You must have noticed that the cows continuously chew something even if there is no fodder in front of them. What is the reason behind it?
It is the swallowed food before which comes back to the mouth for proper chewing
Cows, buffaloes and other grass-eating animals quickly swallow the grass and store it in a part of the stomach called the rumen. Here the food gets partially digested and is called cud. But later the cud returns to the mouth in small lumps and the animal chews it. This process is called rumination and these animals are called ruminants.