Symposium : FARM health and safety Invited Review: Effects of Diet Shifts on Escherichia coli in Cattle

摘要

Escherichia coli O157:H7 is a pathogenic bacterium that causes acute illness in humans, but mature cattle are not affected. E. coli O157:H7 can enter the human fOod supply from cattle via fecal contamination of beef carcasses at slaughter. Previous attempts to correlate the incidence of E. coli O157:H7 with specific diets or feeding management practices gave few statistically significant or consistent findings. However, recent work indicates that cattle diets may be changed to decrease fermentation acid accumulation in the colon. When fer- mentation acids accumulate in the colon and pH de- creases, the numbers of acid-resistant E. coli increase; acid-resistant E. coli are more likely to survive the gas- tric stomach of humans. When cattle were fed hay for a brief period (<7 d), acid-resistant E. coli numbers declined dramatically. Other workers have shown that brief periods of hay feeding can also decrease the num- ber of cattle shedding E. coli O157:H7, and a similar trend was observed if cattle were taken off feed and exposed to simulated transport. These observations in- dicate that cattle feeding management practices may be manipulated to decrease the risk of foodborne illness from E. coli, but further work will be needed to confirm these effects.