Want know how old my 4 plymyth rock chickies need to be ,so i can put them in coop with my adult chickens . Should i keep them seperated by some fence in the coop? so they wont get beat up by the big girls. My chickies are about 5 weeks old now doing good in our basement brooder coop .and when do i stop medicated feed and start on layer? THX any help is appreciated