Well they have a large pen to forage in, but other than the layer feed and chick starter (I alternate now that they're older, did the same for my runner and never had problems) when they were younger they just had the starter though... I feel like its not the diet although it's possible ive never had problems and ive had many many poultry.. Theyre very wobbly though now, still eating and drinking a little but stumbling every few steps. It seems to have gotten worse with one of them, but ive been away all weekend and havent been keeping a close watch on them . No supplements...
Hard to monitor but i think they also have runny watery poop, unless they were just drinking a lot like ducks do..
Did you recently start a new bag of feed? Are you getting a lot of rain where you are? Run off coming into pen? Are there mushrooms growing in your pen? I would stop feeding from the bags you have now to be safe. Make sure they have plenty of fresh drinking water.
