Natural selenium-rich feeds manage selenium deficiency in Oregon sheep

Authors: Taylor, Joshua - Bret

Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: 9/1/2013
Publication Date: 10/1/2013
Citation: Taylor, J.B. 2013. Natural selenium-rich feeds manage selenium deficiency in Oregon sheep. The Oregon Sheep Grower. 29:5.

Interpretive Summary: A natural selenium-rich feed product was developed by the USDA, Agricultural Research Service, U.S. Sheep Experiment Station for the purposes of enhancing the long-term selenium status of grazing livestock. Our on-farm tests with this product in Oregon demonstrated that supplements and feeds manufactured from products that are naturally rich in selenium can be used in a short-term feeding program to rapidly enhance the selenium status of livestock and their nursing young. This enhanced selenium status lasted long after the selenium-rich test product was fed; in other words, a short-term feeding program was applied that resulted in long-term positive results.

Technical Abstract: A natural selenium-rich feed product (SePR) was developed by the USDA, ARS, U.S. Sheep Experiment Station for the purposes of enhancing the long-term selenium status of grazing livestock. In cooperation with Intermountain Farmers Association (Salt Lake City, UT), a bulk amount of SePR was manufactured and shipped to various cooperating sheep ranches and farms (locations) in Oregon for testing. Each location fed SePR for the first 22 to 40 days after lambing. SePR enhanced the selenium status of ewes and their nursing young. Depending on the locations, selenium content of whole blood increased 21 to 52% in ewes and 25% to 117% in nursing lambs. Locations that feed SePR for more days achieved greater enhancement of whole blood selenium in ewes and lambs. Lambs did not consume SePR and, thus, received the benefit of SePR through the ewes’ milk, which demonstrated that the best time to enhance selenium status of lambs is to feed SePR to the ewes during early lactation. Selenium content of wool significantly increased at all locations after SePR was fed to the ewes; the magnitude of selenium enrichment in wool was much greater than what was observed in whole blood. Based on previous work, enrichment of wool with selenium is similar to what is observed in skeletal muscle when SePR-like products were fed to sheep. Selenium that is incorporated in muscle tissue can act as a “selenium reserve,” which slowly releases selenium back to the body over long periods of time; an effect not possible with traditional selenium supplements formulated with sodium selenite. In summary, we demonstrated that feedstuffs that are naturally rich in selenium can be used in a short-term feeding program to rapidly enhance the long-term selenium status of ewes and nursing lambs.