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Five ruminally and duodenally fistulated, Holstein steers were used in a 5X5 Latin square metabolism experiment to evaluate digestibility of wet distillers grains plus solubles (WDGS) compared with corn fiber and corn oil in finishing diets. Treatments were a 40% WDGS diet, a composite of corn fiber and corn protein (COMP), COMP plus corn oil to equal the distillers diet (COMP+OIL), and dry-rolled corn control diets without (CON) or with corn oil (CON+OIL). Cattle fed WDGS had numerically lower rumen pH compared with cattle fed other treatments. Cattle fed the WDGS had greater propionate, lower acetate:propionate ratios, greater total tract fat digestion, and a greater proportion of unsaturated fatty acids reaching the duodenum than cattle fed other treatments. These data indicate the higher energy value of WDGS compared with corn is not due to acidosis control, but to more propionate production, higher fat digestibility, and more unsaturated fatty acids reaching the duodenum.