That's true; I think it depends on how much variety and space they have when free ranging.free ranging they usually get plenty of protein from bugs worms etc, mine are doing fine and on 3*1 scratch grains without mollassass , they don't seem to care for any of the so called chicken feeds. There is a difference though free ranged have access to what they naturally eat, cooped does not and you have feed them the other type mainly
I have heard some advise still having regular chicken feed available, in case they can't meet all of their needs free ranging, but this may apply to hens more than roosters.