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  • Red Dane Farming

Metal in Cows' Stomachs and How to Deal with It


Unfortunately, when grazing, cows do not only consume grass! Although cows should constantly be ‘chewing the cud’, when they take food in they swallow it without sorting it with their lips, and almost entirely without chewing, before regurgitating the grass to chew throughout the day. Thus, they are prone to swallowing whatever is in the way of their grazing path, and this includes any dirt, nails, wire or other small metal objects that are lying around. A study by the University of Missouri found that 55 to 75% of cattle slaughtered in the Eastern United States have hardware in their reticulum.


Small pieces of metal can become stuck in the walls of your cow’s reticulum, which is the second of a cow’s four stomach chambers. The metal is pushed into the  wall by contractions of the reticulum, and this causes surrounding organs to become irritated and inflamed, resulting in loss of appetite and thus a decrease in milk production. The stomach may even become blocked. This is known as ‘hardware disease’. In the worst cases, sharp pieces may even penetrate the heart through the diaphragm, resulting in pericarditis – swelling of the fibrous sac that surrounds the heart,  and causing the cow sharp chest pain. The risk of pericarditis is increased by compression of the uterus during late pregnancy, mounting during estrus and straining whilst giving birth. The symptoms of hardware disease will vary depending on which organ the metal has pierced. Common symptoms include the cow experiencing pain during lying down or getting up, and during defecation. She may move reluctantly and slowly and exhibit an arched back and quick, shallow breathing. A blood sample showing increased fibrinogen and plasma protein may indicate hardware disease. You can also use electronic metal detectors, and radiographs can show the location of the metallic item.


Cows should be given a cow magnet to swallow when they are 1 year of age. The images below show 1. A new cow magnet and 2. A cow magnet removed from a cow’s stomach after death. The magnet will remain in the rumen or reticulum for the duration of her life. The magnet should only be fed to the cow after fasting her for 24 hours.

The magnets collect any sharp metal objects the cow may swallow, and prevent them from approaching and penetrating the wall of the reticulum, thus preventing hardware disease. If the cow was not given a magnet as a calf, the magnet can be administered once symptoms of hardware disease are observed – the magnet can extract the metal from the stomach walls. A course of antibiotics can also be administered to combat any bacterial infections that may have been caused by the metal.

In a TMR system, hardware disease can also be prevented by good management of the ingredients that go into the feed mixer, making sure that they do not contain pieces of metal or wire or any other hard objects. A good stock feed supplier will have magnets on the processing line in their factory to capture any metal that might be in the food, and if conveyors are used on the farm to move food into the mixer, magnets can be placed on these as well to remove any metal.

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