Protein for horses revisited

I need to update my view on protein sources to account for the deception many protein supplement manufacturers are creating at the expense of helping our horses. Deception is a strong word but applies to their manipulation of ingredients while maintaining the appearance of the bag it comes in as well as the look of the supplement itself. But before I actually describe their art of deception, I want to do a quick review of protein.

Proteins and their building blocks of amino acids

Protein is a word that describes a very large molecule that is made up of smaller molecules called amino acids.  A good way to look at this is to think of a protein like a word and an amino acid as a letter.  When you text a message you put together letters in the right amounts and in the right order to make a word.  The blueprint in your DNA does the same thing by putting together the amino acids in the right amounts and in the right order to make a protein.  The proteins that are made do a lot of different things in the body including connective tissue (muscle, tendons, ligaments), neurotransmitters (dopamine, acetylcholine), enzymes (protease, amylase), hormones (insulin, leptin), immune modulators (antigens, immunoglobulins) and hard tissues (hooves, hair).  

There are between 1 and 3 Billion proteins per cell.  There are only 20 amino acids that make all of these proteins.  While this seems impossible, think that there are only 26 letters in the alphabet that make up all the words in a dictionary.  But if one letter is missing then there are a lot of words that will not be made.  No “W” then no “tomorroW.”  Likewise if one amino acid is missing then there are a lot of proteins than cannot be made.  This is why it is incredibly important to know the ingredients and not just the % of “protein” in the supplement.  Different proteins supply different amino acids.  Remember this when I talk of the deception later.

The Protein Recycling Program and the Chronic Deficiency of Proteins

With the exception of hair and hoof, proteins in the body don’t last long.  On average all proteins are broken down within 2 to 4 days into their amino acid parts and these are reassembled through a sophisticated recycling program to preserve the amino acids.  Horses in the wild have access to a variety of protein sources throughout the growing season where they stock up on proteins.  But in the winter, attrition occurs as the horse loses some proteins.  For example a horse does not recycle the amino acids used to make the hoof or hair.  These are permanently lost as they are lost to the environment.  They then need replacing.

In a normal world the horse would maintain the amount of protein to remain healthy by conserving and recycling amino acids and ingesting enough to replace lost material.  However, in the current modern state of keeping horses, there are a number of reasons why horses are becoming chronically deficient.  I will list them here and if some of these don’t make sense then return to my previous blogs for a further explanation.

1) Carbohydrate dependency – This is the leading cause of protein loss.  Let’s look at the normal horse eating only what is available outside at the time of the year he is eating.  When sugar (glucose, fructose) is available in grains, seeds, fruit like apples, carrots and lush growing pastures, the horse uses it for cell fuel.  But glucose is not an efficient fuel and the cell actually becomes tired because the mitochondria become exhausted converting it into energy.  The result of this in most horses is adding body fat.  This is OK in late summer and autumn because the message the body is receiving from sugar being available is that winter is coming.  But there is little sugar available in the winter which causes the horse to convert to using body fat (ketones) as the cell fuel.  Ketones are a more efficient fuel meaning the cell gets a lot more energy from ketones than from glucose.  The result of this is loss of body fat (good) and a rest for the mitochondria (also good).

When a horse is fed sugar every day of the year (grain, treats), the mitochondria within the cell become exhausted which in turn causes the cells to die.  As they die, they no longer do their job and illness and soundness issues appear.  For example, mitochondrial dysfunction (death) has now been determined to be a primary cause of tendon rupture in humans.  How does this happen?  When the cell becomes weak the brain thinks the body is dying.  The brain determines that the cells need more fuel so it converts proteins into sugars through a process called gluconeogenesis.  The result is a shrinking top line, a poor hair coat, poor hoof condition, and an assortment of diseases and lamenesses.

2) Lectins – these are plant proteins made by plants to make ill and even kill predators such as humans and horses that are eating the plant babies (seeds).  You can read more about this but in essence, these plant proteins can disrupt the tight junctions of the gut lining causing leaking gut syndrome.  They can also disrupt hormone communication by mimicking hormones making that hormone ineffective.  One such lectin called wheat germ agglutinin mimics insulin preventing the real insulin from delivering glucose to the cell.  This leads again to cell dysfunction and cell death which in turn leads to gluconeogenesis and protein loss.

