i have 4 hens that are 21 weeks old. 3 of them combs have turned red.was wondering if i should start feeding them laying pellets or are they still to young. should add that i also have three hens that are laying but because i mixed them together i have been feeding all of them grower/finisher for the last month. this has not affected the older hens laying at all.but i would like to buy laying pellets for all.are the young hens old enough for laying pellets