As for the Vit. E--this is usually administered with Se because it
helps the body metabolize Se. Your assay indicates a rather low amount
of Vit. E based on the IU listed; however, Vit. E is also readily
available through the food chain. I have heard that you actually cannot
supplement artificial Vit. E in the quantities necessary--horses are
better able to secure the amount necessary for good nutrition from high
quality forage. Anyway, Vit. E isn't what you need to worry about. If
the feed company has developed a product designed to be the right balance
for your area, then stay within their guidelines AFTER you have confirmed
what YOUR horse's baseline is.
Diane @ Safe Haven