Hello, My chicks are currently four weeks old. They're on a starter/grower formula and get occassional treats. So far they tried meal worms (love) strawberries (love) arugula (favorite) and some other kitchen scraps in small amounts. They have a dish of chick grit in with them. I was wondering at what age to start introducing "tougher" treats, like black oil sunflower seeds or whole scratch grains? Thanks for any advice.