Patridge bantam chicken poorly foot?

[jools+6]

have noticed today that my two big hens , tikka and bhuna are losing feathers on their usually plump thighs . also the fluffy knickers on both girls look starey . the only way i can think to describe it is that their bottoms look like a hamster just before it meets the great hamster god in the sky !! both are stuffing their faces at the moment on apples and wrecking what used to be the garden and eggs are being produced . we have never had a problem with the girls bickering ( apart from dipper and the rabbit who have a mutual dislike of each other ) touch wood , they have always been a tight knit bunch , cuddling up and ganging up on the dog together . any ideas anyone ??