An experiment was conducted to determine the best dietary fiber (DF) assay to estimate the effect of DF concentration on energy digestibility, and to predict the digestible (DE) and metabolizable (ME) energy of 9 corn co-products: conventional corn bran, corn bran with solubles, corn distillers dried grains with solubles (DDGS) conventionally produced, reduced oil DDGS, uncooked DDGS, high protein distillers dried grains, dehulled degermed corn, corn germ meal, and corn gluten meal. The apparent total tract digestibility (ATTD) of gross energy (GE), and the DE and ME of the 9 feed ingredients were determined in 20 growing pigs (BW = 25.9 ± 2.5 kg). Feed ingredients were analyzed for the concentration of dietary fiber: NDF, TDF, total non-starch polysaccharides (NSP), and 5 constituent monosaccharides of NSP, namely arabinose (Ara), xylose (Xyl), mannose (Man), glucose (Glc), and galactose (Gal). The concentration of xylose in NSP was the DF assay that best explained variation due to DF concentration in digestibility of energy, DE, and ME values, and can be used to predict the DE and ME values in corn co-products.