When a cow grazes in a field, she often eats more than just grass. Cows can also accidentally eat metal objects such as nails, wire or staples. To stop this, a cow magnet is fed to a cow and travels to her first stomach (cows have four digestive compartments that are generally considered four stomachs) to stop her from digesting the metal. The magnet will settle in a cow's reticulum or rumen portion of her stomach, so if a cow eats any metal, it is attracted to the magnet and does not go any further.
If farmers, ranchers and veterinarians didn't feed cows the cow magnets, then cows would run the risk of developing hardware disease. This ailment occurs when metal objects become lodged in a cow's stomach, causing her to lose her appetite. For dairy cows, this means a loss in milk production. For feeder cattle (those used to produce beef), this means a loss in weight. Both are not only detrimental to the cow, but to the farmers as well.
Cow magnets initially were made of alnico and about 1cm by 8cm in size, in the shape of a capsule. Alnico is the acronym for aluminum (Al), nickel (Ni), cobalt (Co), but the compound also comprises iron, copper and sometimes titanium. Nowadays, cow magnets are usually five ferrite magnet spheres attached to a stainless steel or plastic capsule, the same size and shape as the alnico magnets. Ferrite is a ceramic compound derived from iron oxides.
Beyond the alnico and ferrite types of magnets, cow magnets also are available in ceramic or mineral supplement form. The ceramic magnet is made of strontium ferrite. It has an epoxy coating that is gentle on the cow and also prevents it from chipping. The mineral supplement magnets, which also are ceramic, release iron, strontium, calcium, copper and trace elements over time, maintaining the cow's health. With 5.5 pounds of pull, both magnet types are more powerful than the alnico.
When a cow magnet is designed with the focus of its magnetism at each end, it can harm the cow. In this case, the majority of metal objects the cow ingests, once attracted to the magnet, then protrude from it, possibly poking the inside of the cow's stomach and causing lesions. A properly designed magnet has the focus of magnetism at its middle, drawing all metal objects toward its center.
Farmers, ranchers, veterinarians and anyone who might purchase a cow magnet should be wary in their purchase because, sometimes, businesses will claim, intentionally or unknowingly, that they're selling an alnico magnet, when they're actually selling a regular stainless steel cow magnet. The two magnets look similar, but alnico magnets are more expensive. Stainless steel magnets are cheaper to produce, and this scam leads to the buyer overpaying and receiving a lower quality good.