In organic pig husbandry, the use of roughage is mandatory as dietary supplement. This study investigated the effects of oat silage on the fatty acid composition, in entire males and gilts, as well as indole and skatole levels in perirenal adipose tissue of entire males. Entire males and gilts (forty-five to forty-eight pigs/sex) were assigned to two dietary roughage feeds (control with straw vs. oat silage). There was no significant effect of silage or sex on total SFA and MUFA in pork fat. However, the oat silage increased the total PUFA n-3 and decreased the PUFA n-6/n-3 ratio. The content of boar taint compounds (skatole and indole) in the entire male pigs did not differ between diets, although human nose scoring rejected in a greater extent more pork fat from entire males supplemented with oat silage, compared with those only supplied with straw. Approximately 50% of the entire males (90 to 97 kg of carcass) had low skatole values (≤0.1 μg/g), that were below the range of boar taint detection, regardless of the feeding regime. This finding indicates that more studies should be performed to avoid the problem of taint detection in entire males under organic production.