Protein, Praises
and Woes
~ by Gretchen Topel, Equine Nutritional System
Protein is absolutely necessary for the body to survive, but
an overload of protein will break down the tissues, organs,
and structure of the body over time. Additionally, a horse that
consumes too much protein will be at an even greater risk of
contracting diseases and be predisposed to other symptoms such
as hypothyroidism, tying up, kidney problems, and arthritis
to name a few.
Without proteins, DNA, enzymes, and hormones would not exist
as these substances are primarily composed of proteins. Imagine
how out of balance a horse's body would be if they did not have
enough protein! Some horses, but very few, do suffer from too
little protein in the diet, but mostly, I find that if a horse
is a having a severe issue, they are presently consuming too
much protein in the form of alfalfa and/or a high protein grain
formulation.
What is the ideal balance of protein in a horse's diet?
No mammal should consume more protein than what was available
from his or her mother's milk. Mare's milk is 12% protein. Colostrum
is higher in protein, around 18%, but drops to 12% for the duration
of lactation. When the protein level of the total ration is
increased beyond 12%, the body becomes what is termed "over-acid".
What this means is upon digestion, feed is either acid forming
or alkalizing to the system. For example, alfalfa is acid forming,
most grass hays are alkalizing, apple cider vinegar is an acid
yet upon digestion leaves an alkaline residue, grains are acid
forming as well, and fats and minerals are alkalizing. As I
have written in the past articles, balance is always the key.
The same goes for balancing protein in the horse's diet.
When the diet exceeds 12% total protein, the body has several
buffering mechanisms available to offset the deleterious effect
of over-acid. Because the heart will not even beat in an over-acid
body and the organs must be bathed in an alkaline medium, it
is a top priority to keep the body alkaline (apart from the
stomach acid). Here is a breakdown of the buffering mechanisms:
1. Because minerals are alkalizing, if minerals are not readily
available in the blood stream, the body will pull the minerals
from the bones, ligaments, and tendons to buffer the acid.
2. The body will retain water to dilute the acid, thus the
horse can be mistaken for being in "good flesh". Once the high
protein feed is taken away, the horses will literally urinate
themselves thin in a few days to a couple of weeks! They are
not losing lean muscle tissue, they are losing the retained
water.
Alfalfa
Most horses can handle about 10-20% alfalfa in their diet.
Because alfalfa's roots can reach about 30 feet under ground,
alfalfa can provide some different nutrients apart from grasses,
whose roots grow only a few inches into the soil. At 18-24%
protein, alfalfa can help increase the protein levels of the
total ration, especially when feeding grass hay such as timothy,
which in some cases is only around 6% protein. Horses will lose
condition and become lethargic on too low of protein. Going
back to the concept of feeding horses no more than 12% protein,
you can see how feeding a diet of straight alfalfa or even 50+%
alfalfa, will cause acidosis in the body. I will go through
some of the symptoms that horses can and will face if fed a
diet that is too high in alfalfa. Just a word of caution: horses
that are Cushing's/hypothyroid/insulin resistant ("easy keepers")
do best on no alfalfa at all. Also, horses that are fighting
off a serious infection (i.e. West Nile virus) or who are recovering
from colic surgery, founder, and the like, will do much better
on straight grass. Alfalfa is more difficult to break down with
its higher protein ratio, so it is best for these horses to
consume a high quality grass hay such as brome or orchard grass,
or a grass mix of timothy, orchard, brome, and bluegrass is
a good choice as well.
Symptoms arising from too much alfalfa (also goes for high
protein grain formulations)
Hypothyroidism, thumps, bad attitude
Alfalfa typically contains inappropriate levels of calcium
to phosphorus, 5:1 to be exact. A balanced ratio of calcium
to phosphorus is 1.5 parts calcium to 1 part phosphorus. The
excess calcium in alfalfa interferes with parathyroid function
and can lead to thumps, muscle cramps and tying up.
Excess calcium also interferes with the absorption of iodine,
a mineral necessary for proper thyroid function. Many horses
on a high alfalfa diet become hypothyroid as the thyroid gets
lazy and tired from being malnourished. Symptoms are cresty
necks, overweight/easy keepers yet always hungry, dry, flaky
skin, cinchy and skin-sensitive, loss of topline muscling and
hair condition and unwillingness to give and flex due to increased
water retention.
Tying Up
According to research performed at Colorado State University
and in Sweden, excess dietary protein decreases T4 levels. Optimum
T4 levels are necessary for horses to metabolize glucose (blood
sugar) properly. When a horse is under strenuous exercise, higher
glucose levels are required to fuel the muscles. Higher glucose
levels also delay the onset of lactic acid buildup in the muscles
and blood. Too much lactic acid causes the muscles to lose their
ability to contract and relax properly. In this state the muscles
stay contracted/tied up.
