Survey for infections of various pathogene in a flock of non-vaccinated commercial broiler chinckens: I. Productivity, clinical signs and pathological changes

摘要

To investigate respiratory disease following "chicken colibacillosis", data concerning body weight, viability, clinical signs and pathological changes were collected weekly from hatching to shipment in a non-vaccinated broiler chickens flock consisting of 20,000 fowls. Productivity scores also were examined. The weekly mean body weight and viability of chickens in the tested flock were almost the same as those of chickens in the adjacent flocks, each of which comprised 20,000 fowls, and were given Marek's disease vaccine (HVT) on hatching day and Newcastle disease vaccine (B 1 strain) at two and four weeks of age. Clinical signs of the tested flock were mainly respiratory symptoms, and the most severe at four or five weeks of age. Pathological changes in the sampled chicks were primarily exudative inflammation in the trachias, lungs and air sacks at four or five weeks of age. At shipping, there were no differences in productivity scores, but there was a significant dissimilarity in appearance of Marek's disease lesions (p. > 0.005) between the tested flock and the adjacent flocks.