DM is the standard abbreviation for dry matter, the solid material remaining after all water is removed from a food or feed sample. Expressing composition on a dry-matter basis allows fair comparison of nutrients across products with different moisture contents, from fresh forage to milk powders. Analysts determine it by oven drying to constant weight, and it underpins feed formulation, milk-solids calculations and yield computations throughout the food and feed industries. Feed mills quote rations on this basis so that farmers compare feeds fairly regardless of moisture.