About 3 out of every 4 dairy cows slaughtered for ground beef has some degree of hardware disease. In most cases it isn’t serious enough to puncture an organ and cause peritonitis, but it is certainly present in trace amounts to beef consumers. I imagine the problem is equally widespread in beef steers as well. You find roofing nails, bailing wire, food packaging ... all kinds of things; you put it in front of them and they will eat it.
Are we eating robobeef?
If cattle ate mostly grass then they would tend to consume a sufficient amount of minerals. However, if they are mostly being fed corn then I could see where they might have mineral deficiencies which they compensate for by eating whatever iron objects are ready to eat.