I have a pair of bantam cochins and I'm finding their feet are difficult to keep clean. When I got the birds, they had crud in their foot feathers. I have tried cleaning most of it off but daily they get dirty again. What is the best way to keep their feet clean? I realize they won't constantly stay clean becaus they live on the ground, but I would think having mud and poop get in the feathers wouldn't be very good for them (yes, I do keep the coop clean).