Whitetails are ruminants, meaning they are equipped with a four chambered stomach. An interesting characteristic about the ruminant's stomach is that it allows the animal to gather a lot of food at once and then chew and digest it later. The four chambered stomach is needed to process the large quantities of low nutrient food that deer eat.
Depending on the type and abundance of food, the deer can fill its stomach in about one or two hours. When a deer eats, food is chewed just enough to swallow. The food then passes down the esophagus into the stomach.
The deer has a four section stomach similar to that of cattle. The food goes into the first section (the Rumen) which acts as a fermentation chamber. Most of the digestion occurs in this area of the stomach. Deer depend on billions of micro-organisms that live in its stomach to break down the food components, and convert them into materials that can be used by the deer's digestive system. Almost half of a deer's energy is produced from the acids absorbed through the walls of the Rumen.
After the deer has filled its first stomach, it will lay down to chew its cud. After chewing its cud for awhile, the deer re-swallows the food, which then passes to the second portion of the stomach (the Reticulum). The Reticulum's main function is to filter out foriegn matter. This process takes roughly 16 hours.
The food material then passes on to the third stomach (the Omasum), which absorbs most of the water from the food. Then to the forth stomach (the Abomasum) which produces acids for more digestion and absorbtion.
The food material then goes through the intestines and everything that isn't digested is passed off as waste droppings.
A deer will urinate and deficate nearly a dozen times a day.