Accounting for uncertainty in the quantification of the environmental impacts of Canadian pig farming systems

The objective of the study was to develop a Life Cycle Assessment (LCA) for pig farming systems that would account for uncertainty and variability in input data and allow systematic environmental impact comparisons between production systems. The environmental impacts of commercial pig production for two regions in Canada (Eastern and Western) were compared using a cradle to farm gate LCA. These systems had important contrasting characteristics such as typical feed ingredients used, herd perfor-mance and expected emission factors from manure management. The study used detailed production data supplied by the industry and incorporated uncertainty/variation in all major aspects of the system including: life cycle inventory data for feed ingredients, animal performance, energy inputs and emis-sion factors. The impacts were defined using 5 metrics – Global Warming Potential, Acidification Po-tential, Eutrophication Potential (EP), Abiotic Resource Use and Non-renewable Energy Use, and were expressed per kg carcass weight at farm gate, EP was further separated into Marine (MEP) and Fresh-water (FEP). Uncertainties in the model inputs were separated into two types: uncertainty in the data used to describe the system (α uncertainties) and uncertainty in impact calculations or background data which affects all systems equally (β uncertainties). The impacts of pig production in the two regions were systematically compared based on the differences in the systems (α uncertainties). The method of ascribing uncertainty influenced the outcomes. In Eastern systems EP, MEP and FEP were lower (P