I have not been able to find a bag of "grit" in our city. Can i use gravel that is sold in the pet store for bird/parrots? Scratch is another thing i keep reading i need. I can only buy it in 50# bags. I only have 4 chickens and storage of the food,bedding plus add the scratch would be a lot. Any idea what i could use that i could get in a smaller amount?? Right now they have an outside area i put sand in, but soon winter will be here and they won't be able to use it.