To understand protein and protein needs, it's important to know what protein is.
Protein is the name given to a complex molecule that is a combination of smaller parts called amino acids, which are hooked together like the cars of a train. Amino acids are called the "building blocks" of proteins.
There are some 22 different kinds of amino acids that exist naturally and they may many different shapes and structures. Therefore, many different kinds of proteins can be made from different combinations of amino acids.
The living body requires protein for every function, organ and tissue in the body, even bone. Protein comprises 90% of the dry weight of the living body in animals, and humans, whether cold blooded or warm blooded. Protein is the basis for living tissues and there are definite requirements that need to be met daily to keep the body healthy. Shorting the body of daily protein causes increases of carbohydrate cravings, bloat and swelling, sluggishness, loss of fertility and productiveness, poor hoof and hair coat, poor behavior and a host of other common compromises. Hormones and enzymes are made of protein and so are also severely compromised in states of protein deficiency.
The modern complication of meeting protein needs has to do with the non essential category of protein, in that it is well known that certain herbicides and likely many other environmental toxins can interfere with the internal production of both hormones and amino acids. A good example is that of tyrosine being compromised in production by low levels of herbicides, so that hormones that use tyrosine like thyroid hormone and neurotransmitters in the brain are deficient. Thus, exposure to low levels of herbicides can cause hypothyroidism and brain dysfunction like depression and even mental illness. As crazy as it seems, herbicides are given to people with a genetic defect called tyrosinemia in Europe, because they produce too much tyrosine. The herbicides are given intravenously in a hospital setting. And statistics in the US show continuous lowering of basal metabolism and basal temperatures in a direct proportion over the last few decades as the levels of herbicides residues rise in the environment, tainting out food, water, air and soils.
When the body is compromised in its ability to manufacture internally the amounts of non essential amino acids it needs, then all the proteins that need those amino acids are also deficient, and with increasingly greater compromise, more and more of the non essential amino acids are now shifted into the essential category and must be supplied by food.
Bottom line, as the world gets more and more toxic, we need more and more quantities of protein and also those sources of protein need to be of higher quality to supply the increasing number of compromises our bodies are suffering. Meat protein is considered to be the highest quality protein because it supplies what the living animal body needs to essentially make more meat. Plant sources of protein are not complete, in that it does not supply all the necessary amino acids needed today. More and more, people and horses need more quantity and quality of protein in the diet because of the reasons explained above. What worked well in decades gone by, will not be adequate in the future. The world has changed dramatically.
Here we run into another problem with learning about protein. The conventional and standard method of testing foods and feeds is to run a simple test for all nitrogen containing compounds, because all protein does contain nitrogen. However, the "fly in the ointment" here is the not all nitrogen containing compounds are real protein. Nitrates, nitrites and many other compounds also contain nitrogen but they are not proteins. So we have to be careful when we are talking about the two categories of tested protein.
The total amount of all compounds that contain nitrogen. This is a very old term in industry and not very accurate either. In testing feeds, we really cannot say how much actual protein is in there based on this one number, because all that tests with nitrogen is not protein, remember? "All that glitters is not gold"! A feed or food can test very high for total or crude protein and very low in actual protein, and even be toxic for nitrates or nitrites. Remember the massive pet deaths from the melamine laced pet foods several years ago? Melamine is a well known plastic and toxic to ingest. Chinese manufacturers added waste melamine from their plastics factories to pet foods because it artificially increased the nitrogen levels in the pet foods, fooling our USDA into thinking that the correct level of protein was really there. "Bum numbers"...that is what CP / TP really is. You cannot get relevant information from it to calculate the nutrition you need without doing more testing to get the real picture. All that glitters is not gold!
Non digestible protein - that is real protein but not able to be digested by the body who eats it. A good example is chicken feathers, added to pet foods to again, artificially and cheaply hoist the protein numbers on the can or bag but most dog and cat owners are now aware that their pets cannot digest that kind of protein. Again, more Bum Numbers! So looking at the ingredients in a feed, do we really know just how much protein that feed supplies if we see "chicken parts or chicken meal" or some such on the bag or can? Hardly. We do not know just how much feather meal is in there. And we do no know how much of the rest of the feed is actually "digestible" protein.
Digestible protein is exactly that, the body is able to correctly and completely digest the protein down to the amino acids to then be able to reassemble those amino acids into the body itself.
If the protein is really totally digestible, then the enzymes are not wasted by being locked up in incomplete digestion reactions instead of being able to be recycled into the next reaction as enzymes are supposed to do. This causes additional hardship on the body because it takes out active needed enzymes, on top of wasting valuable digestive efficiency trying to digest something that it cannot do. In horses, the telltale sign of poor digestibility of the feeds being given is the swollen, distended and large hay belly. Since the bulk quantity of foodstuffs are supposed to be digested and nutrients absorbed over the 100 or so feet of intestine, the sheer quantity of foodstuffs is supposed to be reduced as it enters the lower intestine. If the digestibility is poor, the quantity does not reduce in size because nutrients cannot be absorbed and the belly stays large. The horse with a hay belly can also be actually starving nutritionally, because they cannot absorb and utilize the feed given. And the sad part is that many people will actually think that the horse is fat when the opposite is really true.
Digestible protein is exactly that, the body is able to correctly and completely digest the protein down to the amino acids to then be able to reassemble those amino acids into the body itself.
