E. coli and grass fed cows

Got an email from Michael Ruhlman this AM asking:

are you sure e coli doesn't grow in the guts of grass fed cows? i honestly don't know and would like to. i do know it grows in the guts of dogs, hogs, horses and deer (and the deer part is the scary part because they can spread it in spinach fields). Just curious.

That got me wondering, was I confused? Did I really recall everything I've read correctly? So I poked around in the Megnut archives for more information. Here are two articles that I'd linked to last fall that supported me.

From Michael Pollan's The Vegetable-Industrial Complex October 15, 2006 in the New York Times:

The lethal strain of E. coli known as 0157:H7, responsible for this latest outbreak of food poisoning, was unknown before 1982; it is believed to have evolved in the gut of feedlot cattle. These are animals that stand around in their manure all day long, eating a diet of grain that happens to turn a cow’s rumen into an ideal habitat for E. coli 0157:H7. (The bug can’t survive long in cattle living on grass.)

From Nina Planck's Leafy Green Sewage September 21, 2006 in the New York Times:

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.

Phew! I'm not making things up. Which leads me back to what I said yesterday in Vaccinating against E Coli: why isn't anyone talking about moving cows off of corn feed, even if it's only for the last week of their lives?

5 thoughts on “E. coli and grass fed cows

  1. I think the confusion arose because of the different strains of E. coli. Yes, certain strains of e coli are found in the stomachs of many animals and all over the place, however our stomachs are sufficiently acidic to kill those ‘normal’ strains so they don’t make us sick. Since the diet of grain-fed cattle makes their stomachs much more acidic than normal, O157 is a strain of E. coli that evolved to survive in a more acidic environment. So if we consume this strain, it is not killed by our stomach acid and makes us sick.

  2. E.coli is present in the guts of all mammals. 0157 proliferates in the guts of grain-fed (specifically corn I believe) cattle due to the overly acidic environment. Much like reliance on anti-bacterial soaps actually produces more virulent bacteria, overly acidifying the gut produces more virulent E.coli. As for why they won’t switch them to forage for the last week of their lives, it’s probably because it costs more and consumers aren’t sufficiently p*ssed off enough to do anything about it. Only when consumers hit them in their pocketbooks will they do anything.
    Modern Forager

  3. Dear megen Nut, What a wonderful person you are. Just so you have some understanding about e coli and why its in our food chain. Down here along the border where alot of spinach and other wonderful crops are grown. Pickers will defecate in the fields. Thats an open secret around here. So, dont be suprised when you here about how did it happen, now you know.

  4. The connection between E. Coli O157:H7 and grain-fed cows was shown in a Cornell study that appeared in Microbes and Infection, Jan. 2000, Volume 2 Issue 1 p. 45. I don’t think this study has been seriously challenged.

  5. Pollan also mentions reduction of E. coli O147:H7 by grass feeding in The Omnivore’s Dilemma (p. 82). I checked the notes for his source of the information and it is a self-published book by the author of the study cited by Food Lawyer above:
    Russell, James B. Rumen Microbiology and Its Role in Ruminant Nutrition (Ithaca, NY, self-published, 2002)
    To find the abstract of the Microbes and Infection article (and read the whole thing if your institution subscribes), first visit http://dx.doi.org, then enter doi:10.1016/S1286-4579(00)00286-0 in the box.

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