Environmental impacts of housing conditions and manure management in European pig production systems through a life cycle perspective: A case study in Denmark

Abstract The potential of modifications in the housing conditions and manure management to reduce the environmental impact of a European pig production system were evaluated. The study was carried out using a cradle-to-farm gate life cycle assessment (LCA), with a functional unit of 1 kg of live weight pig at farm gate. The study used Danish pig systems as a case in point, with data provided by the Danish Pig Research Centre (SEGES). Potential environmental impact hotspots at pig housing and manure management were identified through a local sensitivity analysis. A set of pig housing and manure management alternative scenarios were analysed using parallel Monte Carlo simulations, to quantify interactions between these two components of the system. The manure management scenarios were slurry acidification, screw-press slurry separation and centralised anaerobic digestion of slurry. The pig housing scenarios were constructed around variations of the following factors: i) level of barn insulation, ii) in-barn temperature, iii) ventilation efficiency, iv) level of slurry dilution and v) frequency of slurry removal from barn pits. Anaerobic digestion significantly reduced the environmental impact for Non-Renewable Resource Use (−34.1% compared to baseline), Non-Renewable Energy Use (−40.1%) and Global Warming Potential (−9.20%). Slurry acidification led to significant reductions in Acidification (−28.1%) and Eutrophication Potential (−14.2%). Slurry separation significantly reduced only Non-Renewable Energy Use (−2.26%). The scenario analysis showed that the environmental performance of all manure management alternatives was affected by variations in all housing related factors, except for in-barn temperature. The largest improvement in environmental performance of the manure management component was achieved for Acidification Potential (−5.51%) by increasing the level of slurry dilution under baseline manure management conditions. Slurry acidification was the least sensitive manure management alternative to modifications in pig housing. Both manure management and housing conditions have the potential to reduce the environmental impact of pig systems in Europe.