Here's why they do this:
* Efficient Digestion: Cows are ruminants, meaning they have a four-chambered stomach. The rumen is the largest chamber where bacteria break down tough plant material.
* Cud Chewing: The cud is then brought back up to the mouth, where the cow chews it further. This helps break down the plant matter into smaller particles, making it easier for the bacteria to digest.
* Continuous Process: Cows spend a significant amount of time chewing cud, even when they aren't actively grazing. This process allows them to extract maximum nutrients from their food.
So, while it may look like they're chewing on nothing, they're actually re-chewing partially digested food to improve their digestion.