Neat - For neat stuff you found

There's lots of machinery involved in processing hay and silage into feed. Any broken part, such as the tine of a rake, could end up in the feed. There's no good way of screening that out once it's baled or in a silo/bag.

Of course it's best to avoid contaminating areas with metal debris, but there's still plenty of potential sources for contamination that aren't feasible to elliminate.