Will broilers self-select sufficient protein?

The big question is: if I plant a blend of species for chickens to forage, will they eat the amount of protein they need, i.e. 18%for broilers? Also, are they capable of foraging enough food to eliminate bagged feed?
Any thoughts are greatly appreciated  ,Huxley

I don't think broilers will forage enough to fulfill all their caloric requirements.  They grow too fast for that.  I'd look at forage as a supplement to purchased feed.  Give them a 19-20% protein feed and whatever they forage adds to the flavor and nutrients in the meat.

If you're growing heritage chickens for meat that might work better as they grow slow enough that a high quality forage crop may provide what they need.

I am pretty sure that's right; they may forage enough early on, but they grow so absurdly fast that I don't expect they would be able to keep up with their own needs as they get more ungainly.

Heritage alternatives would be much better... just keep in mind that the overall feed consumption from the longer grow-put time means you'll need even more forage on hand... and they are certainly not as palatable to your average grocery-store shopper.