If the protein is really totally digestible, then the enzymes are not wasted by being locked up in incomplete digestion reactions instead of being able to be recycled into the next reaction as enzymes are supposed to do. This causes additional hardship on the body because it takes out active needed enzymes, on top of wasting valuable digestive efficiency trying to digest something that it cannot do. In horses, the telltale sign of poor digestibility of the feeds being given is the swollen, distended and large hay belly. Since the bulk quantity of foodstuffs are supposed to be digested and nutrients absorbed over the 100 or so feet of intestine, the sheer quantity of foodstuffs is supposed to be reduced as it enters the lower intestine. If the digestibility is poor, the quantity does not reduce in size because nutrients cannot be absorbed and the belly stays large. The horse with a hay belly can also be actually starving nutritionally, because they cannot absorb and utilize the feed given. And the sad part is that many people will actually think that the horse is fat when the opposite is really true.
Digestibility of food is also dependent on the functionality digestive enzymes that need specific minerals to activate them. Mineral deficient animals with have poor quality enzymes.
Determining the digestibility of a food source is very difficult and fully dependent upon the animal in question, his ability to product effective enzymes, toxic body burden of compromising chemicals, age, etc. So each individual animal can be different. Each food source can be different as well, depending on where and how it is grown...hay is not hay, oats are not oats etc.
And setting up experiments to determine the digestibility of a specific food source is nearly impossible based upon our technology today. We now know that there is a greater amount of bacterial DNA in any body than the essential body itself, and this will complicate our studies as well, because these organisms take nutrition for themselves.
In addition, all animals do not exist on a single food source, so setting up a diet to measure uptake of nutrition of a single food source, to measure digestibility will cause ill health to the individual. Nutritionists continually argue and disagree about the levels of digestibility, and the band plays on...
Different sources of ingredients in feeds have different qualities of protein. The quality of a protein source is determined by the amino acid profile of the feed, meaning that the higher the levels of the essential amino acids that a feed source contains, the better quality it is. The very best is red meat, because red meat supplies all of the amino acids and proteins that a mammal would need to essentially reproduce the red meat that it, itself, consists of. But horses do not eat meat normally, so we have to look at the quality of the amino acid profile in plant sources.
The standard for the quality of protein sources is red meat. Legumes are the highest quality source of protein in the plant world, but not as high as red meat, followed closely by the oilseed meals. The problem with legumes, however, like soybean meal, alfalfa and even split peas, is that they also contain at least 5 known compounds that exist naturally in all legumes, that interfere with the binding of iodine to tyrosine when the body manufactures thyroid hormone. This is known to cause hypothyroidism, and legumes were given the name of "goitrogens" some 100 years ago, because of the observed thyroid compromise in animals and humans fed quantities of legumes.
Recent research has shown that simply compromising the manufacture of thyroid hormone does not, in itself, cause a certain goiter. Other compounds independent of that biochemical pathway have been found to be responsible. We have not, as of this writing, identified compounds in legumes that cause goiters, however they may be there. Still, with the exponential increase in environmental chemicals, some 80,000 just since WW2 that are known to disrupt the endocrine system and thyroid taking the biggest hit of any organ or tissue in the body, the use of legumes in the diet of both humans and animals has been dramatically decreased. What was tolerated in years gone by, is not well tolerated in today's world.
Oilseed meals of linseed, canola, hemp etc are well tolerated in horses and also provide nice levels of essential fatty acids as well. Linseed meal is the processed, oil extracted meal from flax, however using whole flax meal at the levels needed for protein supplementation can cause colic, laminitis and hormone interference, as flax oil is known to be estrogenic. Whole flax, fed at levels needed for proper protein supplementation, supplies too much of the estrogenic oil. That is why linseed meal is safe and has been used in horse feed for over 100 years.
Next on the list of protein sources are the grains; oats, barley and the like. Being seeds, they contain higher levels of the essential amino acids needed for potential growth of a new plant, but they are only about 1/3 to 1/2 as high in quality protein as the oilseed meals listed above. They are fed mainly as an energy source because they are much higher in carbohydrates.
Last on the list of quality protein sources are fiber products like hay, straw, corn cobs, soybean hulls, etc. The quality protein in hay is found mainly in the seed heads, but if there are no seed heads and only leaf, then the quality of protein goes down. There are no seed heads in the other fiber sources, so the quality of protein is very low in those.
NRC recommendation for crude protein per day is 1.5 lbs.
Grass hay contains nitrates, nitrites and other non-protein nitrogenous compounds naturally and especially from fertilizers, that artificially elevate crude protein levels in standard testing, making the hay look much better in protein than it actually is.
For this reason, Vita Royal chooses to use digestible protein calculations for hay, for better accuracy. Digestible protein for grass hay is 2% to 3%, and the actual quality of that will depend on the amount of seed heads in it. Digestibility is a separate issue from quality.
20 lbs. of grass hay provides 0.5 lb. of digestible protein, and figuring that number in to the crude protein needed per day of 1.5 lbs., approximately 1.0 lb. of crude protein is still required from supplemental feed per day.
Hay-only diets therefore, only provide about 1/3 of the actual protein needed per day, and often that is of poor quality form too.
Researching and evaluating both top performance and sick horses at both ends of the spectrum for nearly 40 years; incorporating mineral, nutritional and hormonal testing; has given me a unique perspective on the protein needs of horses, including the increasing need for more protein in the diet of all animals and humans, due to the biochemical compromises of manufacturing the non essential animo acids, and growing levels of environmental toxins. I have been incorporating that research into products and feeds since 1972, when I first formulated Hi Pro. Since that time, I have perfected the formula as more raw materials of good quality became commercially available, and I will continue to do so in the future. So now, I invite you to enjoy feeding your horses the fruits of my labors, and see your horses bloom as they should.