April 2, 1998
Cows grazing pastures where there's debris from recent tornadoes or windstorms are at increased risk for a condition known as "hardware disease." Putting a magnet into the stomach of a cow can help protect her from hardware disease, says Ralph Farnsworth, veterinarian with the University of Minnesota Extension Service.
Hardware disease is the result of cows swallowing small pieces of wire, nails, or other small, metal objects," explains Farnsworth. "Cows do not chew their food thoroughly when eating, but rather, they 'chew their cud' later, bringing up food stored in their first stomach. When eating, they take in large quantities of food such as grass or hay and swallow almost immediately. If a mouthful of grass contains a small piece of metal, the cow will probably not even notice."
Farnsworth notes that windstorms can litter pastures with nails, fence staples, and small pieces of wire or other metal. Hay or silage harvested from fields containing debris may also pose a danger to cattle. A piece of metal picked up by a silage chopper may be cut into small pieces that are easily swallowed by a cow.
"After small pieces of metal are swallowed, they tend to remain in the reticulum, or second stomach, of the animal," says Farnsworth. "The sharp pieces of metal may pierce the stomach walls, allowing stomach contents to leak out into the body cavity. This can result in infections. The pieces of metal may also go through the diaphragm of the cow and cause infection of the heart or lung cavities, leading to death in some cases."
A magnet in a cow's stomach will collect the small pieces of metal and hold them in place so that they cannot move around and injure the animal, says Farnsworth.
Magnets used for this purpose are about two and one-half inches long and a half inch in diameter, or about the size of a man's thumb. They can be administered with a balling gun, like those used for pills. The magnet will move into the second stomach compartment of the cow. It will usually remain there for at least a year, but may eventually be expelled through the digestive tract.
Farnsworth recommends placing a magnet in all cows grazing fields containing storm debris. The magnets are relatively inexpensive, and are available through most veterinarians.
Farnsworth adds that it is important to clear meadows of debris before harvesting hay or silage. And if a feed mill, grinder-mixer, TMR mixer, or forage harvester is equipped with a magnet to remove metal from feed, check to make sure the magnet is in place so that it works properly.
Farnsworth is a faculty member in the College of Veterinary Medicine.
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Source: Ralph Farnsworth, 625-3130
Writer: Joseph Kurtz, EDS, (612) 625-3168, pkurtz@extension.umn.edu
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