What do ruminant animals do?

Ruminants are mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The process, which takes place in the front part of the digestion system and therefore is called foregut fermentation, typically requires the fermented ingesta (known as cud) to be regurgitated and chewed again. The process of rechewing the cud to further break down plant matter and stimulate digestion is called rumination. The word "ruminant" comes from the Latin ruminare, which means "to chew over again".

There are roughly 200 species of living ruminants include both domestic and wild species . Ruminating mammals include cattle, goats, sheep, giraffes, yaks, deer, antelope, and some macropods (kangaroos). It has also been suggested that notoungulates also relied on rumination, as opposed to other antlantogenates that rely on the more typical hindgut fermentation, though this is not entirely certain.