Roundup

Switch to hay diets won't cure E. coli threat

University of Idaho researchers say a change from grain to hay in cattle diets will not eliminate the threat of lethal E. coli in beef.

The Idaho research refuted an earlier study by a team of Cornell University researchers that suggested switching to a hay diet would significantly reduce the E. coli threat to humans.

"That study claimed that if cattle were fed hay, the E. coli they shed would be sensitive to acid and would be killed in the acidic conditions in the stomach," said UI microbiologist Carolyn Hovde Bohach.

The UI research was reported in the July 1 issue of Applied and Environmental Microbiology by Bohach; laboratory technicians Paula R. Austin and Karen A. Cloud, both UI graduates; UI statistician Christopher J. Williams; and UI animal scientist Carl W. Hunt.

Their test group of eight Holstein steers experimentally dosed with E. coli O157:H7 harbored the bacteria longer while fed a hay diet than while fed a grain diet. The grain diet was similar to the traditional finishing diet fed to cattle before slaughter.

The Idaho study also showed no difference, as a result of the two diets, in the acid resistance of E. coli 0157:H7 passed by the cattle in feces.

E. coli O157:H7 can be lethal to people, particularly children, the elderly, and those with weak immune systems.

Unlike people, cattle carrying the bacteria show no symptoms, and only a small percentage of cattle test positive. Meat packing companies take precautions to prevent contamination of meat during slaughter and have adopted new methods, such as steam-sterilizing carcasses, to kill bacteria. --Bill Loftus