You would do better to buy the unmedicated chick starter or Flock Raiser and mix that with the grain (higher in protein).
Make sure you offer greens (like alfalfa hay cut to 2-3 inch lengths, grass, etc.) since you will be diluting the vitamins also. Also they will likely need the oyster shell mixed in, I have found by experience. Flemingoutdoors.com has a recommendation of how much on their oyster shell page.
Layer has 16% protein
Chick starter and Flock Raiser have 20% usually
Corn has 7-9%
Wheat 12-14%
Millet 11%
Oats I think were 10-13??? I forgot- also depends on hulls or not
Black Oil Sun seeds 16%
Barley I forgot- maybe 10% or so
split peas 24.5%
What I am getting at is that you can mix these up and if you use a high protein base you are better off since I wouldn't go less than 15% for layers. Brand new chicks need the starter by itself until 8 weeks, then you can go down to 17% until point of lay.
I also like to offer Redmond Mineral conditioner for a little salt and minerals (they will feather pick if they don't have enough salt). So when you dilute the commercial feed blend make sure you attend to the oyster shell and salt/mineral requirements. Don't go over about 0.5% salt.