Does Feed Make a Horse Hot?

“…my horse is hot.”
“…I cannot feed my horse hot feeds.”
“…bad sugars makes my horse hot.”
“…molasses makes my horse hot.”
“…do you have a feed that will calm my hot horse?”

During my youth I recall the “grain makes them hot” declaration which paralleled a similar parental contention: “No more candy, it makes you hyper!”

An allergist in the early 70s was the apparent first who suggested that certain foods needed to be eliminated from children’s diets to reduce hyperactivity. Since that decree, multiple scientific studies were conducted with children and sugar and the general conclusion was that sugar does not influence a kid’s behavior. One interesting observation was that most of the anecdotal sugar-high claims were often associated with a celebratory occasions, such as holidays, birthdays, gathering of kids, etc. where children are inherently more excitable.

The bottom line is that no experimentally-sound study with horses has demonstrated that feeding grains/molasses or any high sources of sugars and starches will elicit a “sugar high.” There are a plethora of observations and individual experiences that will disagree with these studies. And that’s the issue, its testimonials versus sound science that can be tested and repeated. Is there the possibility that some sort of biological change could have an influence? Yes, but that biological reasoning for now is only a hypothesis and is not supported by known science.

Starches and sugars are digestively processed to glucose, a simple 6-carbon sugar that circulates in the blood with normal minimums and maximums. Blood glucose is one of the most regulated components of body-systems with two hormones, insulin and glucagon, that have the responsibility to normalize the blood glucose levels. If a body function requires energy, then blood glucose is a first responder for fuel. If there is not enough blood glucose, the body will mobilize and metabolize storage forms to increase the blood glucose levels. If there is an excess of blood glucose that is not needed, then the body metabolizes the six-carbon sugar to stored form. That stored form could be to replenish glycogen stores or, if exercise is not part of the picture, then it goes to stored fat.

Nutritional management, a phrase I have used often over three decades, is critical and can have a positive influence in the rate in which starch/sugar are digested and absorbed. Horses are managed and used much differently – digestively and socially – than how they are designed. That is why my experience points to a multitude of other reasonable explanations for horses that are at the higher spectrum of energy or have excitable reactions to their surroundings.

  • Are there existing or new vices or other behavior? What changes have preceded the behavior?
  • Are there changes in the environment, such as stall change, new/loss stable mate, feeding time, changes in bedding, changes in work schedule or conditions?
  • Has the horse been idle, stalled for long periods, or gained/lost weight or muscle tone?
  • Are there changes in body condition score? Does it take more effort to cinch at the usual strap mark (ie. gained weight)?
  • Are adequate long-stem fiber sources being fed? Long-stem fiber promotes chewing, more saliva, thus more buffer as food propels through the gut system.
  • Are there long intervals between feedings that contribute to hours of “empty-gut syndrome”?
  • Are there changes in downtime between feedings? Horses’ guts are designed to consume small amounts of food over a long periods of time.
  • Is there adequate daily turnout time? Not an hour or two, but hours per day even if there’s rain or snow.
  • Does the horse’s hyperactivity occur only during riding sessions? Is the rider inexperienced and lack balanced seat/bit control? Are there other distractions such as new equipment, etc.?

We are often asked about the sugar, starch or NSC content of the feed. It’s important to keep in mind that there isn’t a consensus or data on the amount of sugar, starch or NSC that qualifies a feed as low starch/sugar. There is also no information relative to sugar/starch dietary requirements, however for warm blooded animals, simple sugars in the blood have an important role in fueling and priming the body’s cells, thus fueling the animal. Numbers published such as 15%, 12%, etc. have no basis on how the values were determined and there is inconsistency in what those numbers actually represent.

There also appears to be confusion with the NSC acronym and the fractions of nonstructural carbohydrates represented, even though NSC is clearly stated in the most recent NRC. For these reasons, I specifically list the testing results for %starch, sugars (%ESC) and %WSC so there is no question of the nonstructural carbohydrate components.

I have worked with horses as an owner, breeder, alleged trainer (emphasis on “alleged”), farm manager, packer, professor, scientist, researcher and nutritionist and can honestly state that any horse viewed as hyperactive was able to be explained by factors other than feed. I am sure that steps on some toes, and I will also be the first to admit, “Never say never”.

“Never say Never” is an expression that is part of the scientist’s creed. Perhaps there are biological factors that have not yet surfaced that link high sugar intake with behavior. Perhaps research may demonstrate a direct link with high glucose influences on adrenaline surges or changes with neurotransmitters as some have suggested or that there are biological/neurological conditions similar to ADHD that are link directly or indirectly from a chain effect of high glucose metabolism. Of course it could also be the inverse, i.e. changes in neurotransmitters or other metabolites that cause a high glucose response. Or perhaps the horse is naturally hyper (genetics) and feeding inadequate fuel type feeds will promote lethargy behavior.

This nutritionist formulates feeds based on the gut design of animals and what they do for a “living”, thus the emphasis is always on nutritional management.