It makes logical sense that a high carb food would produce more heat in digestion than a low carb food, but whether it’s a noticeable/useful difference you’d need to see some actual research on.
That being said, my flock gets a little corn now and then as a snack, and full size birds swallow it no problem.
There's some recent studies suggesting high fat foods are beneficial in hot summer months because of the way they are converted to energy by the body as compared to high carb foods like corn, which are exothermic (as in, heat is generated by the process) - its an area of feed science being researched now. I've not read enough to have an opinion of value, or even a comfortable grasp on the theory - I'm simply aware that its out there.
I'm in the nutritionally balanced diet, all the time, camp and dislike "routine suppliments", whether it be corn, cracked corn, boss, bsfl, scratch, or something else because just a tiny amount, routinely, can negatively impact the nutritionally balanced diet I'm trying to offer - more when the base diet is as borderline as the typical layer feed. Add the fact that I already have only limited control over my bird's feeding as they free range acres of mixed pastures all day, and its one more variable than I'm comfortable adding to the mix.
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Not related to your comment, I have yet to see a home made chicken feed recipe on a slick Youtube video or a fancy web page which is nutritionally superior to what I can buy from the local mill, or what was being published in Farmer's Almanacs of the (19)20s, 30s, 40s, 50s - at a time when they openly admitted that components of the feed were providing important nutrients, they simply had no idea what they were.
In the case of Garden Bett's no corn, no soy recipe, while I've not corrected for "as fed" (which will make most of these numbers *worse*!), her feed profile looks like this:
15.08% Protein (this will drop under 14%, as fed!), 8.72% fiber (not fantastic, not optimum, but not as bad as the rest of her formulation), 14.75% fat (I have no words), Calcium and Phosphorus are fine (with free choice oyster or similar), I've not looked at vitamins or trace minerals, and the amino acid profile (which will decrease when corrected for "as fed") is 0.3% Methionine, 0.57% Lysine, 0.53% Threonine, 0.21% Tryptophan (the four most significant limiting amino acids in a typical poultry diet).
For reference, numerous sources (UGA, NRCS, USDA, etc) put targets for those (age and breed dependent) at 0.4-0.6, 0.8-1.1, 0.6-0.8, 0.2-0.3 (respectively).
In short, she may know how to make a Youtube following, but she doesn't know how to make a chicken feed.