yes they chew cud. Cud is the food that they have swallowed and they have it come right back up and restart the chewing process all over again and this is called regurgation.
Because it's a part of their normal digestive processes. They eat hay and grass whole, so when they are resting (usually when they're bellies are full), they regurgitate the partly digested matter...
They are re chewing undigested feedstuffs. Cattle are designed to continuously eat until they have filled their first stomach (the Rumen). When they are safe from predators, they will enter their...