Life Cycle Assessment of Sustainable Broiler Production Systems: Effects of Low-Protein Diet and Litter Incineration

We conducted a life cycle assessment (LCA) to compare environmental impacts of conventional (CNV) broiler chicken production in Japan with those of three mitigation options: a low-protein diet supplemented with more crystalline amino acids (LP), incineration of broiler litter (IC), and their combination (LP + IC). Feed production, feed transport, broiler housing, and manure management were included in the LCA, with 1 kg of liveweight of broiler chicken as the functional unit. The CNV environmental impacts were: climate change, 1.86 kg CO₂e; acidification, 52.6 g SO₂e; eutrophication, 18.3 g PO₄e; energy consumption, 18.8 MJ. Since broiler manure management has a lower N₂O emission factor, the LP diet’s effects on greenhouse gas (GHG) emissions were limited. Because a large amount of ammonia is emitted from broiler-litter composting and the LP diet reduced nitrogen excretion and consequent NH₃ emission, the LP showed lower acidification and eutrophication potentials than CNV. The IC system reduced fuel consumption by utilizing the generated heat for broiler-house heating and thus had lower GHG emissions and energy consumption; it reduced ammonia emission from the manure-management process by incineration and thus had lower acidification and eutrophication potentials even when including NO_X generation by litter incineration. The LP + IC system had lower environmental impacts than CNV: for climate change (by 16%), acidification (48%), eutrophication (24%), and energy consumption (15%). Mitigation opportunities for broiler chickens remain, and broiler production systems with mitigation options help produce chickens more sustainably.