The digestibility of fiber is greater in distillers dried grains with solubles (DDGS) than in corn, indicating that fiber digestibility is improved by processing or fermentation at the ethanol plant. Our results indicated, however, that because of its components, fiber in corn co-products is more resistant to microbial fermentation. The digestibility of dietary fiber is also variable among corn co-products, which in turn may affect the digestibility of energy and nutrients differently. Results also indicated that increasing the fiber level in the diet with corn fiber, as may be the case of DDGS, decrease the digestibility of energy, fiber and nutrients of the diet, including lysine and most of the AA. Fat proved to be a mechanism to compensate for the reduction in energy supply when fiber is increased. The relatively high content of fat in DDGS mitigates the negative effects of increased fiber in the diet due to DDGS inclusion. Production of lower fat varieties of DDGS, however, may decrease the digestibility of energy and nutrients in the diet even further and as a consequence, the dietary net energy. It is also important to consider that about half of the fiber from corn co-products escapes fermentation in the digestive tract of the pig. Industrial processes leading to the improvement of fiber digestibility of corn co-products are a good alternative to better utilize the energy trapped in the fiber matrix.