Tomato Processing By-Products as a Sustainable Source of Lycopene and Other Bioactive Compounds for Animal Nutrition: A Circular-Economy Perspective.

Tomato (Solanum lycopersicum L.) is the world's second-most cultivated vegetable. Production reached 192 million tonnes in 2023; approximately 23% is industrially processed, leaving 4.3 to 10.2 million tonnes of pomace each year. Despite its high content of lycopene, tocopherols, polyphenols, dietary fibre, and seed oil, most of this residue is composted, landfilled, or fed without prior processing. This narrative review examines how the chemistry of tomato by-products maps onto their effects in farm animals, and how green-extraction biorefinery fits within the European Green Deal. Reported pomace lycopene runs from 36.7 to 50.2 mg/100 g DM, with phenolics near 161.8 mg GAE/g. Lycopene is an efficient singlet-oxygen quencher; it activates Keap1-Nrf2-ARE signaling while dampening NF-κB. Supercritical CO2, ultrasound, microwave, pressurized-liquid, and NADES extractions can now recover up to 91% of peel lycopene using green, food-grade solvents. In broilers, 5 to 10% pomace or 30 to 400 mg/kg purified lycopene improves antioxidant status and lessens heat stress; in dairy ruminants, ensiled pomace at 10 to 40% maintains milk yield while improving milk PUFA. In finishing pigs and rabbits, dietary pomace or lycopene improves tissue oxidative stability, with growth benefits reported in heat-stressed rabbits. Standardized bioactive reporting and clearer inclusion limits remain the main research priorities.