Crumbles chick feed when small. Once chickens get older mine get layer feed. (usually) Sometimes they get all flock feed.
I intergrate chicks with the bigger birds at around 4 weeks. So the young birds eat what the bigger chickens are eating.
If you have a feed mill by there you can see if they have chicken feed. I use agrimaster made by Cargill sold at farm fleet stores.
I grow some corn at neighbors hand pick, shell and grind. I mix the corn with cracked roasted soy beans. I take soy corn mixture and mix with chicken feed. Just saves a few bucks is all and my chickens free range.
Trying to buy grains and have them mixed is going to be more expensive than buying from mill. The feedmill will have a nutritionist which will formulate the feed, or should have one anyway. Many of the premade feeds are corn and soy based. There are feeds which do not contain soy.
If you are not going to freerange your chickens, once vegetation starts growing give them some greens, grass...etc. If you have extra vegetables chickens like vegetables
and fruit.
