Increasing feed costs and increasing grain processing have resulted in processing co-products commonly being used in swine feed. Adding co-products changes the nutritional profile of feed, and alters the starch and fibre content. Adding co-products does not necessarily effect average daily gain, feed intake or efficiency; however, fats and fibre content can have an impact on carcass characteristics. Oils in co-products can change the fat profile, and fibre can stimulate organ development – leading to lower carcass weight from the same slaughter weight. Using fibre-degrading enzymes can increase the digestibility of some co-products, but appears to have varied results depending on the specific co-product. Starch can make up a large content of feed, and its digestibility impacts whether it will be converted to glucose or fermented. In vitro and in vivo testing showed a linear relationship between the digestibility and glucose appearance. Fibre that is more fermentable will degrade faster, produce more gas, and metabolites that benefit gut health. Adding co-products to feed can reduce costs, and they can have large variety in starch and fibre properties.