Chapter 36 – Selenium

Publisher Summary This chapter discusses selenium (Se) in detail. Selenium deficiency and toxicity are problems which have caused extensive financial losses in the livestock industry and have been extensively researched. Selenium is an essential nutrient that has a relatively narrow window between ingested amounts that result in deficiencies and those that cause toxicosis. The selenium status of an animal depends on the forages or feed that has been ingested. Selenium deficiencies are very common in areas with low selenium concentrations in the soil. Because of the essential nature of selenium and environmental occurrences, poisoning cases from both natural plant selenium exposure and nutritional overdoses are common. Although much research has been conducted with regard to selenium poisoning and a lesser amount on the reproductive effects, the exact mechanism of these toxic effects in the body are still not clearly defined. Acute oral selenium poisoning occurs with sudden exposure of selenium ranging from 2.2 to greater than 20 mg/kg of body weight. Impaired immune function can directly affect the fetus or neonate in preventing them from mounting an appropriate response to true pathogens or opportunistic pathogens. The lack of or poor passive immunity can render offspring very vulnerable to disease and potential mortality. The most effective treatment of selenium toxicosis is to prevent excessive exposure. The primary treatment protocol for both acute and chronic selenium poisoning is supportive care. Low selenium, high-quality, high-protein diets reportedly are used in the treatment of chronic selenosis.