Why we feed a grain free diet

We first learned of this way of feeding a grain free diet from Dr Geoff Tucker at a seminar in August 2019, shortly after our move to Aiken. Emily read all of the following blog posts, talked to many friends and neighbours, and decided to try it out with Betty, her hardier type senior mare who had never been able to develop a good top line. Eventually she moved Pisgah, her hothouse flower with multiple medical issues, to a modified version of this diet (due to EPSM/PSSM, Pisgah needs the added fat).

https://theequinepractice.com/travels-with-doc-t/horse-nutrition/

The important posts:
https://theequinepractice.com/feeding-the-horse-as-simple-as-1-2-3/
https://theequinepractice.com/protein-for-horses-revisited/

Emily’s cliff notes::
Start with a 2 week 'cleanse': Eliminate ALL feed and treats: just hay/pasture/water/salt. This helps the horse's body to eliminate inflammation and be able to use the protein in the soybean meal.
After the 'cleanse', the diet is limited to water, salt (free choice loose is preferred), pasture, hay, soybean meal, and alfalfa pellets if needed. NO TREATS! We use hay cubes or large pellets as treats.
This diet works well for my metabolically normal horse (pasture + 1 cup SBM per day), but not for my PSSM horse (pasture + SBM + alfalfa pellets + Renew Gold + camellina oil), as she needs fat to maintain muscle on her top line. I am slowly eliminating supplements by not repurchasing as they run out. He does say you can do alfalfa pellets and salt during the cleanse if your horse is in a boarding environment, etc where it's better for them to be fed 'meals' with the other horses.

https://theequinepractice.com/why-horses-should-not-be-fed-grain/
'What is the 2 week no-grain challenge?
Get a calendar and mark the start date and record all your observations about the horse including physical and behavioral. Then remove all grain from the diet of the horse (no weaning is necessary – just stop all at once). This includes corn, oats, barley, wheat, wheat middlings, sugar beet pulp, rice and wheat bran, oat hulls, etc. Feed only water, pure rock salt (no additives), grass, and hay (grass hay and legumes such as alfalfa). That’s it.
Your horse may go through a behavior withdrawal at feeding time but this will pass in about 2 days. If you insist on offering a timed feeding (again, they are continuous eaters so the concept of breakfast or dinner makes no sense to them), then offer a “meal” of a few alfalfa cubes either dry or soaked in water.
When I say just grass, hay, salt, and water, I did not mean that treats, candy, carrots, or sugar cubes are OK. Remove all supplements too because most of them have grain of some sort. Remove the red mineral salt block (corn syrup and molasses). Just grass, hay, pure salt, and water for 2 weeks. Record your observations. Get others to help you observe without telling them what is going on. Make your own decision on weather or not to feed grain to your horse. The challenge costs you nothing and I have no agenda in you doing this other than for you to see for yourself the changes your horses go through.'

