I ordered 16 poults from the hatchery. The first 4 weeks they were doing great. Then suddenly I started loosing them, one by one. They look fine one day, eating, drinking and on the very next day very lethargic, standing or laying in one spot, feathers down and head deep in the shoulders and have closed eyes. Some of them had rattling in their throats and then grasping for the air. They don’t want to drink or eat and them finally they die. The rest are 6 weeks now. This morning 2 of them in condition I described above. Does any body knows what causes this kind of death?