Some years, acorns are a BIG problem.
In heavy mast years, cattle with access to heavily-producing oaks - and, in my experience, it's more of an issue with members of the white oak group(white oak, bur oak, etc.) than the red/black oak group, though both can be a problem - will overconsume acorns. Gallotannins and other compounds in the acorns will damage renal tubules, with cattle succumbing to renal failure.
Deer & goats have proline-rich salivary proteins that bind the tannins, so they can eat them with no problem, but cattle lack those, and can't handle large amounts of acorns.
I've seen cattle in bad shape - you can pump 'em up with IV & oral fluids, laxatives, mineral oil, etc. - and they'll go right back to the oaks and start eating acorns again; it's like they have a death-wish and an unnatural craving for them.
Had a cow through the necropsy lab last week with a rumen full of buckeyes; producer had lost 3-4 cows over the preceding week - no way of knowing if that's what killed the others or not, but it's possible.