OBJECT #9: Cow Magnets

    These are cow magnets.  If you’ve never heard of a cow magnet, you are probably scratching your head wondering is this is a joke.  Seriously, these are cow magnets and they are used with cows. Cows are not very discerning grazers.  They will pick up bits of metal along with grass.  Nails, staples and broken pieces of wire fence have been known to lurk under clumps of grass in pastures, and these metal bits end up in cows’ stomachs.  Cows have four stomachs, one of which is the famous rumen, full of bacteria and other microorganisms that digest the grass.  A cow would not be able to live on grass alone without the help of these microorganisms.  This is because animal digestive systems cannot break down the cellulose wall around plant cells.  The nutrients are inside the cell and the wall must be broken down in order to release the nutrients.  Microorganisms produce the right enzymes for breaking apart cellulose.  Ruminate animals have the largest number of microorganisms living in their gut, so they are the ones that can live on nothing but grass and hay.

    The bits of metal in the cow’s stomach can cause damage, of course, but the most damage is done when those bits of metal get all the way into the intestines.  At some point during the last century, a farmer had the brilliant idea of making a cow swallow a large magnet.  The magnet is too large to pass from the stomachs into the intestines, so the magnet becomes a permanent resident in one of the stomachs, often the rumen.  All the bits of metal are attracted to the magnet and are thereby kept from going into the intestines.

    At first they used the smooth type of magnet.  The problem with this type is obvious.  Yes, the metal bits stick to the magnet, but then the magnet can become a mass of prickly bits of metal.  Someone eventually figured out how to design a plastic housing to surround the magnet.  The metal bits are drawn inside the outer diameter of the plastic housing, so hopefully only the smooth plastic will touch the sides of the stomach.

    Young cows are forced to swallow one of these magnets very early in their life.  The magnet then (hopefully) stays inside stomach for the life of the cow.  As far as I know, no attempt is made at recovering the magnet when the cow expires, although I suppose maybe butchers who are cutting up cows for use as meat for our dinner plates, might rescue a magnet if and when they came across one.  I think the magnets are cheap enough that farmers don’t worry too much about recycling them.

    Why do I have cow magnets in my basement?  My husband comes from a dairy farming family.  I think he picked up a few while at the farm years ago, and they have been in my basement collection ever since.  I’ve used them occasionally in my science classes because they are actually fairly strong magnets.