The Role of Phytogenics in Pig Production and Their Proposed Association with the Circular Economy and Life Cycle Assessment: A Narrative Review and Conceptual Framework

Abstract

The intensification of global pig production has increased the pressure to reconcile productivity with animal health, food safety, and environmental sustainability. Phytogenic feed additives (PFAs)—plant-derived compounds including essential oils, oleoresins, phenolics, and polyphenol-rich extracts—have emerged as candidate alternatives to antibiotic growth promoters, with reported benefits of variable consistency for gut health, oxidative status, reproductive performance, and mycotoxin mitigation across the pig production cycle. In parallel, the pig sector is under increasing scrutiny for its environmental footprint, driving the adoption of circular economy (CE) principles and life cycle assessment (LCA) methodologies to quantify and reduce resource use and emissions. This narrative review synthesizes published evidence on the zootechnical, physiological, and health-related effects of phytogenics in swine, identified through literature searches of PubMed, Scopus, and Web of Science). It examines how their production, sourcing, and use intersect with circular economy strategies—particularly the valorization of agro-industrial by-products as phytogenic sources—and with the LCA-based evaluation of pig production systems. No specific study was identified through the search described that directly measured the environmental footprint of phytogenic feed additive use; the health/performance benefits of phytogenics and the environmental benefits of by-product substitution in pig diets are each independently well supported, but their combined net environmental effect remains unknown, and not all phytogenics originate from by-products; this review integrates the two bodies of evidence into a testable hypothesis—that phytogenics, via reduced morbidity/mortality and, where by-product-derived, circular sourcing, may contribute to a lower environmental footprint, rather than a demonstrated outcome. We regard phytogenics as a promising, mechanistically grounded candidate—rather than a confirmed lever—for reducing the environmental footprint of pig production and propose a concrete LCA methodology to test this hypothesis directly.