From Waste to Sustainable Animal Feed: Incorporation of Olive Oil By-Products into the Diet of Bísaro Breed Pigs

The olive oil agro-industry generates large quantities of by-products, such as olive cake (OC), whose sustainable valorisation in animal feed can contribute to the principles of circular economy, waste reduction, and resource efficiency. This study evaluated the effects of incorporating OC into the diets of growing Bísaro pigs, focusing on productive parameters and the apparent total tract digestibility (ATTD). Two trials were carried out. In the first trial, 25 pigs were fed five diets containing 0, 5, 10, 15, and 20% exhausted OC (EOC) for 15 days. The results showed a linear decrease in ATTD with increasing EOC levels ( p < 0.001), but the increased feed intake compensated for the reduced digestibility, and growth performance was maintained. The initial and final live weight (LW), average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were not affected ( p > 0.05). In the second trial, 40 pigs were fed five diets for 82 days: a control diet and four diets incorporating 10% crude OC, 10% two-phase OC, 10% EOC, and 10% EOC with 1% olive oil. No significant differences were observed in final weight, ADG, ADFI, FCR, or the digestibility of DM, OM, CP, CF, and NDF. The results suggest incorporating moderate levels of OC into Bísaro pig diets could be a viable strategy for valorising by-products, reducing agro-industrial waste and increasing sustainability in animal production. In addition, the inclusion of OC had no negative impact on animal performance, highlighting the potential of OC as a sustainable ingredient for animal feed, which aligns with the objectives of the circular economy and sustainable livestock farming practices.