As we learned from our past discussion on mineral balance,
we know that too much calcium depletes magnesium. Magnesium
is absolutely essential to relax the muscles after the contraction
phase. In the CSU and Sweden studies, higher magnesium levels
were found to increase the production of T4 thyroid hormone.
Because increased estrogen depletes magnesium, mares and fillies
tend to tie up more frequently on high alfalfa diets as estrogen
is increased during their heat cycles.
Kidney problems
If the barn smells like ammonia, this is a bad sign. Some of
the protein in alfalfa is converted to non-protein nitrogen
(urea) and/or nitrates, which are toxic to horses. The body
produces ammonia in an effort to flush excess protein, urea,
and nitrates. This process is very hard on the kidneys, not
to mention the potential for respiratory problems from inhalation
of the ammonia fumes. Healthy urine should be clear, not cloudy
and foul smelling.
Dehydration
When the body uses excess protein for energy, the nitrogen
end of the protein strand is cut off separating the nitrogen
from the amino acids. The amino acids are used to carry on necessary
metabolic functions, while the excess nitrogen forms urea (non-protein
nitrogen), which is removed from the bloodstream by the kidneys
as was discussed above. It is a higher priority for the horse
to flush the toxic ammonia that was produced in this process
as compared to holding onto water for hydration of the muscles.
The horse will drink lots of water, urinating more frequently,
leading to dehydration, especially in hot weather or while under
more strenuous exercise. These horses typically have thick,
foamy sweat which does not cool them as effectively as the thin,
watery sweat, so they end up sweating more which dehydrates
the body further.
Scratches
Horses who eat a diet high in protein, tend to have scratches
on their pasterns and legs. Simply removing alfalfa from the
diet often clears up the scratches.
Increased chance of disease
Because alfalfa is so high in protein, which the body digests
as acid, the horse is more likely to have decreased resistance
to parasites and diseases. Too much acid in the intestines will
cause the good gut bacteria to go into dormancy and even die,
while the bad bacteria actually thrive in an acid environment.
The good bacteria in the gut are actually the body's first line
of defense against disease. Parasite, bacterial, and viral infections
all proliferate in an acidic body, plus with the population
of the beneficial gut bacteria being decreased, this gives the
infection(s) more ability to survive and overpower the body's
immune system.
Arthritis
As discussed briefly earlier in this article, the body will
pull minerals from the bones, ligaments, and tendons when placed
in an over-acid condition. The high protein diet triggers the
body to go into emergency mode to keep the body alkaline, which
in turn keeps the heart beating and the organs functioning.
The body places a higher priority on the heart and organs over
that of the structure. Minerals are therefore pulled from the
structure weakening ligaments and tendons, and the demineralized
bones become like styro-foam over time. As the ligaments are
demineralized, you may hear clicking in the joints, the horse
may develop a sore back as the muscles are having to do more
work that the ligaments should be doing. Over time, the body
will try to stabilize the joints by building up calcium deposits,
and you will see osselets, spavins, navicular and the like.
Permanent unsoundness due to structural demineralization is
only a matter of time, although a lower protein diet consisting
of mostly top quality grass hay and proper mineral support can
help prevent this scenario and sometimes even reverse the damage
of arthritis.
Dr. Karen Hayes, D.V.M., who wrote Modern Horse Breeding, states,
"Under no circumstance should the amount of alfalfa in your
horse's diet ever exceed 40% (by weight). Any more than that
and you are risking the perils of excess protein and excess
calcium, both of which can do some unbelievable damage. If your
horse's ration consists of 100% alfalfa, he may look healthy,
but that does not mean it isn't taxing his system."
Again and again, balance, balance, balance, is the key to feeding
your horse promoting true health from the inside out. This applies
to protein balance as well. We must feed enough protein to maintain
condition and integrity of the entire system as proteins are
necessary for enzyme and hormone production and function, but
we must be vigilant and feed a diet that is no higher than 12%
total protein. Our horses may look shiny and healthy for a period
of time, but all the while silent destruction is taking place.
I have personally noticed that horses who are fed a high protein
diet do not tend to break down until they are about 7-9 years
of age. It took time for these unsoundnesses to come to the
surface, but the damage was stressing the body on a daily basis
behind the scenes until the stress finally weakened the body
enough for the symptoms to appear. Symptoms of poor attitude,
structural and muscular dysfunctions, poor coat condition, kidney
stress, etc. can all be due to major protein imbalances. Feeding
no more than 20% alfalfa and a low protein grain ration along
with proper minerals will definitely set your horse up for success
and promote total health of the whole body, not just increased
performance. A horse that feels good will be easier to work
with, will perform better, and experience a longer life. I believe
it's worth it to spend a little more time locating good quality
hay that provides around 12% protein. You will be amazed by
the results!