3) Grain byproducts – The plant lectins are concentrated in the outer layers of seeds.  These layers are removed from foods made for humans and then given to animals.  For example, whole grains have more lectins and therefore the wheat hulls are removed to make white wheat flour.  This creates the wheat middlings and wheat bran used in almost every commercial feed for horses.  Remember wheat germ agglutinin above?  Most Asians eat white rice as they know the outer layer called rice bran is not good to eat.  Rice bran is often found in horse feed.

4) Medicines – Proton pump inhibitors used as anti-ulcer medications raises the pH of the stomach making it less acid.  The purpose of stomach acid is to kill foreign bacteria (including the probiotics you feed) and to break apart the very large proteins into smaller pieces for digestion.  If the proteins are not adequately predigested in the stomach then they will pass out of the horse undigested.  This adds to the protein deficiency.

5) Gut microbe dysbiosis – this means that the bacteria that normally inhabit the gut are not happy.  This leads to a lot of dying or dead good bacteria and the growth of bad bacteria.  If you consider that all the food you place into the horse is there to feed the gut bacteria and NOT the horse then you will quickly understand how important it is to feed the right food.  If the gut bacteria are dying then deficiencies will occur in many nutrients because it is the gut bacteria that create the fuel that feeds the mitochondria of the cells.

6) Feeding oils – With a few exceptions (4 exceptions in humans), any oil fed to a horse such as corn, vegetable or soy bean oils will bind to the dead parts of the gut bacteria called lipopolysaccharides and together they form a devastating particle able to penetrate the gut wall.  As they appear on the inside of the horse they create a 5 alarm fire of inflammation which causes ulceration and an influx of white blood cells.  What you see as a fractious horse unhappy with being groomed, cinched or girthed, trailered or ridden.

All of these items listed above either consumes an excessively high amount of protein or prevents the absorption of the needed essential amino acids.  The result is the same: protein deficiency that is chronic when the causes go on year after year.

The Deception

Marketing is an every day part of life.  We all do it.  As a child when we wanted something from our parent we marketed using whatever facial expressions we could muster as well as pulling on every available heart string.  When we were told no we didn’t like it and we resolved to do better marketing in the future.  

As you open the magazines and look at the marketing of items made to improve our horse’s lives we see a familiar pattern.  It goes like this.  You and your horse have a problem (old, lame, sick) or COULD have a problem (colic, founder, not win).  We have a solution (product, service, food, supplement).  You, the consumer and care giver and horse trainer want to have a happy horse so you trust that the product you are about to purchase is well tested and will do no harm.  This is enforced when you see your horse actually like the product.

The deception occurs when you stop and think about what you are feeding your horses and then ask if what you are feeding is actually helping your horses.  If not, you attempt to read the ingredients to determine if the food ingredients are to be blamed.  Here is where you get stuck because, unfortunately, your efforts reveal that this is not as simple as it seems.  Not only are there long words of unfamiliar ingredients, they have changed since the last time you read the label.  This happens all the time.

The ingredient label for Progressive Nutrition’s ProAdd Ultimate from 2017.

The ingredient label for Progressive Nutrition’s ProAdd Ultimate from 2018. Note that whey has been moved far from the beginning and that other inflammatory ingredients have been added.

Today I just recommend as a protein source for horses straight soy bean meal (SBM) that is de-hulled with the oil solvent or pressure extracted and with only a flow agent added (lanolin).

I once encouraged people to purchase a protein source called ProAdd Ultimate made by Progressive Nutrition and owned by Nutrena.  When I did, the ingredients were listed in a way I thought would not be too harmful to horses.  The first few ingredients (the main ingredients listed in order of amount in the product) were something useful to the horse followed by some less useful ingredients.  Over the past year the company has changed the ingredients to such that I can no longer recommend it.  Apparently in manufacturing a product, ingredients are changed and re-ordered all the time due to economics or due to technical issues with the machines.  For example, in human food corn syrup is used to lubricate the machines and it’s removal would require retooling the machines.  For this reason corn syrup is in a lot of food manufactured for human consumption.

Soy Bean Meal – de-hulled and oil removing with solvents (OK for horse) plus a flow agent.


SBM is inexpensive and should be fed a pound a day for a horse weighing 1000 to 1400 pounds with only pasture, water, salt and hay (grass plus a flake of alfalfa).  This should be continued until the signs of protein deficiency are gone (improved top line, hair coat, hooves, resolved diseases).  After this the amount can be reduced, eliminated or given on occasion.  Think of adding SBM like a treatment as you are treating a protein deficiency.  Once the gut has restored itself to normal and protein loss minimized then the amino acid recycling program should be enough to maintain the protein levels in most horses.

