I agree that any act of digestion will raise body temp, and I, by no means, meant to not feed them. I’ve seen corn (dried mentioned more than fresh or canned), peas and scratch grains consistently and specifically mentioned in several research resources. Grasses, foraging and low sugar choices are better as they won’t raise the body temperature, should I say, "as much" as peas and corn. I was just sharing what I have found in almost everything I have read. I appreciate your input as we all have different experiences and knowledge from which to learn.Anything they digest will raise their body temperature. There is nothing special about peas and corn that would make them unusually bad or good in that respect.
Normal chicken feed raises their body temperature when they digest it too, but of course starving the chickens (nothing to digest) is not the solution either. Just provide reasonable options, and let the chickens decide how much of what to eat. (Reasonable options would mean constant access to normal chicken food and plain water, in addition to whatever frozen things you feel like offering.)