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)

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.

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.

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.

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.

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.

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.

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!