It is my understanding that you can feed up to 30% of a horse's calories
from fat. Two cups seems like a lot but I do not know the total content of
your diet. I suggest contacting your local vet school nutritionist or the
local extension office. They can point you in the right direction.
Do not feed extra selenium! Have your mare blood tested by your vet and
get an analysis. If they show that she is Se deficient, then increase your
supplementation. Selenium is very toxic in very small doses. The effects
of a high fat diet are a bit too unpredictable and if you are feeding a
ration balanced for your region, I would not double it until you talk with
a nutritionist and check with your vet for a blood test if you feel she is
still Se deficient. Remember, if you want to increase something, you can
feed more Vit E.
Ohio is also Se deficient and after talking to my nutrition professor, I
stick to the directions and feed the max recommended amount during
competition season and cut back to maintenance levels in the winter.
Shannon Loomis and Quail Meadow Star