What breed are your birds? Cornish X need a special high-protein feed. But most "dual purpose" birds it doesn't matter so much.
I feed all my dual purpose birds (Buff Orpingtons) the same feed -- layer feed. I start chicks on it too -- they eat the tiny bits, the big birds eat the big bits. Makes things much easier.
A lot of people might think this is not the "correct" thing to do, but the layer feed has plenty of protein etc in it for the roosters too. Since I butcher my roosters at 6 months, I don't worry that they might be getting too much calcium. I also free-range my birds, so they are getting lots of other food (seeds, bugs, greens) in addition to their layer feed. In 3 years, I've never had any problems with my layers or my roosters fattening up.
The only time I changed my feed was for the last 2 months for my heritage turkeys -- they got a higher protein feed to fatten them for Thanksgiving.