So, I've heard several people voice different opinions about what makes a horse "hot". Disclaimer: I fully believe that too much of nearly anything can cause an unused build up of energy that can be "spent" by any horse in a manner we could consider "hot" behavior. I've recently been discussing feed options with a boarder and started pondering this...
The calories from protein and sugars and starches are used differently by a horse, and stored differently. From research (and NOT wikepedia research, but university research articles, etc) and personal experience, I believe that you definitely get "hot" from high NSC feeds, particularly if you have a naturally high-strung horse. If you feed a naturally high-strung horse a feed higher in proteins/fats and lower in sugars and starches, you will have a well-fed, less hot horse.
I have repeatedly found that controlling sugars and starches is the key to decreasing the "food impact" on a horse's behavior. Proteins add energy, of course, but does not store in the body the same as sugars and starches. For more calories but less "heat", I like to add fat to the diet of horses prone to being high-strung.
I'm sure this topic has been previously discussed at length elsewhere, but just thought I'd ask this specific question:
Just out of curiosity, what is your opinion regarding this? Please share where you got your information (research, experience, trainer, trusted confident, veterinarian, etc...).