Comparative life cycle assessment of dietary supplementation with protected organic acid and essential oils in swine production

Previous studies have shown that supplementing pig diets with protected organic acids and essential oils (P(OA + EO)) improves intestinal health and performance across life stages. Building on trials conducted on commercial farms and in research institutions between 2007 and 2024, this study evaluated the environmental impact of pigs fed basal diets versus basal diets supplemented with 0.5-2 kg P(OA + EO)/ton of complete feed. The primary objective was extended to evaluate the additional effect of protease supplementation. The assessment followed the Livestock Environmental Assessment Performance guidelines for feed additives and pig supply chains and the International Organization for Standardization 14040/44 protocol. Using the OpenLCA v2.5 modeling environment, five impact categories, namely, greenhouse gas emissions (GHGEs), eutrophication, acidification, fossil resource demand, and water consumption, were analyzed via the ReCiPe 2016 midpoint (hierarchist) method. Supplementing sows with P(OA + EO) improved reproductive performance, increased litter size and reduced sow culling, which lowered the environmental impact by 8.6% per kg live weight (LW) in weaned piglets. In nursery pigs, an improved feed conversion ratio reduced farm emission intensities, resulting in a 7.4% reduction in the environmental impact per kg LW-nursed piglet. These improvements at the farrowing and nursery stages, combined with improved feed conversion in the grow-to-finish unit, contributed to an average environmental impact reduction of 4.5% per kg of LW grow-to-finish pig. Furthermore, integrating P(OA + EO) with an exogenous protease in nutrient-reduced diets resulted in an additional 8.4-12.7% reduction in GHGEs per kg LW pig compared with the non-supplemented group. Protease supplementation improved protein digestion, reducing the reliance on high-impact ingredients such as soybean meal and oil, whereas P(OA + EO) supported gut health and production responses. Together, these additives increase efficiency and contribute to more sustainable pig production.