I have two silkies, when they were very young, the whole brooder caught coryza, and all of them dead except that two. Now they have grown up, almost 8 months old, one hen and one rooster. They do not show any sign of disease now, but the female never lay eggs. I think other conditions should be right because most of my other hens are laying. One of my friends told me that once a chicken got coryza, even if recovered, they never lay again, he had that problem with several of his chickens. Is that true?