ANATOMOPATHOLOGICAL AND CLINICAL FINDINGS IN WHITE LEGHORN LAYERS CAUSED BY Ornithobacterium rhinotracheale AND Escherichia coli UNDER CONTROLLED CONDITIONS

Abstract

This study aimed to determine the clinical signs and pathological findings caused for Ornithobacterium rhinotracheale and Escherichia coli in White Leghorn layers under controlled conditions. A total of 80 replacement hens of five weeks were selected. Before starting the experiment, microbiological tests were conducted in 16 chicks to verify if they were exposed to pathogens. The remaining 64 chicks were distributed in four equal groups (n=16). On day 1 of the experiment G1 and G2 were inoculated via intranasal with 0.6 x 107 UFC/ml of O. rhinotracheale and G3 and G4 (negative control) received brain heart infusion broth. Forty eight hours later, G2 and G3 were inoculated via intranasal with 0.6 x 107 UFC of E. coli. Four chicks per group were slaughtered on days 3, 7, 14, and 21 after inoculation and samples were collected from paranasal sinuses, trachea, lung, air sacs and liver for optic and transmission electron microscopy. In addition, histochemical techniques (PAS and Weigert) were used to show the presence of mucus and fibrin in respiratory organs. The study allowed evidencing a delay in the growth rate and presence of lymphoid tissue associated to mucosa in chicks inoculated with O. rhinotracheale and E. coli.