I noticed one out of 150 CornishX this morning with almost no feathers. The birds are over 4 weeks old, have been in a Salatin-style tractor for over two weeks. All the others look normal. This one chick has maybe 1-inch long wing feathers, but is essentially bald elsewhere. The feathering looks like what you might see in a week-old chick. He seems healthy, about the same size as the others. Any ideas?