Oats is an energy feed, so in very general terms, more energy on board
means more energy available to climb the walls. I also remember hearing
one of my professors (an equine nutrition Ph.D, so I'm willing to
listen) say there is a specific protein in oats that is not present in
other grains that causes an "allergic" reaction in some horses, such as
high behavior. I've also heard this from others at some of the ENPS
meetings, but I haven't seen any specific research on it (although I
haven't really gone looking, either), so I really don't know. I'm just
passing on what I've heard.
However, if your barn is feeding oats to help keep the horses warm, you
might suggest feeding your mare more hay instead. Oats and other grains
contain higher levels of soluble carbohydrates which produce very little
heat during digestion (notice I said "heat", not "energy"). Hay
contains lower levels of energy but much higher levels of fiber, which
make the body work harder to digest, thereby producing heat---called,
amazingly enough, "heat of digestion". This stokes the horse's internal
furnace and keeps them warm in cold weather. Feeding excess energy in
the form of grain will add body fat, which adds some insulation (ask any
whale), but it won't happen immediately and therefore won't help keep
your mare warm that very day.
I think the general rule of thumb is increasing the hay ration by 10%
for every ten degress below freezing. Anyway, you might give it a try,
I think you'll find it a better solution than feeding oats, especially
if she gets too gymnastic being fed grain.
Susan Evans