The ruminants bring back swallowed grass into their mouth and chew it for sometime.

The ruminants bring back swallowed grass into their mouth and chew it for sometime. Grass has cellulose. It is the carbohydrate which can only be digested by ruminants because they have rumen. When they eat grass, it is sent to the rumen where enzymes acts on it and softens it. Softened cellulose is called cud. It is sent back to the mouth where ruminants chew it for sometime.