Quantitative assessment and comparison of susceptibility to colibacillosis in pure lines of broiler breeders and their commercial offspring.

Colibacillosis, caused by avian pathogenic Escherichia coli (APEC), is a disease of major economic importance to the broiler industry. This study aimed to investigate genetic variation in susceptibility to colibacillosis by comparing four pure broiler breeder lines and their commercial four-way cross offspring. Three consecutive experiments were performed assessing mortality, growth retardation and mean lesion scores (MLS) after E.

Co-infections of and various avian pathogens resulted in varying rates of SPF broilers with an infection.

Typical lesions can be reproduced in SPF broilers after intravenous, aerosol and oral inoculations.The respiratory route is potentially an infection route for pathogenic bacteria.Co-infections tested in this study or dexamethasone do not exacerbate the proportion of lesions.

lesion strains are less sensitive to the hostile environment of albumen and more resistant to lysozyme compared to cloaca strains.

Egg albumen inhibits cloaca strains more than lesion strains. lesion strains are resistant to high concentrations of lysozyme.Lysozyme resistance could enhance survival in albumen and body fluids.