Decal Shedding and Rumen Growth of Escherichia coli O157:H7

摘要

Nine weaned calves aged from 8 to 12 weeks were fitted with rumen cannulas and were inoculated by cannual with 10~10 CFU of a five-strain mixture of nalidixic acid-resistant Escherichia coli O157:H7. Six calves were fasted for 48 h on days 15 And 16 and days 22 and 23 after inoculation. Samples of rumen contents and feces were obtained daily to enumerate E. Coli O157:H7 populations and to determine rumen volatile fatty acid (VFA) concentrations and rumen pH. Fasting resulted in a Marked decrease in rumen VFA concentrations from a mean of 135 mmol/liter before the fast to a mean of 35 mmol/liter During the second day of the fast.