PLEASE NOTE: If you are afraid of feeding SBM due to GMO, glyphosate, feminization (estrogen) or political reasons – don’t be.  There is no recorded problems with feeding SBM to horses due to these concerns and since 1973 I  have had no adverse reactions to this..   Remember that feeding SBM is only for a year or two max.    More importantly, chronic protein deficiency has been devastating to the health of the horse.  We need to fix that now and SBM (without sugar added and without grains and treats and other supplements) seems to work the best to resolve this in most horses.

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Comments 21

    1. Post

      Look at the way the SBM was made. If solvents were used this may be the issue, though it is rare. Also look for molasses added. SBM also has a flow agent like lanolin added. Maybe another brand would work.

      If it is SBM causing the hives then try whey protein. There are several sources for horses such as “Equine-whey.”

      Be sure there is some alfalfa in his diet as this will help with protein deficiencies.

  1. I think most wont read the entire article, or your 12 part blog series on nutrition, but I am on board —completely— w/ the no grain challenge… it’s worked for my horses-and one non sweater is sweating this summer. I really think it’s brilliant and challenge all horse owners to feed horses as they were intended to eat.

    1. Post

      Thanks Judy for this. Many have told me that they don’t read these because of…. well the list of reasons are long. But I understand that most don’t know how their cars work and take them to the repair shop when they break. Prevention is not really high up on the list. The same is true for themselves and their health.

      But we are all responsible for the health of our animals and we all need to invest some time and at least TRY to get it right. It is hard to do when the blitz of misinformation confuses us. We can just hope that some people will read a comment like yours and be inspired to try.

  2. Thanks again for the update. It is so darn difficult to make sense of the labels. Just trying to keep it simple! Thank you …Patrice

    1. Post
  3. Good follow up article, Doc T! As you know, I have subscribed to your philosophy of feeding (though it took me quite a while to be “all in”). I have been following your feeding outline 100% for, now, 20 days, the first 10 days as the “cleanse”, with ONLY pasture, orchard grass hay, and Himalayan salt block (well, turned out to be 17 days, since the protein source didn’t arrive on time, 😡). I have introduced the protein sources outlined below and he has been on this regimen for 3 days now:
    I did a LOT of research on protein sources, with what you wrote above as a foundation of thought. What I found (which made sense in my layman’s viewpoint) is that the best way to feed according to your outline, is to buy and feed 1/8 pound (for now–may increase to 1/4# if it is not apparent in quality muscle gain over time) HUMAN GRADE natural/natural whey protein isolate (no additives, no preservatives, no sugar/sweeteners/flavor, etc. from Lucky Vitamin online–expensive, but worth it when you consider the quality and stated bioavailability to the horse/human–yes, I use it myself), and mix with 1ounce Kosher salt, 1pound organic alfalfa pellets (from Standlee), and one ounce of organic coconut oil (from Uckele–again, very expensive, but worth it because of the Omega-3/6 ratio), as well as for palatability–he loves his meals! I chose alfalfa and coconut oil instead of the soybean meal, specifically because of the lectin and omega6 issues. I am still in the experimental phase, but so far, so good. Do you think I am on the right track? I commented here, instead of emailing you privately, because I think others who are considering this might find my questions (and your answers) useful. 😁

    1. Post

      Thanks Mary. Soybean lectins would be found in the hulls and these have been removed. The lectins of a legume (soybeans, alfalfa, peanuts) would be damaging to humans but so far they, nor any lectins, have been studied in horses and in addition, no horses to my knowledge have signs of gut inflammation from legumes. There may be a horse who reacts to alfalfa but there are usually other inflammatory causes. But your horse does not react to alfalfa so I would think that all legumes including soybeans would be OK (especially de-hulled beans).

      The Omega oils are also interesting because of the amount of human information. The 3’s being anti-inflammatory and the 6’s being inflammatory. But what makes fractionated coconut oil special is that it is a medium chain triglyceride that bypasses bacterial digestion in the human gut and advances through the gut wall for direct use as a fuel after it is converted into a ketone. I take this oil every morning and it improves cognitive function plus it staves off hunger until after noon. Remember that a healthy gut will digest cellulose into short chain fatty acids which also become ketones, myelin sheaths, cell walls and other useful fats.

