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Hi folks,

I was replying to a rider back east that needed some help regarding her
horse's feed and thought someone else might find the topic of 'hot feeds' of
interest.  So here it is copied below, edited appropriately to protect the
innocent. <g>

> We are moving from the NE to an enviroment where alfalfa is the > ONLY
feed fed to horses.  UGHHHH!  <snip>  People out there > keep in insisting
that grain and beet pulp are "too > hot" for horses in the desert, though
nobody can > explain to me what the heck THAT means.



Okey-dokey, I think I can offer a little perspective on the problems you're
up against.  First of all, the issue of beet pulp and grain being "too hot
for horses in the desert".

The more soluble and easily digested a feed is, the more likely it is to
affect plasma glucose levels and give that "sugar rush" that makes (some)
horses excitable and harder to handle---in other words, "hot".  The term
'glycemic index' is used as a comparative phrase between feeds that provide
a sugar rush versus those that don't.  Over the years, what is essentially a
slang phrase "hot" (as in excited) got all tangled up and confused with
"hot" (as in higher body temperature), which is an entirely different thing.

Easily digestible feeds like grain may make a horse hotter (as in more
excitable), but do NOT make the body temperature hotter.  In fact, it's
somewhat the opposite---because the body has relatively little work to do in
digesting the feed, there's little metabolic waste heat produced and core
body temperatures stay the same, which is a handy thing in very hot climates
like southwest Nevada.  Let's take that a step further and talk about
feeding fats for extra calories---fats are digested so efficiently by the
body that an actual cooling effect on core temperature has been well
documented.  That is, if your horse isn't dealing well with the heat, then
you can turn down that internal furnace a bit by using fats as a calorie
source instead of less digestible feeds.  In actual practice, though, there
is fairly little difference in heat production between fats and soluble
carbohydrates, such as grain.

As for beet pulp, it's a little lower on the glycemic index---easily
digested and provides relatively little increase in body temperature (less
than any hay, because beet pulp is more digestible), but generally, not much
of a sugar rush, because the processing removes virtually all of its soluble
carbohydrate (sugar) content.  However, a lot of the beet pulp commercially
available has molasses added back in, to reduce the fines and dust content,
and to help hold pellets together.  The smaller the pellet, the more
molasses.  Shredded is less likely to also contain molasses, but that
varies.  Some horses just don't tolerate molasses well (especially those
that are insulin-resistant) and so become nut cases.  In that case, try to
find a no-molasses-added beet pulp if you can.  In either case, beet pulp is
NOT a hot feed (as in higher body temperatures) and so can be entirely
appropriate for desert horses.

So let's talk about what *is* a hot feed (as in higher body temperatures).
The harder the body has to work to digest a feed, OR the more inefficient
the digestive process is in metabolizing that feed (which is not necessarily
the same thing), the more metabolic waste heat will be produced to maintain
or raise core body temperature.  Usually, the body has to work harder to
digest fibrous feeds, like hay and other forages, through the process of
microbial fermentation in the hindgut.  Horses actually aren't all that
efficient at fermenting fibrous feeds, so while there's a lot of heat
produced by hindgut fermentation, it's not nearly as much as more efficient
species like cows and sheep (building your house over the cow barn used to
be a traditional way of heating your house very nicely in Europe because of
all the heat thrown off downstairs).

What *does* tend to raise core temperatures in horses is the digestion of
protein.  Protein is easily digested, BUT the metabolic pathway is a fairly
inefficient one, with a relatively large amount of metabolic waste heat
thrown off in the process.  I don't have the numbers right in front of me,
but if memory serves, core temperature rises by about one degree for 4-5
hours after feeding a five pound flake of alfalfa.  One degree is actually a
lot if the horse is already using energy in a hot climate to cool himself.
So, by feeding straight alfalfa in a hot climate, you're adding a
significant amount of heat load to what the horse already has to deal with
just from the air temperature and sun.  As a result, the horse sweats more,
has to drink more, pees more and often has a slightly higher heart and
respiratory rate.

So when your future barn managers say that they only feed alfalfa, because
grain and beet pulp are "too hot for horses during the summer", they
actually have it backwards.  The grain and beet pulp might make the horse a
little more excitable than alfalfa will, because they are more digestible,
but grain and beet pulp are actually a much cooler feed when it comes to
core body temperature.  Think of which is more of an issue for your horse.
Is he a total nut case when he gets within the same zip code as a handful of
grain?  Or, does he stand in a stall sweating and getting colicky whenever
the temperature gets into the triple digits?

You might pass all this on to your barn manager and see if he's willing to
work out a deal to feed your horse something other than straight alfalfa.
Soaked beet pulp would be a good alternative, or feeding one of the
no-soaking-required commercial feeds based on beet pulp like Purina Complete
Advantage, Race Ready, Buckeye's Unbeetable or Nutrena's Sweet Rely.  Maybe
you can supply your own grass hay (there's plenty available in Nevada
according to my friends there) and hang a big supply in a haynet and ask
that they cut down the amount of alfalfa fed.

All of this is, of course, aside from the issue of increased incidence of
enterolith formation in horses fed Southwest grown alfalfa.  I won't go into
it here, but there's an article on my website at
http://www.shady-acres.com/susan/alfalfa.shtml that covers all that.

So, my bottom line recommendation for you would be to see if you can finagle
grass hay being fed as at least 50% of the forage ration.  If you have to,
50% alfalfa is do-able.  If there's no way and no how they will feed any hay
other than alfalfa, then just ask that they only feed very small flakes, no
more than about ten pounds a day TOTAL---just enough roughage for gut
motility and so he doesn't feel left out at feeding time.  Make up the
difference in calories with a gradual increase in one of the beet pulp based
feed like Complete Advantage.  It's formulated as a complete feed, so you
can gradually work it up to free choice and always available in the bin.  If
it's free choice, don't soak it, it's too likely to spoil in the heat and
the processed brands don't have to be soaked, unless your horse has a
history of choke, or when you're at a ride.  Once he's used to that, and if
he's still a hard keeper, try adding a cup or two a day of whole flax seed
to the mix for the extra fat.  Rice bran will also add some fat, but I'm
leery of too much phosphorus being provided along with the high protein and
magnesium content of the alfalfa.  Try the flax seed first.

If you can, get some alfalfa available and start getting him used to it
now---you NEVER want to switch feeds drastically and quickly.

Good luck!

Susan Garlinghouse, DVM MSc.




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