The micromineral selenium plays a vital role in equine immune function, especially in the mare and foal. Selenium transfer through the placenta and milk has been shown to influence neonatal selenium status in livestock, but it remains unknown if the selenium source affected transmission from mare to foal.

To that end, a research team–led by Julia B. Montgomery, MedVet, PhD, Dipl. ACVIM, from the Department of Veterinary Biomedical Sciences at the Western College of Veterinary Medicine–recently carried out a study examining the effects of organic or inorganic formulations of the mineral on mares’ and foals’ selenium levels. In addition they measured several immune function parameters in the foal.

Montgomery and colleagues fed 20 pregnant Standardbred mares identical balanced diets (which included selenium-deficient forage) starting two months prior to foaling and continuing to one month post-foaling. The team randomly assigned the mares to consume 0.3 ppm of either organic or inorganic selenium in addition to their regular rations.

The team collected colostrum and milk from each mare and blood samples from mares and foals to determine the animals’ selenium status