Both flaxseed and hay feeding increased levels of α-linolenic acid (LNA; 18:3n-3) in longissimus thoracis and backfat (P < 0.001). A forage type by flaxseed level interaction was observed for most LNA biohydrogenation intermediates (P < 0.05) that indicated feeding hay combined with flaxseed led to the greatest levels of total conjugated linolenic acid, total conjugated linoleic acid, total non-conjugated dienes and total trans-18:1.