In the FF thread someone noticed their chicks going under the heat lamp after eating FF so maybe the FF does result in higher heat requirement. Not sure about the water theory. When I switched my meaties to FF, the water that did not go into the waterer was going into the feed - but I did not measure the exact amounts. Another theory - maybe the CX do not burn as much energy to digest FF compared to dry. CX are know to generate a lot of heat. If the unfermented food that causes them to generate heat, the FF birds would need more external heat (heat lamp).