Daft question if you want to feed natural then why bother with layers why not feed naturally once set up it's easy enough, I feed a mix of layers and other 70%-30% for my hybrids and 25% - 75% for my rare breeds
I use wheat, sprouted wheat, mussels, sugarbeet, dandelion tops (I use the root for coffee), spinach and some greens, sprouted wheat being the largest component.