My welsummer is on the slim and thin side. She has liquid poop that dries dark. http://chat.allotment-garden.org/index.php?topic=17568.0 Hers is a mix of oily and foa/ceacal. She is really thin she eats just like the others. She is active like the others. She is very bony to pick up. It is very unconfortable for her. It has been like this for a few weeks. She is 20 weeks old now. The other are fine. I add grit when they need it. So I worry for her. I am no chicken expert.