Because of the 2012 drought, high levels of toxins (alfatoxin, mycotoxin) have been found in corn crop. This can cause many problems in your chickens, especially with breeders. Commercially made feeds will sometimes contain toxin binders which will eliminate poisons but please check your labels. If you feed your chickens cracked corn or grind your own corn, please test it for poisons! Please look alfatoxin and mycotoxin up on the internet. I know it's in some dog foods and the symptoms for dogs are:bloating (Which can kill them) loose stool, abdominal cramping, and death.