I hatched out that rooster myself, plus he was 9 months old, she had him for 6 weeks which makes him 10 1/2 months old, He did not show any signs except the twisting of the neck, I have talked with a vet and he thought perhaps it could be West Niles, West Niles causes the twisting of the neck. He showed NO other symptoms, no leg paralysis, no diarear, no other symptoms,he ate very well. When he was sick I immediately brought him back to my house to try and cure him of the wry neck. I believe I may have been too late, because the next day he had past. With Marek's FIRST sign is the split, one leg in front, one in the back and they usually develop an immuned to it after 5 Months.. AGAIN, he was 9 months, he was in perfect health when he left my place. NO OTHER CHICKENS of mine is showing ANY signs of sickness or anything. I have over 75 chickens. From youngsters to Adults...The vet ALSO indicated it's a possibitly he could have gotten an EAR infection...