As I wrote a year ago in a blog post, "Grass-Fed vs Grain-Fed Beef and the Holy Grail: A Literature Review," several people have commented that switching from grain to grass feeding could be one of the solutions to the problem with foodborne pathogens in cattle and other livestock. Quotes like these are becoming more common on the Internet and in recent media reports:
“Products from grass-fed animals are safer than food from conventionally-raised animals.” Eatwild, 2008.
“Research has shown that the strains of E. coli most devastating to humans are the product of feedlots, not cows. This is due to the animals being forced to eat an unnatural diet, and not their natural choice, grass.” Grass-Fed Beef: Safer and Healthier, Animal Welfare Approved, June 15, 2008.
I did an extensive literature review and simply did not find support for the belief that switching from grain to grass for cattle feed would make the world a bad place to be pathogenic E. coli. Now comes an article by S. Reinstein, J.T. Fox, X. Shi, M.J. Alam, D.G. Renter and T.G. Nagaraja. 2009, “Prevalence of Escherichia coli O157:H7 in organically and naturally raised beef cattle. Applied & Environmental Microbiology 75(16):5421-5423,” which states:
"The prevalences of E. coli O157:H7 that we observed in organically and naturally raised beef cattle were similar to the previously reported prevalence in conventionally raised cattle," the researchers said. "No major differences in antibiotic susceptibility patterns among the isolates were observed."
Now, before the internet erupts into a belief culture war between grain feeders and grass feeders, I am not saying that the cows themselves may not well be better off eating grass and roaming the range, and I am not saying that feedlots miles wide are not environmental hazards, but I think we need to face the fact that grain vs grass does not mean “E. coli.”