Olive Mill Wastewater Bioactive Molecules: Applications in Animal Farming

For many years, olive by-products have been considered environmental pollutants because of their high organic content and phytotoxic activity. However, in the last decades, an increased interest in olive mill wastewater (OMWW) has been registered since the polyphenols contained in it have shown, in vitro and in vivo, antioxidant, anti-inflammatory, and antimicrobial activities. Both in farmed fish and terrestrial animals, oxidative stress induces pathological conditions, such as enteritis, peripheral and central infections, and cancer. The administration of OMWW seems capable to prevent these diseases or reduce their symptoms, promoting animals’ growth performance and health. Such beneficial effects have been observed in several food-producing animal species, such as lambs, pigs, chickens, and fishes, and are largely attributed to the contained polyphenols (mainly Hidrossityrosol, Tyrosol, Caffeic Acid, Oleuropein). In conclusion, being OMWW one of the most abundant agro-industrial by-products rich in toxic pollutants with disposal still exceedingly difficult, the recovery and valorization of OMWW is a priority for the implementation of a circular economy, although numerous efforts are still necessary to valorize this waste reducing its environmental impact.