      Whey protein isolate works well in humans and horses (about 94% bioavailable). If you do the math and your goal is to replace the lost protein (0.5 to 1.0 grams protein per pound of body weight) then I think you might be under-dosing. However for maintenance, ¼ pound per day may be enough when combined with pasture and alfalfa.

  4. Thank you for taking the time to explain these issues and point out the changes to the feed composition. People want to do the right thing for their horses, but in fact marketing does overwhelm many buying choices.

    1. Post
  5. Dr T…… I’ve looked at your offer and four items are in the picture. What exactly do we receive. Are these all online books, DVD’s , online only, what?
    I’m vey interested , but I can’t figure out what I’m paying for.
    Please help me understand.
    Also I see you are a dentist . Do you travel or must we drive to you with our horses?
    Sorry for so many questions.

    1. Post

      Hi dorothy – the images are to let you know that this is an online course that you can use on any device. As long as you have a browser for the internet you will be able to see the information.

      My dentistry practice covers the US but I limit my practice to the states I am licensed in unless special arrangements are made. Please contact me at 888-467-9838 and leave a message. Be sure to include the state you live in. You can also email

  6. Thank you for explaining this, I must go back & reread your other articles. So you don’t recommend the full fat soy meal? Looks like I shouldn’t be adding rice bran either – I’ve been adding it for extra fat (a cup or 2) for the older mares. Most of this year, they have been fed lucerne (alphalpha) or grassy lucerne, with occasionally a little copra meal (coconut), brewers yeast, sea weed meal, dolomite (calcium mostly) & sometimes salt. With the drought in Australia, there’s no copra meal avail & hay is getting hard to get (hopefully in a few weeks there’ll be some more lucerne, now that it’s starting to warm up). We’re in South East Queensland, so not as bad as NSW or outback Qld. Thanks Andrea 🙂

    1. Post

      Remember that in a healthy gut the cellulose of grass (and hay) is made into short chain fatty acids. This is hoe horses get their fat.

      Brewers yeast is a form of a probiotic. With all things remaining the same, try eliminating the yeast. Most people think that yeast and most probiotics are digested by the stomach acids but more research needs to be done here.

      I have no experience with dolomite which is calcium plus magnesium. I would think this would be helpful in horses fed grain (high in phosphorus) to prevent rickets and low calcium (hyper excitability).

  7. Thank you Doc T. Another fantastic update. Clear concise revisiting of important points. Is the newly recommended SBM readily available at feed stores or does it need to be special ordered? Are there any situations SBM should not be fed (particular disease state -cushings, insulin resistant, anhydrosis etc…)? Is there a particular brand of SBM yo use or to stay away from?

    1. Post

      SBM should be available almost everywhere grain is sold or milled. Avoid SBM with molasses added.

      SBM should help all these diseases. There are no contraindications although I have heard of a horse (see below or above) that gets hives from it.

      Be sure the SBM has been de-hulled and the oil extracted.

  8. Hello Doc T,

    With Winter coming would you recommend more alfalfa hay or is the alfalfa hay for more of a additive? I have older not so easy keeper horses and one is a elder thoroughbred who’s weight is always on a thin line. I just read this article because i been doing your challenge since june now and thank you for the great information update! a lot of my horses are doing well i have a warm blood who wasn’t liking the pro-add anyways so having this now is great to change him over to. (hopefully he won’t be so picky!)

    Thank You


    1. Post

      1 flake of alfalfa per day should be enough even in winter. Management helps more (bring inside, blanket, heat the water, add more grass hay, add coconut meal) if they start to really lose condition.

  9. Thanks Doc T. I’ve always been a label reader. You do have to constantly read labels as the manufacturers always change their ingredients. WE have to be in charge of our horses and our own health!

  10. Thank you for the reply, Doc! He has been on the protocol now for 21 days, and I did double the amount of everything I was feeding him over the course of the last 10 days. He didn’t lose much overall weight (if any at all), even during the “cleanse” phase, or while introducing the whey/alfalfa/coconut oil, but now that he is on what I would consider a maintenance amount, his body shape is changing positively, with a more rounded topline, especially in the hindquarters and loin area. I will wait a bit before increasing any amounts to see if the wither area continues to fill in properly, as I don’t want to overfeed and waste any benefits (or money!). He continues in his dressage work with a normal amount of energy and enthusiasm. So, so far, so good. I will keep you posted as to any changes, positive or negative.

    1. Post

As of November 2018 I will no longer reply to comments. There is just not enough time in the day! I sincerely appreciate all of your interest and am grateful for the time you take to comment here. Doc T

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