As mentioned earlier, the nonfermentable solids in distilled mash (stillage) contain variable amounts of fiber and protein, depending on the feedstock. The liquid also contains soluble protein and other nutrients and as such remains valuable. The recovery of the protein and other nutrients in stillage for use as livestock feed can be essential to the overall profitability of etha­nol fuel production. Protein content in stillage varies with feedstock. Some grains such as corn and barley yield solid by-products that are called dried distillers grains (DDGs). Protein content in DDG typically ranges from 25 to 30% by mass and makes an excellent feed for livestock.