I have 14 chickens, someone is laying the occasional soft shell egg, then another lays on it, gets covered in yuk, they then get all depressed in their cleaning! So we washed a chicken (just the underneath!h the other day, and she seems so much happier. But in doing this we noticed a few in our flock have no feathers underneath?! Is this normal?! Why (apart from brodiness) would they do this?! Thank you!