Rather than putting magnets in every cow why not clean the fields of injury causing debris?<p><a href="http:&#x2F;&#x2F;extension.missouri.edu&#x2F;p&#x2F;G7700" rel="nofollow">http:&#x2F;&#x2F;extension.missouri.edu&#x2F;p&#x2F;G7700</a><p>&gt; From 55 to 75 percent of the cattle slaughtered in the eastern United States have been found to have hardware in the reticulum. However, no damage or perforations of the reticulum was evident.<p>[...]<p>&gt; The magnet simply keeps foreign metallic objects adhered together in a ball, reducing the chances of penetrating the reticulum. Of course, the best preventive measure is keeping feed bunks, pastures, cow lots, etc., free of potentially hazardous objects.