grow-finish Northern Great Plains US swine production James J. Stone a,⇑ , Christopher R. Dollarhide b , Jennifer L. Benning a , C. Gregg Carlson c , David E. Clay d a Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA b Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA c Department of Animal and Range Sciences, South Dakota State University, Brookings, SD 57707, USA d Department of Plant Sciences, South Dakota State University, Brookings, SD 57007, USA article info Article history: Received 29 June 2011 Received in revised form 9 September 2011 Accepted 1 November 2011 Available online 29 November 2011 Keywords: Life cycle assessment Swine production DDGS Feed production abstract A life cycle assessment (LCA) model was developed to analyze the environmental impacts per head of swine for typical feed rations of Northern Great Plains (NGP) US grow-finish swine production. The all- inclusive ‘field to gate’ approach incorporated steps ranging from corn and soybean production to ship- ping the market weight pig to a slaughtering facility. Feed production scenarios included: (1) a standard feed diet of 72% corn and 28% soymeal using 100% synthetic fertilizer; (2) standard feed diet using 40% manure as fertilizer; (3) modified feed diet using dry distillers gains with solubles (DDGS), with 100% DDGS allocation towards ethanol production; and (4) modified feed diet with 50% DDGS allocation towards ethanol production. For the standard NGP feed diet, enteric emissions and feed production were the two largest contributors towards climate change impacts, while feed production further resulted in significant contributions towards human health damage (44.6%), ecosystem diversity (67.4%), and resource availability (75.0%). DDGS incorporation assuming 100% allocation reduced corn and soymeal inputs considerably, resulting in overall decrease in impacts associated with climate change (2.7%), ter- restrial acidification (7.1%), and both marine (14.6%) and freshwater eutrophication (22.7%); how- ever terrestrial ecotoxicity increased (+22.9%) due to natural gas drying. 50% DDGS allocation increased all impact categories, with the greatest change found for terrestrial ecotoxicity (48.4%). The study results highlight the significant LCA impact contributions associated with feed during grow-finish swine production, and the benefits associated with DDGS incorporation; however, LCA benefits were real- ized only if 100% DDGS allocation was applied towards ethanol production. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction On a global scale, pork production accounts for approximately 40% of the world’s meat production, with the US currently the sec- ond largest supplier of pork after China (FAO, 2011). Within the US, the largest share of pork production resides within the Midwest re- gion (48%), with the Southeast (15%) and Northern Great Plains (NGP) regions (13%) further contributing towards total US pork production (USDA, 2009b). The number of pork producers has steadily decreased since the 1960s, while the total annual head has remained relatively constant, signifying a shift from small, independent operations to larger, high throughput operations common of today’s modern facilities (Meyer, 2007; USDA, 2009a). These larger, more concentrated operations have placed in- creased demands on local feedstuff, water, energy, and manure handling processes. Recently, there has been a movement within the pork industry to quantify and minimize environmental impacts associated with pork production as part of sustainable agriculture efforts. One important aspect of this movement consists of review- ing the entire supply chain using life cycle assessment (LCA) mod- eling to ascertain environmental impacts associated with various stages of pork production. LCA modeling provides both industry and regulatory agencies a tool to identify and quantify ‘hot spots’ within the pork supply chain. Indeed, notable hot spots recently identified include environmental impacts associated with manure, building operations, and feed production for both US (Lammers et al., 2010a,b; Pelletier et al., 2010; Stone et al., 2010) and EU (Basset-Mens and van der Werf, 2005; Eriksson et al., 2005; Nunez and Fermoso, 2005; Stephen et al., 2009) swine productions operations. Further, several studies conclude that feed production generally accounts for the greatest life cycle-energy inputs during swine production, including as a significant contributor to greenhouse gas emissions (Eriksson et al., 2005; Lammers et al., 2010a; Stephen et al., 2009). As there are inherent differences between NGP swine opera- tions compared to those found in other regions of the US (Stone et al., 2010), similarly, there are also regional differences in feed 0308-521X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.agsy.2011.11.002 ⇑ Corresponding author. Tel.: +1 605 394 2443; fax: +1 605 394 5171. E-mail address: james.stone@sdsmt.edu (J.J. Stone). Agricultural Systems 106 (2012) 1–10 Contents lists available at SciVerse ScienceDirect Agricultural Systems journal homepage: www.elsevier.com/locate/agsy