Hmm I haven't heard that. I was using pine but it didn't keep the smell down which is why I switched to cedar. I guess I will give the walnut shells a whirl and see how it goes.
My chickens keep laying on the floor of the coop and not in their brooder which we have built for them. Might be because we use cedar bedding in both area's and its confusing for them.
So my question is can you use kitty litter in the coop? I know you can't use any toxic kinds and no powdery...