ridecamp@endurance.net: Re: Minerals

Re: Minerals

Susan F. Evans (suendavid@worldnet.att.net)
Fri, 18 Apr 1997 21:32:48 -0700

henslee wrote:
>
> Thanks for your response, Susan. No, the potassium levels are not high enough to
> cause muscle weakness nor cardiac arrest, thank goodness. It only
> happened one time and he had been fed alfalfa cubes the night before,
> so I thought maybe the alfalfa had something to do with it; but the
> potassium scenario was a possible explanation given by a feed rep--who
> knows nothing about endurance horses. My husband was the one doing the
> discussing with the rep and I'm wondering if the rep said phosphorous
> instead of potassium.
>
> Anyway, appreciate the time you took to give me your input.

Hi again,

Well, phosphorus doesn't sound like the culprit causing slow
recoveries either, BUT when you mentioned alfalfa, that rang a big bell.
Alfalfa, especially if it's really green and rich, is high in protein,
sometimes really REALLY high. All that protein gets degraded to
nitrogen in the blood plasma in the form of ammonia (yup, same stuff you
clean windows with). Ammonia (surprise surprise) is not only of no use
to the horse, it's toxic and so the body wants to get rid of it.
Primarily it's going to be excreted through the kidneys via urine, which
is why horses in box stalls on high-alfalfa diets stink to high heaven.
(By the way, don't get worried at the thought of window cleaner in your
horse's system---it's in low concentrations and the body is well
designed to deal with it. Not a big deal, just a nuisance).

However, here's the POSSIBLE connection to slower recovery/cooling
rates. The body will also attempt to get rid of the excess nitrogen
through the skin via sweat. The resulting sweat is thick and lathery,
instead of being thin, clear and relatively odorless. The lathery sweat
takes longer to evaporate, so the cooling effect is decreased.

In addition, the metabolic process of converting excess protein to
energy is more "expensive" than are the processes that convert fats or
carbohydrates to energy. So horses on a high protein diet tend to have
slightly higher body temperatures, and therefore are already at a slight
cooling disadvantage against horses on a low protein diet that are
running at a lower body temp. So the high-protein horse will have to
sweat more to cool himself, but then again runs into the barrier of not
getting maximum cooling from sweating, because the sweat is thick and
lathery. During an endurance ride, this could make the horse more prone
to dehydration, or at least needing more water to maintain and cool
himself.

Last, but not least, because the excess nitrogen/ammonia is primarily
excreted through the urine, the body will produce more urine than normal
to get rid of the ammonia. Normally horses will just drink more water
to avoid dehydration, BUT what if that horse happens to be out doing an
endurance ride on a hot day and doesn't have free access to all the
water he needs? It's not life-threatening, but again, this horse is
more prone to dehydration, and therefore the associated problems like
colic and impaction, than is the horse on a low-protein diet. Again,
nothing to panic about, it's just a disadvantage.

I don't know what your horse normally eats, but some horses are more
intolerant to high protein levels than others. If you fed him alfalfa
cubes the night before, and then observed a marked difference in his
recoveries the next day, it MIGHT be the protein that's causing it, and
it MIGHT be that your horse is more sensitive to it than other horses
might be. Alfalfa cubes are usually around 15-16% protein which is not
incredibly rich, so if you saw an effect from just cubes, you might want
to try it again (not before a race, of course) to see if the same thing
happens again. If it does, then it sounds like your horse doesn't
tolerate alfalfa well.

I hope this answers the question/mystery for you. Let me know if I can
help answer any questions for you, I'm happy to help.

Susan Evans

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