No, because corn "stocks" don't exist. Corn STALKS, do though, and they may eat it, but it's really coarse roughage. They'd rather eat the corn cobs and leaves off the standing corn than the corn stalks. They'll sooner trample the stalks than eat them, really.

A few, but too many bloat the cow dangerously.

Depends. Idk if anyone has seen a cow before doing that

No..