[NancyM]

Grain fed cows! Grass fed cows don't produce it:

http://www.nytimes.com/2006/09/21/op...=1&oref=slogin

In 2003, The Journal of Dairy Science noted that up to 80 percent of dairy cattle carry O157. (Fortunately, food safety measures prevent contaminated fecal matter from getting into most of our food most of the time.) Happily, the journal also provided a remedy based on a simple experiment. When cows were switched from a grain diet to hay for only five days, O157 declined 1,000-fold.

This is good news. In a week, we could choke O157 from its favorite home — even if beef cattle were switched to a forage diet just seven days before slaughter, it would greatly reduce cross-contamination by manure of, say, hamburger in meat-packing plants. Such a measure might have prevented the E. coli outbreak that plagued the Jack in the Box fast food chain in 1993.