I have 12 five-month old chickens, 11 hens-1 roo. On the hens, I can feel their breast-bones. Is that normal? They have food and water available to them at all times, get a daily treat, and free-range from morning till dusk. I haven't seen any worms in their poo, sometimes it's a little runny, but more often it's normal looking poo. I attributed it to something they were eating. A couple of my hens seem pretty skinny to me. Could this be a worm problem, or is the breast-bone supposed to be so prominant?