I'm trying to avoid buying two types of feed. One for 6wk old chicks and one for layers. I've been using a non medicated grower that is 18% or 20% protein and supplementing layers with oyster shell. Seems to be working fine; no reduction in egg production. Is this healthy for the birds? Also, my husband just bought 24% starter by accident. Can I feed this to my layers until the next bag or should I return it? Thanks for the help!