Everyone has the own preferences. The thing is, a lot of different things work. It's not that one person is right and everyone else is wrong. That's what makes it hard, there are too many right answers.
Does your feed bag have a chart on it telling you what to switch to and when. Many bags do. Some may say to switch from a Starter to a Grower at 4 weeks. Others may say switch at 8 weeks. Some say don't switch at all until you are ready to switch to Layer.
Some people insist that if you don't always feed then an 18% or 20% protein feed, you don't love your chickies while some of us feed a 16% feed after they are finished with Starter. That could be a Grower, it could be a Layer.
There are two basic differences in feeds as far as nutrition. One is percent protein. You'll find some labeled for chickens as low as 15% protein, some as high as 20%. Some people feed even higher protein levels but those are either labeled for meat birds or game birds, not chickens that will be layers. They feed it anyway. My general recommendation is to feed an 18% to 20% protein feed for the first 4 weeks or until the bag runs out. I don't care if that is 4 weeks or 10 weeks or even longer. I want mine to have a fairly high protein level to start them off well. That's mainly to help them feather out faster so they are not in danger from cold.
Then you are on your own. I feed a 16% but if you wand to feed a 20% I really don't care. Either way will not hurt your chickens. If you were raising them for show or for meat I would feel differently.
The other important component in feed is calcium. Layer has around 4% calcium and is typically anywhere from 16% protein to 20%. Laying hens need the extra calcium to form egg shells. All other feeds should have a calcium content of around 1%. They all need some calcium for body functions and bone growth, but studies have shown that excess calcium is not good for growing chicks. Too much can cause internal organ damage or skeleton damage. So don't start Layer or anything with around 4% calcium until they start to lay.
The percent protein and calcium is on the label.
It can be confusing because you have so many options that work. if you want someone to tell you what to do then get a bag of 16% Grower and feed it to them forever more. Never switch to Layer. At around 16 weeks offer oyster shell on the side. Those that need the calcium for egg shells should eat enough oyster shell for that, the others should not eat enough to harm themselves. That's pretty much what I do. But if you want to pick what someone else does and follow that, go for it. I will not be offended at all. Just stay away from excess calcium until they start to lay. They are already past the critical point, they are off to a good start.
