hello everyone! i just acquired my very first hens and want to be sure i am feeding them the right crumble, etc,... they were hatched in march and april, making them both 3 and 4 month old hens, roughly. they are very fully feathered if that helps describe their maturity. i have both chick crumble and adult crumble, and wondering should i just mix the two? i keep missing the farmer i got them from on the phone, hoping he would let me know which would be more appropriate. also, when should i introduce oyster (calcium), shells? any info for a newbie like myself would be great!!!! thanks so much, anni b.