I had a few die last spring, symptoms: Physical 1. They will put their head down , like their scrunching it between their shoulders.like they have no neck 2. They will not eat. 3.They will not drink. 4.You can pick them up about waist high and drop them and they will not try to flap tghier wings. 5. It seems to effect only the females. 6. They will eventually look like penguins. Stool looks normal from what I can tell. I ordered 25 with the Merak vac. and one of them just died at 9 weeks old, They get 17% layer mash. I have been adding Distillery grain to get the protein up to 21% for my Meat chickens Cross Rocks. But none of them have died. The ones that get this will stop laying before they die. I have used teramyician and qurintined them but they still die, any Help out their.