Avoid relying on salt blocks to provide adequate copper supplementation. Goiter, weak calves, and an increased number of cases of foot rot, lumpy jaw, and woody tongue in cattle. Stable iodine compounds can be added to loose salt mineral mixes. Salt blocks are not a reliable source of iodine supplementation. The same problem occurs to a lesser degree with copper compounds and selenium compounds in salt blocks.
Diagnosis is very simple in California with the current diagnostic laboratory system.
A blood sample submitted by your veterinarian to the diagnostic laboratory will quickly and cheaply determine the selenium status of the herd or animal in question. The injections provide selenium supplementation very rapidly and are very effective for therapy. However, they provide only partial supplementation for 28 to 45 days. Thus, if injectable selenium is the sole means of supplementation, injections would have to be repeated 8 to 12 times per year. Selenium added to salt mineral mixes at concentrations up to 120 ppm can be very effective at maintaining adequate selenium in cattle.