| Popis: |
In October and November, 1952, an epiornithic of infectious bronchitis swept over southern Minnesota and northern and central Iowa. At the time, nearly all flocks in the area were of laying age, and a large proportion of all flocks in the area exhibited symptoms of the disease. Characteristic symptoms were the occurrence of respiratory trouble, with almost the entire flock simultaneously affected; a rapid drop in egg production beginning 2 or 3 days after onset of respiratory symptoms, from perhaps 60 to 85% to a level of 5 to 20% in about 5 days; a marked reduction in feed consumption for the duration of respiratory symptoms (7–10 days) and a gradual increase after that time; slow return to production, with only a few flocks having returned to former levels after 8–10 weeks. Most flocks never did reach former production levels, and most of those that did were late-hatched … |
