A deer has one stomach, but it is divided into four chambers. Like other ruminants, a deer's digestive system allows it to survive on a typical diet of leaves, glass blades and other plant parts.
The first chamber of the deer's stomach, the rumen, is used for food storage. This allows the deer to eat first and digest later. A deer can bring food stored in the rumen back up into its mouth to chew again in a process called ruminating. The reticulum contains microorganisms that break down the plant parts through fermentation. The omasum extracts water from the processed food to keep the deer hydrated. The food then enters the final chamber, the abomasum, for further digestion before it moves on to the intestines.