About this time last year, I published a controversial article in the New York Times suggesting that free-range pigs had a higher risk of contracting trichinosis than confined pigs. My primary source was a peer-reviewed article that had received funding from the National Pork Board. Because the study had been published in a widely respected academic journal, I chose not to mention the funding source. My intuitive sense was that highlighting the industry connection would immediately prevent skeptics from reading further.
Big mistake. The food world pounced, the Times printed a shaming "editor's note," and I spent much of 2009 contemplating moving to West Texas and living in an underground house.
Lost in all the huffing and puffing over my omission, however, was the gist of the underlying question itself: to what extent are animals raised under free-range conditions prone to contracting diseases that can affect humans? Please understand that the point of exploring this question is not to promote the highly charged thesis that factory-farmed animals are better. Instead, the only goal here is to raise awareness about a method of farming animals that has—primarily on account of its status as a preferred alternative to concentrated animal feed operations (CAFOs)—escaped the critical scrutiny we've so dutifully applied to factory farms. The claim that free-range meat is a healthier option is a commonly heard bit of culinary wisdom. For anyone who eats meat, some hard scrutiny should be welcomed.
Since writing my disastrous Times piece, I've come across considerable research—none of it undertaken with corporate funding—that provides a wealth of information to help us assess the relationship between free-range animal farming and disease. In a study exploring rates of Trichinella and Toxoplasma in pigs raised in the Netherlands, several Dutch microbiologists found that their evidence "indicates that the prevalence of parasitic infections is higher in outdoor farming systems than in indoor farming systems." An investigation of a Trichinella outbreak in Sardinia (which was long considered free of the disease) observed that the "parasite is restricted to free range pigs." In Switzerland, a study of free-range pigs and Trichinelli defined "free ranging pigs" as "the group with the highest risk of exposure." (The study found very low rates in all systems studied.)
Infections seem to intensify in regions of the world that lack adequate sanitation. In a study of free-range pigs in Mozambique, the authors concluded that "free range pig management system represented by far the most important risk factor for porcine cysticercosis"—a disease caused by a tapeworm larva. In Nigeria, pigs "reared by intensive system" had lower rates of bacterial infection than "the population of local pigs on free range." (Click here for a PDF of the study.)
Poultry has come in for its share of critical analysis as well, at least in the trenches of academic science. A study of Salmonella and free-range (and certified organic) chickens found that 31 percent of the 135 chickens sampled tested positive for the deadly bacteria. The authors were moved to warn that "Consumers should not assume that free-range or organic conditions will have anything to do with the Salmonella status of the chicken" (PDF). An investigation of Taxoplasma gondii (a parasite potentially fatal to fetuses) and free-range chickens in China reported that free-range birds showed an infection rate of 34.7 percent. Caged chickens had an infection rate of 2.8 percent. A similar study undertaken by the USDA's Agricultural Research Service reported that "A very high prevalence of the parasite (Taxoplasma gondii) was found in chickens raised in backyards (up to 100 %) and free range organic (30-50%) establishments." It further noted that "overall, prevalence of viable T. gondii in chickens raised indoors was low" (PDF). Swedish veterinary scientists had their findings summarized by a medical news outlet with this headline: "Free Range Chickens are More Prone to Disease."
Although these studies gained virtually zero media attention, not everyone has ignored their implications. The Humane Society of the United States—an organization fiercely dedicated to issues of animal welfare—put out a report in 2009 acknowledging the many virtues of a well-managed free-range operation. At the same, though, the report frankly admitted that "outdoor flocks may be exposed to wild birds, insects, and other potential infectious agents, and may come into contact with bacteria and intestinal parasites." It wrote that "Pollorum disease, a type of Salmonella infection, is currently rare in commercially raised chickens, but may occur in backyard flocks." And it even mentioned that "caged hens are generally protected (from the intestinal parasite Coccidia) by separation from their fecal material."
It's time concerned consumers take a page from the Humane Society and look squarely at the research. The idea of a free-range animal is appealing in so many ways. The animals are almost certainly happier. They are also removed from the battery rounds of antibiotics and vaccines that keep them growing in caged systems. They allow consumers to feel better about eating meat. But, as these very recent studies all suggest in one way or another, free-range—however it ultimately stacks up against confined methods—comes with its fair share of problems.