When a cow chews her cud, what is she doing?

• A. Eating fresh grass
• B. She is chewing her partially digested regurgitated food
• C. Swallowing already digested food
• D. Chewing food for the first time

Answer: (B)

Cud chewing is part of how cows process tough plant material through rumination. After the initial munch and swallow, the partly digested material sits in the stomach chambers where microbes start breaking down the cellulose. The cow then brings up a lump of that material and chews it again, grinding the fibers finer, increasing the surface area for microbes, and mixing it with saliva to lubricate and buffer the system. So when a cow is chewing her cud, she is chewing her partially digested regurgitated food that has been brought back up from the stomach, not fresh grass and not material that has already been fully digested.