Selenium in crops in the United States in relation to selenium-responsive diseases of animals

Abstract

Selenium-responsive diseases of livestock occur frequently in the United States and have been responsible for serious economic losses. White muscle disease (WMD) of lambs and calves is perhaps the most common of these disorders. The occurrence of WMD is related to the geologic nature of the soil parent material (19). There is also evidence that regional patterns of occurrence of WMD are related to regional differences in the Se concentration of feed crops (3). In the U. S., there are also areas where Se toxicity has been evident in livestock. These areas have been studied extensively, and the distribution of geologic formations that form soils capable of producing high-Se plants has been established (14, 17, 21). This report presents a map of the U. S. showing areas where the Se content of plants is adequate to protect animals from WMD, and areas where low levels of Se in plants may lead to Se-responsive diseases in animals, and describes how it was prepared. A similar survey of plant Se levels has been reported from western Australia (9).