Abstract:
Oregon State University researchers made a significant discovery in 1958. They found that the underlying cause of white muscle disease is a dietary deficiency of the trace element selenium (Se). There is a fairly clear-cut relationship between soil, plant, and animal factors. Certain soils, including some formed by volcanic action in the Northwest within the past
10,000 years or so contain practically no selenium. As a result, plants grown in them are seriously selenium-deficient. This deficiency is passed on to animals eating these plants as fresh forage, hay, or silage as all or most of their diet. In addition to the amount of selenium in these volcanic soils, the supply is affected by intensive cropping practices. Irrigation tends to leach selenium out of the topsoil, and the application of some commercial fertilizers that result in higher crop yields reduces the percentage of selenium in the forage.
