What do you do if a cow eats too much ground corn?

Just keep an eye on her to see if she bloats up or not. You will notice a bulge on the upper left side behind the ribs if she is bloating. If there's no sign of that, then don't worry too much. If she's got access to roughage (like hay), she should be fine. But, as mentioned above, keep an eye on her and have the vet's number handy in case it gets serious.

When it gets serious, she won't be eating, she'll be kicking at her belly, standing around, acting lethargic and moving around like she's uncomfortable. The bulge on her side, as mentioned above, will be noticeable.