The main difference between ruminants and nonruminants is that ruminants have stomachs with four chambers that release nutrients from food by fermenting it before digestion. Most ruminants, except llamas and camels, have hardened gums instead of upper front teeth, and all have split hooves.
When ruminants chew and swallow their food, it enters the rumen, which is the first chamber of the stomach. Beneficial bacteria in the rumen break down the fiber in the food, releasing proteins, fatty acids and B vitamins before the food passes to the reticulum. The reticulum prevents large pieces of food from moving deeper into the stomach, returning large pieces to the rumen in ball-like masses. The animal brings up the fermented ingesta, or cud, and chews it again. Finely chewed food passes from the reticulum to the omasum and finally to the abomasum before moving to the small intestine.