Selenium (Se) is an essential trace mineral for livestock. White muscle disease, also known as nutritional myodegeneration, results from clinical Se deficiency and was discovered in Oregon in 1958. It is characterized by muscle weakness, heart failure, unthriftiness, and death. Sub-clinical effects of Se deficiency result in poor livestock performance.

  • Selenium deficiency is caused by low Se intake, which correlates to limited Se availability in soils, and thus, forages grown on those soils.
  • Livestock forage, whether range, pasture, or hay, generally reflects the available Se content of the soil on which it is grown.
  • Forage supplemented with Se can be fed to livestock. Concerns about Se toxicity are much less, intake of Se is more consistent, and retention of Se is much greater when feeding a Se-fortified forage.

The potential for using Se as a fertilizer to increase forage-Se concentrations in livestock feeds has been demonstrated by over 15 years of research at Oregon State University.

  • This practice can potentially overcome the inconsistent intake of salt-mineral mix Se supplementation.
  • Supranutritional amounts of Se can be provided safely with Se fertilization.

Our work is focused on establishing guidelines to produce Se-fertilized forage and hay in order to enhance forages fed to ruminants

  • We have shown that sodium selenate is the form of Se most efficiently taken up by plants.
  • The recommended level of application is 5 to 10 grams of actual Se per acre in order to achieve adequate levels in forage. Sodium selenate, for example, is 41% Se.  An application rate of 12 to 24 grams of sodium selenate per acre will provide the recommended 5 to 10 grams of actual Se per acre.

In particular we are studying the effects of Se fertilized forage (thus, increased Se intake) on immune responses, cattle health, and cattle production.  We also have multiple studies in sheep.