A couple things from experience:

Even though there is not a lot of grain out there, there was probably a lot of nitrogen fertilizer put out for this corn and could be accumulated in the lower stalks. This could cause nitrate poisoning.

Make sure there is hay available at all times to cattle grazing unharvested, possibly high nitrate  stalks. Don't force them to eat the lower stalks.

Frankly I would NOT strip graze this corn but give them the run of it so they do not end up eating the lower stalks (where the nitrates are) for some time yet.

Should be ok if you are careful and watch them.

Jim at Dawn