I have about 30 chicks in a grow out coop right now. Most are blue and blue splash marans and some marans/ white rock mix. I would like to sell the pullets which will leave me with quite a few roosters. Right now they are 6-10 weeks old. I am still feeding them chick starter feed. What feed should I switch the roosters to after I sell the pullets? What is the ideal age for processing the roosters.