I went to buy grit the other day as my chicks are 3 weeks old. They told me that I shouldn't need it if I am only feeding them feed store food. She also said that if I let them free range they should be picking up their own little rocks so I shouldn't need it. I wanted to give my chicks some treats like a mashed up hard boiled egg. Will they need grit? Will I ever need it and what age should I get it at?