Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science


During the early 1900's, many stockmen in the western Great Plains suffered huge economic losses due to poisoning of their livestock through consumption of seleniferous plant material. Some were forced to discontinue raising livestock entirely and turned to grain farming. However, grain produced on land high in selenium was discounted on the market. Today, this grain marketing problem does not exist to the extent of that of the early 1900's. Selenium has more recently been recognized as an essential micronutrient for several species including swine. The Food and Drug Administration (FDA) has approved sodium selenite and sodium selenate as supplements to pig starter diets up to a level of .3 ppm of selenium. In view of this, the potential exists for selenium poisoning to occur through accidental contamination, incorrect mixing or incorrect formulation of the diet. Reports of selenosis in swine are limited and not well documented. Selenosis in swine has been experimentally produced, but seldom were the experimental objectives to establish the maximum level of dietary selenium that could be tolerated without affecting pig performance. The level at which selenium becomes toxic to swine is thought to be about 8 ppm. This value was derived from the initial selenium research of the 1930's, with considerable extrapolation from data of other species. Often the number of experimental animals used was not statistically sound. In addition, the improved methods of selenium analysis and purity of inorganic selenium compounds available today provide for more accuracy in experimentation. Diet composition has also become much more complex. Nutrient level of diets has increased and feed additives are commonly used. It is not known what effect these factors or other nutritional interrelationships may have on the level at which selenium becomes toxic. Due to the variability of selenium content in feedstuffs and because selenium is now approved as a feed additive, it is important to better define the level at which the element becomes toxic to swine when feeding modern diets. This research was conducted to determine the effect of varying dietary selenium levels, selenium source and dietary composition using the following parameters: 1. Pig performance as measured by daily gain, daily feed intake and feed conversion, 2. Blood composition, 3. Tissue selenium concentration, 4. Blood enzyme activity, 5. Liver weight as a percentage of body weight.

Library of Congress Subject Headings

Swine -- Feeding and feeds

Selenium in animal mutrition


Swine -- Diseases

South Dakota State University Theses



Number of Pages



South Dakota State University