Distillers' dried grain with soluble (DDGS) is a by-product of bio-ethanol fermentation, which involves dry milling for starch-rich cereals including maize, rice, and barley.

It is an efficient alternative to corn and soybean-based animal feed due to their high protein component. Most ethanol plants are dry-grind facilities that extract starch from corn to produce ethanol. The remainder of the corn kernel, after ethanol production is complete, is used to produce wet distiller grains (WDG) or dried distiller's grains (DDG).

DDGS has a longer shelf life (almost indefinite) than normal corn and soybean meal, making it a valuable food source for animals and livestock. Furthermore, the longer shelf life ensures DDGS can be shipped anywhere. Because it is abundant in crude protein, fat, fibre, vitamins, and minerals, DDGS is increasingly used as aquaculture and animal feed. DDGS has been utilised in a wide range of experiments to produce organic acids, methane, biohydrogen, and hydrolytic enzymes. While DDGS is high in macronutrients, it must be pre-treated before the fermentable sugars may be released. Because of its concentrated energy and protein content, the same quantity of DDGS is healthier than traditional feed.