One of our hens had a rather runny bum and sticky feathers .We googled and founf that feeding them a mixture of Natural Yoghurt and scotch porridge oats , mixed together so it makes a thick ish mix had sorted her insides out really well . She now has lovely fluffy feathers round her bum and they all go mad for their weekly treat (or if mrs has her way , every other day) . We just buy supermarket value yoghurt and a big bag of oats for less than £2 .The bag of oats lasts several weeks , so its a cheap treat and very good for them .
Just remembered , also adding some cider vinegar to their water helps as its a natural antibiotic :-)
Hope this helps , Mark