Corn production in Western Canada has increased with development of short-season varieties partially offsetting the use of barley as a silage and grain source. The current study evaluated effects of silage and cereal-grain source on subcutaneous fat (SCF) composition of finishing cattle. Steers (465 ± 28.0 kg) were assigned to 24 pens (12 steers per pen) in a 2 × 3 factorial design for an 89 d finishing study. Diets contained corn silage or barley silage at 8% [dry matter (DM)] combined either dry-rolled barley grain (BG; 86% of DM), corn grain (CG; 85% of DM), or an equal blend of BG and CG (85% of DM). Bone-in ribeyes were collected from four steers per pen, and subcutaneous fatty acids were analyzed by gas chromatography. Feeding dry-rolled CG increased dietary fat and 18:2n-6 concentrations, resulting in small increases in 18:2n-6, total n-6 fatty acids, and n-6/n-3 ratios in SCF (P < 0.05). There were no changes in proportions of major trans-18:1 isomers (t10-18:1 or t11-18:1), the main natural isomer of conjugated linoleic acid (cis9,t11–18:2), or n-3 fatty acids. Substitution of dry-rolled CG for BG in finisher diets can, therefore, be done without substantially altering the fatty acid composition of beef fat, including polyunsaturated fatty acid biohydrogenation products.