I've read that curled toes (it was on a rooster I believe) is caused by too much calcium.
IDK if that's true for Cochins or females. It might be something different, but you might check it out; it might be correctable.
I think If they have curled toes as a chick, it's from to much humidity in the bator. It's fixable as a chick with chickie sandals. I think that's how they get it
