During the distillation of wheat to produce whisky, two residual products are formed. These are the spent grains and a thick syrup resulting from evaporation of the liquor remaining after the whisky has been distilled off. These by-products may be combined to form undried dark grains (UDG) or further dried and pelleted to form wheat distillers dark grains (WDDG). UDG and WDDG were evaluated as feeds for ruminant livestock.

WDDG had the appearance of a typical concentrate pellet, dark brown in colour with a molasses like malty odour. UDG was lighter brown in colour but formed a dark brown surface crust on exposure to air. The bulk of the material had a granular putty-like texture and a smell akin to that of WDDG. Compositions of the two by-products and that of distillers dark grains derived from barley fernentation alone are given in Table 1.