Dry matter is what remains after all of the water is evaporated out of a feed: grain and fresh or dried forages. Fresh pasture has high water content and will have a lower percentage of dry matter than an equivalent weight of dryer feed, such as hay or grain. Dry matter is an indicator of the amount of nutrients that are available to the animal in a particular feed.
Livestock need to consume a certain amount of dry matter per day (measured in lbs or kg/day) to maintain health and production. The daily amount of dry matter needed depends upon several factors including, weight and stage of production (e.g., lactating, pregnant, weaning, finishing). Dry matter intake (DMI) can be estimated by using published reference tables that provide the percent dry matter in various dry (hay and grain), fresh, and ensiled feeds. There are also methods to measure the actual dry matter in feed.
Under the NOP regulations, ruminants must obtain at least 30% of their dry matter intake (DMI) from grazing on pasture during the grazing season.