STARTER: Chicks (1-8 weeks) need starter feed, which contains about 20% protein, and because they’re growing at lightning speed, they need it. Boom.
GROWER: Because their growth rate has slowed dramatically, adolescents (8-18ish weeks) need grower feed, which doesn’t contain as much protein as starter (about 18%). Congrats, ya’ll, you’re on your way to adulthood!
LAYER: At 18-ish weeks, you have an adult chicken and their need for protein (layer contains about 15%) decreases again. Congrats again, chickens. You’re now adults. Minus a mortgage.
Keep in mind, though, that chickens develop at different paces (kind of like humans do) so watch for signs that they’re ready to move on to the next stage of feed. And when you feel they’re ready, go for it.