Document Type

Thesis - Open Access

Award Date

1985

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Ivan S. Plamer

Abstract

Selenium occurs in the earth's crust in varying concentrations. It is crystallochemically related to sulfur, and sulfide ores frequently contain selenium. The commercial production of selenium is usually as a by-product of other mining operations, especially copper mining. It occurs in different oxidation states depending on the pH of the soils. At acidic pHs the predominate form is selenite. That present as selenite is bound to a high degree by iron colloids in soils and is thus not readily absorbed by plants. Once taken up by plants selenium becomes, to varying degrees, available to animals. Selenium can be either harmful or beneficial to animals. In 1957 Schwarz and Foltz demonstrated selenium to be the active part of "factor 3" which protected against dietary necrotic liver degeneration in rats fed low selenium diets, thus establishing its essentiality. Since then selenium has been shown to be essential to many species. Some effects of selenium deficiency are: nutritional myopia (white muscle disease), unthriftiness, and low lambing and calving percentages in sheep and cattle, exudative diathesis, nutritional muscular dystrophy, and nutritional pancreatic dystrophy in chickens, and muscular necrosis, decline in reproductive efficiency, and locomotor incoordination in swine. Selenium is known to be a component of the enzyme glutathione peroxidase, and signs of selenium deficiency in animals have been correlated with decreases in tissue glutathione peroxidase activity. The role of selenium as a toxicant has been known since 1934 when Franke and Potter found it to be the cause of the disorder known as “alkali disease”. This disorder was a serious problem to homesteaders on the Great Plains, whose animals became ill, and eventually died although they received sufficient feed. Some symptoms of chronic selenosis are in cattle and horses, lameness and hoof malformations, loss of hair, loss of appetite, emaciation, reduced fertility; in poultry, teratogeny, resulting in decreased egg hatchability; in sheep, reduced fertility. Selenium poisoning is still a serious problem to livestock in parts of the Great. Plains, consequently, preventive measures have been sought. Van Vleet induced selenium deficiencies in ducklings by administering silver, copper and other metals. Sulfate has been shown to modify the toxic effects of selenium in studies by Halverson, et al. and Ganther and Bauman. Moxon discovered the protective effect of arsenic against chronic selenium toxicity. Selenium has also been shown to protect animals against the toxic effects of cadmium and mercury under some conditions. The following work was designed to determine the role of protein and amino acid composition as a factor in the difference in the toxicity of selenium fed in corn-based diets or wheat-based diets, using growth rate and kidney selenium content as the main criteria for evaluating the effectiveness of a dietary modification.

Library of Congress Subject Headings

Selenosis
Selenium -- Psysiological effect

Format

application/pdf

Number of Pages

41

Publisher

South Dakota State University

Rights

No Copyright - United State
http://rightsstatements.org/vocab/NoC-US/1.0/

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