Q1.
I have seen cows keep chewing the food even when they are not actively grazing or eating anything. Why?
Answer
Because the cow is ruminating — chewing food it had swallowed earlier.
- A cow, like a buffalo, partially chews the grass and swallows it quickly into the stomach. Grazing is done fast, in the open.
- In the stomach, the grass is partially digested.
- Later, when the animal is resting, the partially digested food is brought back to the mouth and chewed slowly and thoroughly.
- This process is called rumination, and such animals are called ruminants. A cow spends about 8 hours a day just chewing.
- The thoroughly chewed food then passes down the alimentary canal again for further digestion.
Why it happens: grass is tough and full of fibre, and cannot be broken down in one round of chewing. Swallowing first and chewing later lets the animal collect a lot of grass quickly in the field — where it is exposed to danger — and then do the slow work of grinding it in a safe place.
Did you know? The large first chamber of a ruminant's stomach is called the rumen (labelled in Fig. 9.6). The word "ruminate" in English also means "to think something over slowly" — borrowed from exactly this habit of the cow.