One does wonder what that "protein" is.I think the big problem here is that we don't know which precise breed of chicken we're talking about. I favor heritage breeds which don't produce as many eggs per year and are much more self-sufficient. If we're talking about one of the new sex-linked birds that are focused on maximum egg output then those were definitely built to feed on processed food for their short brutal lives.
Of course since there was never such a thing as a pellet tree to feed the poultry from, what goes into to those pellets is basically anything the factory can get away with unless the government wants to spend enough money to catch them. We can trust the feed factories, after all these are the same folks who brought us mad cow disease. Pretty much meaning that those male chicks that get sorted out most likely end right back up in the feed you are giving your hens.
Remember, you can trust the marketing blurb on the package, when was the last time an advertiser lied to you?