Upcycling former food products in livestock diets: a one health approach to prevent resource-depleting farming systems

• Upcycling former food products up to 30 % in pig diets reduces land and water use on average by 21 %−26 %, promoting resource-efficient livestock systems. • Replacing conventional feed with former food products decreases feed imports, enhancing local resource availability and food system resilience. • An in vivo feeding trial confirms that former food products maintain pig growth performance, metabolism, and welfare, supporting sustainable animal production. The growing demand for animal-source foods (ASFs) intensified competition between the food and feed sectors, straining limited natural resources. Integrating One Health principles -acknowledging the interconnectedness of human, animal, and environmental health -can enhance sustainability in ASF production. This study evaluates the potential of former food products (FFPs), safe but non-marketable foodstuffs, to replace up to 30 % of conventional pig feed. Using data centered around 2018 for EU27 and US industrial pig systems, results show 11–42 % savings in land and water use, equivalent to 5.3Mha of land and 27.6 km³ of water annually. Reducing feed imports increases local resource availability and decreases reliance on virtual resources. An in vivo trial confirmed that FFP-based diets maintain pig growth performance, metabolism, and welfare. These findings underscore the environmental benefits of FFPs and their potential to align ASF production with circular economy and One Health principles, mitigating global sustainability challenges.