I heard recently that perhaps current CAFO beef feeding operations that are often blamed for salmonella poisoning, not because cows spread salmonella, but most because cornfed cows spread salmonella. The acidification of their stomachs from all that corn cause them to carry high amounts of pathogens that they would not normally have problems with. One of these pathogens is salmonella. Here is a very interesting interview detailing the life of a cornlot cow from birth until death: http://www.math.uic.edu/~takata/some_articles/FreshAir_Michael_Pollon_on_beef_industry,_hormones,_antibiotics.html
One of the things of note in this article is when they mention that one reason why corn is the feed of choice is because it is subsidized and so is much cheaper, even cheaper to buy than it actually cost to grow. So basically, your tax dollars help pay for the corn these cows eat.
The other thing of note is that the acidification and contamination of cow rumin also breeds acid loving strains of bacteria and disease. And since humans naturally have acidic stomachs as well, diseases bred in acidified cows are much more aggressive and successful in the human digestive tract than diseases bred in the natural neutral PH stomachs of naturally foraging cows.
SO basically, as the article describes, you end up with these sick cows digesting corn and all around them are giant open vats of feces contaminated with salmonella and all kinds of things. (and I can attest to the veracity of how bad these places smell as you can literally begin to smell the horrible stench from 10 or more miles away) But one thing I was told, and I am still looking for info on this, is that because the cornlot cows are fed corn, all the surrounding wild life that likes grain will sneak in at night and try to steal what corn they can get as well. That includes mice, rats, birds, rabbits, deer etc. All these wild animals track through the feces and consume the feces infested grain and because the feces are infected with so many diseases, many of the wild animals can take on these pathogens and also further spread them in THEIR feces. This is how salmonella can easily escape a corn lot and make it 5 miles away to contaminate a lettuce farm. It's not just water runoff that can do it. All the wildlife near a corn lot are infected carriers that infect the entire area. Anyone have any more info on this second bit? It sounds logical but I haven't yet been able to find any info on salmonella and other pathogens passing from cow feces to wildlife.
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Beef is contaminated POST SLAUGHTER, Salmonella is an intestinal tract, then blood borne illness. Once blood borne things are going down hill VERY fast in either human or beast. If you get food poisoning from contaminated meat it most likely was contamed after butchering. That being what it is, grain fed cow meat has a propensity to become infected that is higher than grass fed, for what thats worth.
Most food is contaminated while being handled, ie the salmonela/ecoli is not (inside) the food.
Hi Eva. You've asked another interesting question!
I spent about two hours yesterday searching the peer-reviewed literature for an answer. I found only one study that looks at transmission of salmonella between CAFO livestock and wildlife.
If any other papers have been published on this topic, it's likely that they are listed in the references in this study, but unfortunately I can only see the abstract. Maybe somebody with access to the whole paper can look at the references and post them here.
In this study, which was done on cattle feedlots in Texas, the authors looked at a particular type of bird (European starlings) and measured the degree to which these birds contaminate food and water on the feedlots.
I know this is the opposite of what you asked, but it's the only thing I found so far in the literature.
The authors found that on feed lots with more starlings, the water and feed are more heavily contaminated with salmonella.
Carlson JC, Franklin AB, Hyatt DR, Pettit SE, George ML. The role of starlings in the spread of Salmonella within concentrated animal feeding operations. Journal of Applied Ecology. 2010 Dec (epub in advance of print). DOI: 10.1111/j.1365-2664.2010.01935.x http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2010.01935.x/abstract
This is one of those situations where just referencing wikipedia should be more clear than the specifics:
Salmonella occurs pretty much everywhere, since it is a bacteria. The corn per say is not causing the problem (although the negative impact on cow health would be a factor). But the issue is that mass farms are basically cesspools of bacteria growth.
Many "good" organic and some pastured animals, when grown on a large enough scale, will have similar issues. Cleanly disposing of that much waste just is not doable (indoor plumbing aside and mass water treatment can do it though, so if you can potty train a cow....). Kind of like how massed dairy cows end up with rotting hooves from their feet being constantly soaked in urine.