When I cook my grass fed burgers, I cook to just barely medium, as opposed to grain fed where I want well done. The reason is, grain fed cows ALL have ecoli in their gut. Grass fed cows (make sure your cow is grass finished as well) don't have anywhere near the same issues.
Aside from the above poster's experience in the lab - this sounds like it can't be true. I mean don't most humans have e-coli in their intestines?
I can't believe that grass-fed cows somehow don't but corn-fed do, that sounds like marketing hype at best and confusion more likely maybe. Also, the issue with e-coli as pathenogenic in meat for consumption is in burgers, not steaks, no, as the heat on the outside of steaks kills it even if the meat is all contaminated on the slaughterhouse floor with intestinal contents, but burgers are ground and the pathogen gets into the interior of the burger which, if not cooked through...