Here is a link for nutrient requirements for layers, broilers and turkeys.
When starting new chicks, go by the list of nutrients for broiler type chicks. Find out what is in the things you are feeding and then find other feedstuffs to provide what is missing.
For example, if your food is missing zinc, selenium or vitamin A, find foods that are good sources of those things.
A vitamin and mineral supplement will always be necessary without a complete chicken feed.
https://extension2.missouri.edu/g8352
If any of the 40 nutrients chickens need are missing or deficient in the diet, there will be developmental problems, nutritional disease and likely premature death..
Remember chickens are omnivores, not seed eaters or even vegetarians. If fed exclusive grains, they won't make it. Feeding some animal protein will likely satisfy their needs for essential amino acids but then there is still the vitamins and minerals.
Whataaa awesome table for nutrients I print it thanks buddy