Feed question, need some help please

It would be a very good idea to add free choice grit and oyster shell to their diet - generally all should have access to some type of grit, and laying hens should have access to oyster shell. Since the 18 week olds are close to laying, they can eat the oyster shell as they choose and the little ones can ignore it until they need it.

Although the older hens should be switched to Layena when they start laying, maybe you could transition over to it slowly so the younger ones are still getting the grower/finisher feed. Say, after the hens start laying start mixing some Layena in each week, and gradually add more - until the younger ones are also laying and they'll all be on 100% Layena? Just an idea.

 

Give them free choice oyster shell and grit. Use the Start and Grow you have left. Instead of switching over to Layena, go to Flock Raiser. That will be good for them all. The RIR's will eat the oyster as needed. When the BO's get old enough go to Layena.