Crude and acid oils from olive pomace as alternative fat sources in growing-finishing pigs

The inclusion of crude and acid oils from olive pomace can lead to more unsaturated meat products and, especially in the case of olive pomace acid oil, achieve a more economically and environmentally sustainable swine production. The objective of this trial was to study the effect of dietary supplementation with crude and acid oils from olive pomace, which are rich in monounsaturated fatty acids (FAs) and have differing free FA content, on growth performance, digestibility, carcass parameters and FA profile of Longissimus muscle (LM) and backfat in growing-finishing pigs compared to the conventional crude palm oil. A total of 224 male and female pigs [(Landrace × Large White) × Duroc] were randomly distributed into 48 pens according to initial BW (58.7 ± 9.71 kg, mean ± SD) and sex. Four experimental treatments were randomly assigned (n = 12 pens/treatment; 4–5 pigs/pen) for the growing (0–42 days) and finishing (40–62 days) phases. Treatments consisted of a basal diet supplemented with 5% (as-fed basis) palm oil (PO), olive pomace oil (O), olive pomace acid oil (OA) or a mixture (M) of PO and OA at 50/50. No differences were found in the growth performance results between PO, O or M, but animals fed OA showed a lower gain to feed ratio than M (P = 0.008). No differences were found in apparent ileal digestibility among treatments, however, animals fed O and OA showed the highest values of total FA apparent total tract digestibility, while those fed PO had the lowest values, and M had intermediate values (P < 0.001). No differences were observed in carcass composition among treatments. In relation to backfat and the LM FA profile, O and OA treatments led to a higher unsaturated FA to saturated FA ratio and a lower content in saturated FA than PO. Moreover, O showed a higher intramuscular fat (IMF) content in LM than PO (P = 0.037). It is concluded that olive pomace oil is an interesting alternative fat source that can be included at 5% in growing-finishing pig diets, leading to meat products with more IMF, rich in monounsaturated FA, reaching high FA digestibility values and good pig performance parameters. Alternatively, olive pomace acid oil blended with conventional palm oil did not negatively impact fat utilisation nor performance. Including these fat by-products reduced feeding costs and led to a more efficient and environmentally sustainable production.