I'm a first time chicken owner and purchased 4 Orpington pullets a month ago. I frequently see chocolate pudding poop when cleaning the coop and the run. I checked all their bottoms and one has a little bit of white pasty stuff around the vent. They are not yet laying. All four act well and lively with shiny eyes and feathers. They are on pullet crumbles and scratch around the grass in their tractor. What should I do?