"Miro", the Hereford bull. Photos by John Klar One great benefit of cows is their resilience — rugged, and uncomplaining. But even cows have their Achilles heels; or, in this case, an Achilles rumen. It is easy for such big eaters to ingest rusted metal or old tacks in feed or just milling around munching on old shingles or whatever they find to sample. This is called “Hardware Disease” (or, traumatic reticuloperitonitis) and can become very serious in both beef and dairy cows. Some farmers routinely deposit one or two “cow magnets” in all their cows, where they will remain their entire lives as precautionary prophylactics, More often, a farmer will see the signs -- kicking the belly, an arched back or uneasy gait, laying down and getting up in discomfort, a drop in feed consumption or milk production.