The fat content of distillers grains with solubles (DGS) partially accounts for DGS feeding value being greater than corn. Finishing diets containing DGS to supply up to 8% of diet DM as fat may be fed without depressing cattle performance. However, feeding diets containing 8% diet fat with corn oil depresses cattle performance. The difference in rumen metabolism of these two fats is due to physical protection of DGS fat from interaction with rumen microbes. Due to an unknown mechanism, condensed corn distillers solubles, a liquid fat source, does not limit ruminal metabolism like corn oil. Optimum dietary fat level is dependent on the sources of fat in the diet