What is a Ruminant?

 

Bison eat and digest their food in a very unique way.  They like to eat prairie grasses, and they have special teeth on their lower jaw that helps them clip off the grass.  Bison eat grass by wrapping their tongue around it and pinching it off between their tongues and lower teeth.  They swallow their food practically whole.  Bison are ruminants  Ruminants have stomachs made up of four compartments which help them digest food.   
When eaten, food is first stored in the rumen, the first compartment of the stomach.  Some food goes directly to the second compartment which is the reticulum. 
Eventually, all the food goes to the second compartment, the reticulum.  Here stomach juices and bacteria begin to break food down and form it into cud.  When the bison are resting, muscles in the reticulum push the cud back up into bison's mouth.  There the cud is chewed and mixed with more saliva.
Then the cud is swallowed again to be further digested. It passes through the rumen, the reticulum, and into the omasum, which is the third compartment of the bison's stomach.  The cud is further digested there.
The final stop is the abomasum, the last of the compartments.  Here, cud is combined with stomach juices before passing into the intestines.
Why does it take four stomachs?  The grasses, forbs (weeds), and browse (woody plants), are very tough and hard to break down.  The bison's ability to use many different plant foods makes it a survivor when food (forage) is scarce.