For the Health of It
Selenium Status in Horses
Reprinted with permission from the October 2013 issue of Equine Disease Quarterly
Selenium (Se) plays a role in the antioxidant
mechanism of the body, and has also been shown to
affect the immune system in many species. Additionally, Se is incorporated into at least 25 different
selenoproteins. The synthesis of these selenoproteins depends on the availability of Se within the
body. Herbivores rely on plants to meet their Se
requirements, while plants obtain Se from the soil.
However, soil Se concentration varies geographically, resulting in inconsistent dietary Se intakes across
regions in grazing animals.
Areas that tend to be low or marginal in Se include parts of the Eastern United States, New Zealand, Northeastern China, Europe, Egypt and South
Africa. Horses kept in low Se areas, or exclusively
fed forage and unsupplemented grains produced in
low Se areas, may become Se deficient over time.
Central Kentucky is known to be marginal in Se.
Therefore, the long term effects of dietary Se intake
on the Se status, immune function and exercise
response of the horse was studied at the University
of Kentucky in collaboration with the Alltech–UK
Nutrigenomics Alliance.
Horses grazing low Se pastures were fed a Se-free
supplement for 28 weeks. Then, over the next 28
weeks, a third of these horses was supplemented
with 0.3 mg Se/kg dry matter and a third received
the same amount of Se, but as sodium selenite. The
remaining horses stayed on the unsupplemented
diet. Throughout the study a fourth group of horses
was given a supplement prov Y[