The effects of early exposure of cellulitis-associated Escherichia coli in 1-day-old broiler chickens.

Two experiments were performed to test the effect of various field strains of Escherichia coli of cellulitis origin. In the first experiment, 1-day-old broiler chicks were challenged with one of two E. coli field strains using inoculation routes including oral gavage, swabbing of the navel and subcutaneous injection. No cellulitis lesions were produced, although the birds experienced high levels of septicemia/toxemia, characteristic of colibacillosis. The birds that received the E. coli by subcutaneous injection experienced the highest rate of mortality, while those that were challenged by gavage and those that had their navels swabbed experienced lesser rates of mortality. Birds in the second experiment were challenged at 1 day of age with one of three field strains of cellulitis-origin E. coli administered alone or in combination (1:1), which were serially diluted prior to subcutaneous injection. No significant differences in body weight, mortality or cellulitis rates were associated with specific isolates given; however, significant differences were seen with mortality and cellulitis rates according to the dilution of bacteria given. A linear effect was also noted with body weight at 3 weeks, again correlating to the dilution of bacteria that the chicks received.