Chick starter/grower: Different protein levels based on type of breed?

Hi All,

I will be raising two breeds of chicks this spring, Langshans and Svart Honas.
I have been reading about optimum protein levels for chicks, and mostly it goes towards a higher level of protein, with a lot of mentions of supplementing with, or completely feeding a high protein game bird feed.
I got to thinking about what I had read when I got my dog, a toy breed, and how most feed recommendations said to feed large breed puppies a lower protein level so as to not outgrow their developing bone structure, and a higher one for the small breeds.

Would the same hold true for the Langshans and Svart Honas? For the Langshans, would you want to start out high with a starter, go low for a grower, then back to an optimum higher protein level as a adult feed, based on what exhibitors feed? Or go with a lower level throughout the growing period? They are slow maturing, and the UK Croad Langshan site recommends the lower protein grower route, and since I want to emphasize strong healthy leg structure to support their weight, maybe that would be the best way to go about it? If so, what percentage protein would I want?
The Svart Honas are a landrace and so much smaller, it seems that they should go with the high protein game bird direction?
The fun part is that I am planning on running them together when growing out. I could keep them separate from hatch for a while, how long do you think?
Let's see how complicated I can make this......

 

If I only knew what they respond to best! Too newbie to know. Haha.

I found the Livestock Conservancy heritage breed feed recommendations, they said that the newer layer breeds are selected for performance with a lower protein level feed, and so they had all old breeds with higher levels. I will go with that.