One farm with green oaks and another with cork oaks were chosen. Aiming to minimize weather effects and to provide swine equivalent pastures, under oak canopy, density of trees was similar and geographic area limited within Ourique County. Alentejano hogs, born and raised inside the region and recorded in the breed herd book, were fattened exclusively under oaks. Chemical composition of acorns from green oaks (AG) and from cork oaks (AC) were analysed including the fatty acids profile. Pigs were weighted 3 times during fattening period and ecographies were performed to evaluate back fat thickness (BF) and loin depth (LD). After slaughter samples of back fat were taken and analysed on chemical crude composition and fatty acids. Weight losses of hams were recorded along ripening period. Chemical composition of AG and AC were different. Considering percent of DM, we got for AG vs AC: NDF 24.9 vs 29.8 (p<0.001); CP 3.67 vs 5.57 (p<0.05); Lipids 8.00 vs 6.20 (p<0.05). Fatty acids profile have shown higher percentage of saturated on AG (p< 0.001) and exhibit higher percentage of unsaturated on AC (p<0.001). Acorns type, AG vs AC, didn’t affect significantly ADG neither the BF, but LD was deeper in hogs fattened with AC. Fatty acids of pigs fattened with AG vs pigs fattened with AC reflected the feed influence (C16:0, AG 19.53 vs AC 18.62 p<0.001; C18:0, AG 8.91 vs AC 8.43 p<0.05; C18:1, AG 56.09 vs AC 55.17 p<0.001; C18:2 AG
8.23 vs AC 10.42 p<0.001). Total hams losses during ripening period were not significant affected by feed intake
