Scientists Examine E. coli Levels in Animal Feed

CLAY CENTER, Neb.Scientists at USDA's Agricultural Research Service (ARS) are studying the relationship between the use of  wet distiller's grains with soluble" (WDGS)a byproduct of ethanol production that is sometimes used as a cattle feed ingredientand the incidence and persistence of Escherichia coli O157:H7 in cattle manure and on animal hides.

WDGS are rich in protein, and also provide calories and minerals, according to James E. Wells, an ARS microbiologist who has been studying the pros and cons of WDGS since 2007. He said cattle are a natural reservoir for E. coli, which is apparently harmless to them, but can cause illness in humans. E. coli in manure can newly infect or re-infect animals in pastures and feedlots; if E. coli ends up on the animals' hides, it could subsequently contaminate meat and equipment at the packinghouse.

In early experiments with 608 steers, the researchers showed the incidence and prevalence of E. coli O157:H7 in manure, and the incidence on hides, was significantly higher for cattle whose corn-based feed included 40-percent WDGS than those whose feed did not include WDGS. They plan a follow-up study to determine what causes the difference in E. coli levels, and what can be done to reduce them.