I made a garland with my fresh herbs to hang in my chicks brooder, they are 11 days old, they loved the fresh rosemary and sage, I also gave them raw oatmeal with grit mixed in, they all dived in to eat it.
Today was their very first day outside, they followed me around in the yard and came...
It's tablespoon, I use 2 tablespoons per gallon of water and it works great, you can also try giving them a mashed up hard boiled egg.
Have you checked the temp in their brooder, sometimes stress causes the pasty butt, it can be that they are cold.