From The Horse’s Advocate Facebook group:
[Geoff Tucker DVM posted a helpful three-post reply within one of the threads below a few days ago. I thought it would be worth posting here as its own post because I suspect many people didn’t see it buried within the thread. So I’m copying and pasting it here:]
part 1 - What an interesting thread! So many views and, like in anything, so many twists on what was originally said. But there is more…. So let me try to straighten things out here.
This is a diet based on feeding a horse like all hind gut fermenting animals (horses, asses, zebras, tapirs & rhinoceroses are the ONLY animals I know with similar digestion). They graze on a variety of ground plants which changes with location and season. In most horse environments today, horses are fed a very few varieties of ground plants. I call pastures today “mono-grass pastures: though some are filled with weeds. But they are certainly NOT a wild variety that the horse can leave or seek out at will as migration of horses has been stopped with fencing.
To supplement horses in winter, they are fed last summer’s pasture in the form of hay which is very limited in variety. They are usually a “mono-hay” or a mix of 2 types with one a grass and the other a legume. They are often labeled as good or poor hay but with all, there is a starch component that is usually higher than dormant winter pasture. However, if the grass in the pasture is of a winter resistant variety (ex, winter rye) then the sugar (starch) content will be high throughout the winter.
While many are concerned with genetic modifications, it is usually unknown that many of the seeds used for pasture have been modified for increased production in cattle. In other words some pastures are higher in sugar for the production of fatter cattle. In my latest blog about vitamin deficiencies in pasture and hay I discuss the replacement of minerals by all good farmers who want to stay in business. I also revisit chelation of minerals and the need for amino acids to do this. My opinion is that any mineral deficiency is really a lack of protein to carry into the body the minerals and NOT a lack of minerals in pasture and hay. However, I also remind horse owners of their responsibility to not just be the stewards of the horses but of the land they graze on. I never hear of horse owners taking soil samples for analysis and then adding back minerals to promote the health of the soil microbiome. Yes, the soil has that just like out gut!
Protein is added to the horse’s diet due to the lack of intake of ALL essential amino acids in the mono-grass diets. Adding alfalfa does not add them and I have NEVER called this an “alfalfa diet.” I have suggested to those who love alfalfa to keep it while those who avoid alfalfa can continue to do so. Whichever way you want to go is not only OK but this discussion avoids the REAL PROBLEM. We want to limit the amount of sugar in the form of starch a horse eats daily every day of the year. This mimics how it is in winter versus summer.
part 2 - Now to give you some science - - - - - Insulin is the hormone that takes sugars (glucose from starch and fructose from anything sweet you feed such as apples, molasses, corn syrup) to the areas that require sugar to either operate currently (all cells) or later (glycogen in the muscles and liver). If there is excess sugar then the insulin is “resisted” by the cells so the sugar is taken to the adipose tissue (body fat) and converted into more adipose tissue. Remember that if you eat a candy bar it will add to your body fat because sugar and fat are made of the same 3 elements - carbon, hydrogen and oxygen. PLEASE REMEMBER THIS.
Insulin is the bully on the playground and as long as it is circulating it prevents the hormone glucagon from doing its job. Glucagon takes adipose tissue and removes it sending it to the liver to be converted into ketone bodies (KB’s) which is the premium fuel for the cells. Glucose as a fuel is quick to use but has 20 times LESS energy than a ketone body and produces pollution called free radicals. KB’s do not produce free radicals. It is high grade fuel for the Ferrari called the cell mitochondria.
The ratio of Insulin to Glucagon is called the I:G ratio. When there is more Insulin than Glucagon, the ratio is greater than 1:1. In the standard American diet, the I:G ratio is 4:1. This alone is the cause of obesity and metabolic syndrome in humans and I suggest it is the same for our horses and other animals we feed. If we feed more starch filled food to our horses then the I:G ratio will remain greater than 1:1 and body fat will be added. In humans, when the total grams of sugar (carbohydrates) eaten per day is restricted to 50g then the I:G ratio dips to 0.8:1 This is where fat loss occurs because glucagon can now do its job of removing body fat. The bully Insulin is out of the picture because there is less sugar than is needed for the body to operate.
Horses that are well muscled and are athletes can consume more sugar (grain and hay) because it is consumed in their athletic activities. This is the ONLY reason grain was created for food in horses because the plow horses were not getting enough sugar to replace their glycogen stores. In ALL animals, the first order of the day is to replace glycogen then to supply energy to the cells then to add body fat for the upcoming winter.
part 3 of 3 - Finally, I will address why soybean meal (SBM) is added to horse diets and why it doesn’t work in some horses. SBM is added because most horses are deficient in the amino acids to maintain their connective tissue (lost top lines, extended abdomen, strained or broken ligaments and tendons), the integument (hair coat, skin, hooves), neurotransmitters (Cushing’s disease or a dopamine deficiency), immune system (allergies, parasite resistance) and enzymes (digestion and all metabolic processes including absorption of most minerals). This deficiency has 2 causes. The first is lack of all essential amino acids in the diet and the second is the conversion of amino acids into sugar. Amino acids are made of carbon, hydrogen, oxygen and nitrogen (plus 3 have sulfur). The nitrogen is removed leaving C H and O which are the elements of sugar (remember from above?). The conversion of amino acids into sugar is caused by mitochondrial exhaustion as the result of taking in more sugar than is needed in a day for every day of the year (see my blogs or take the nutrition course to fully understand this concept).
Now for the reason why adding SBM to some horses causes a problem. It is the I:G ratio. When protein is added to a diet where the I:G ratio is 0.8:1, the ratio remains at 0.8:1 and the protein is used to build the body. But when the same amount of protein is added to a ratio of 4:1 then the insulin actually spikes causing a ratio of 70:1! The protein is actually converted into sugar! This is why when you eat a steak AND a sweet potato with brown sugar butter AND the chocolate cake you only get fatter!
For horses with insulin issues (insulin resistance, laminitis, metabolic syndrome) adding SBM without removing the hidden sugars in the hay and pasture will not help the horse. However when horse owners see the body fat loss with the underlying severe muscle loss, the knee jerk reaction is to add back the sugar to cover up the skeleton. Adding sugar will NEVER add muscle or improve the hooves or repair the neurodegeneration causing Cushing’s disease. It will only cover up things.
I am not sure what the cause of head shaking is but while this is a horrible problem for horses, I’m not sure that it can be connected to SBM. Rather, I would add head shaking to the list of diseases we now see that were NOT in the vet text books in the 1980’s. You don’t need special blood tests to see head shaking, DSLD (dropped fetlocks), EOTRH (incisor disease and loss), fractured cheek teeth, kissing spine, white line disease, an epidemic of suspensory breakdown and a huge increase of laminitis and Cushing’s disease in anything other than ponies. None of these were in my text books at Cornell. And the only thing to happen to horses since then is the abundance and availability of grain plus the enormous amount of supplements. I would also add the reduction of pasture area and the development of "improved" grass seed.
The only diet I am suggesting here is the removal of ALL inflammatory ingredients and the replacement of lost amino acids from a naturally grown plant. While there are a few with genetic changes such as EPSM (inability to store glucose in glycogen properly), I can’t see a reason why this diet shouldn’t work for every horse. The “secret” is in reducing the sugar intake to never exceed the needs so glucagon can do its job.