I have several chickens of different breeds, however my Rhodies, one inparticular, is plucking feathers from the rest of the flock. Is there an easy fix to this problem or do I just need to remove the problem poultry? I have heard it is a riboflavin(B2) deficency that affects Rhodies primarily, and my ladies are on a complete feed layer pellet,scratch feed and grit. They get plenty of free rangeing. any thoughts?