Carbohydrates are sources of energy in swine diets, but not all types of plant carbohydrates are able to be utilized by the pig. Plant carbohydrates are classified in storage carbohydrates (starch) and structural carbohydrates (non-starch polysaccharides). Starch is the main source of energy in swine diets and digestion in the upper gut produces glucose. Non-starch polysaccharides are the main structural carbohydrates of plant cell walls that resist digestion in the upper gut and are subject to fermentation by gut microflora in the hindgut to produce volatile fatty acids. All carbohydrates that resist digestion in the upper gut of pigs are defined as fiber (Kerr and Shurson, 2013).