Author
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Mayland, Henry |
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Submitted to: American Society for Surface Mining & Reclamation Annual Meeting Proceeding
Publication Type: Proceedings Publication Acceptance Date: 6/8/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Cattle and sheep require some selenium in their diet, but excess selenium may cause problems. When they eat plants containing 5 to 50 ppm Se they may develop selenosis. Symptoms include "blind staggers." However, the problem may not be caused by excess selenium, but rather by excess sulfur. Drinking high-sulfate water and eating plants high in sulfur may cause the problem. More information is being sought by the researchers. For now they recommend that livestock receive quality drinking water to reduce the incidence of blind staggers. Technical Abstract: High concentrations of selenium and sulfur often occur in over-burden soils and underlying shales associated with western coal mining areas. We discuss recent findings about selenium and sulfur forms in soil, their absorption and accumulation by plants, and their subsequent toxicity to grazing animals. Selenium absorbed by the accumulating plants is generally metabolized to non-protein forms, while that absorbed by the non-accumulating plants occurs predominantly as selenomethionine. Selenomethionine is readily absorbed by animals. In animals, both acute and chronic forms of selenosis are known. Death occurs when a large dose of highly-available selenium is ingested. One chronic form includes symptoms of inappetence, hair loss, hardening and extension of nails and hooves, reduced weight gains, and poor reproductive performance. Beath and Rosenfield identified "blind staggers" as another form of selenosis, but this disorder, more appropriately called polioencephalomalacia (PEM), occurred only in ruminants. Recent experimental evidence has shown that PEM is likely caused by excess sulfate. Cases of this disorder have been documented in the USA and Canada when ruminants have high sulfur intake from herbage and/or drinking water. |
