Environmental Impact of Finishing Pig Feeds with Reduced Crude Protein Content

Abstract The environmental impact of reduced crude protein (CP) feeds for finishing lean pigs (15–21 weeks and 70–120 kg live weight) based on six footprint attributes: phosphorus consumption, cumulative energy demand (non-renewable sources), climate change, acidification, eutrophication, and land competition, is evaluated based on lifecycle assessment (ECOALIM, version 9) under different soybean origin (regular or no deforestation risk) scenarios. To achieve a 2% reduction of CP content (14.3–12.2%) while maintaining dietary lysine (0.96%) and ideal protein supply, ingredient proportions were adjusted by increasing barley, wheat middlings, in-feed amino acids and mineral sources. Consequentially, some ingredients were decreased when reducing CP: soybean meal, wheat and sunflower meal. Maize and lard proportions were not modified across diets. Upon model application, low CP diet manufacturing led to increased phosphorus use, cumulative energy demand, climate change, acidification, and land competition and decreased eutrophication impact, compared with the standard feed. The overall trend results were steady when assuming a soybean meal source without deforestation risk, but eutrophication was more reduced and climate change impact increased when compared to standard feed. Although a previous in vivo trial showed that low CP diet reduces N load, it has little ability to mitigate carbon and phosphorus footprints in the Southern Europe scenario. Information © The Authors 2026