Is a Free-Range Pig a Good Pig?

by Bill Chameides | April 23rd, 2009
posted by Erica Rowell (Editor)

Permalink | 2 comments

A free-range pig is happier than a confined pig. Perhaps. But is a free-range pig safe to eat? A recent op-ed in the New York Times by James E. McWilliams (“Free-Range Trichinosis,” April 9, 2009) argues “no.”  Let’s take a closer look.

McWilliams, a history professor at Texas State University, cautions against the trend toward raising poultry “naturally,” writing that a study published in Foodborne Pathogens and Disease “brings us closer to a more concrete idea of why the free-range option can pose a heightened health threat to consumers.” Rather than “setting the animal world partly free,” McWilliams suggests that “we might have to take greater control of it.” And concludes that “if clean and humane methods of production cannot be developed, there’s only one ethical choice left for the conscientious consumer: a pork-free diet.”

The McWilliams op-ed set off a mini-firestorm in the blogosphere (see here, here, here, and here) with many free-range advocates crying foul (sorry could not resist). And much has been made of the fact that the study McWilliams used for the data cited in his op-ed was funded by the pork industry. Except for the New York Times’ failure to disclose this on the publication date, for me the fact that the pork industry funded the study is moot. I have no reason to believe that the study’s scientists fudged their results, and suggesting they did without specific evidence is irresponsible. Moreover, McWilliams concludes his op-ed with the notion that we might ultimately have to opt for a “pork-free diet.” Not exactly a message the folks from the pork industry want to promote.

But after all the hype dies down and the dust settles, we still need to know what it is we are eating. So what did the paper in Foodborne Pathogens and Disease actually say?

The Science

The paper [pdf], Seroprevalence of Trichinella, Toxoplasma, and Salmonella in Antimicrobial-Free and Conventional Swine Production Systems, was written by Wondwossen Gebreyes of the College of Veterinary Medicine at Ohio State University and colleagues.

As the title indicates, three pathogens were studied:

  • Salmonella  – the baddie bacteria that has been a frequent front-page feature thanks to food contaminated from spinach to pistachio nuts (more info here);
  • Toxoplasma gondi – a parasite most frequently found in cats that can prove fatal to a fetus when the mother comes in contact with it as well as to immunodeficient individuals (more info here); and
  • Trichinellosis – the parasite that causes trichinosis, a disease that can be fatal and for which there is no silver-bullet treatment (more info here).

Clearly these are all bad news. So does eating free-range pork increase your chances of getting one of these?

To answer that question, Gebreyes and colleagues looked at the prevalence of the pathogens in pigs raised under two distinct production systems: “niche-market, outdoor, and antimicrobial-free” (i.e., free-range and without prophylactic use of antibiotics) environments and “intensive indoor (conventional)” ones in North Carolina, Ohio, and Wisconsin.

Specifically, they compared the prevalence of reaction to the antibodies of the three diseases in the blood of 324 free-range pigs with that found in 292 pigs reared using conventional, confined practices. (Because the authors looked for the prevalence of the antibody reactions in blood, it is referred to as “seroprevalence.”)

The study showed that the pathogens were more prevalent in free-range pigs than in conventional pigs. The results for salmonella and toxoplasma look to be significant but certainly not alarming. For salmonella the prevalence varied from 54 percent for the free-range pigs to 39 percent in conventional pigs; for toxoplasma it was seven percent versus one percent, respectively. There was also a difference for trichinella, but it was marginal at best: no trichinella was found in the conventional pigs while it was found in two of the 324 free-range pigs.

The Bottom Line: To Eat or Not to Eat

I find the Gebreyes et al. findings quite believable. Free-range pigs by definition live in a less-controlled environment that should lead to greater exposure to a whole variety of microbes and parasites and thus a higher incidence of pathogens.

Whether or not that means you should or should not eat free-range pigs (or any free-range meat) is a personal decision. But as you make that decision there are two important points to keep in mind:

  1. Contraction of all three pathogens considered in the Gebreyes paper can be easily avoided through proper hygiene, such as frequent hand-washing when handling uncooked meat and proper cooking that brings the temperature of the meat to high enough levels to kill the bacteria or parasite. The Centers for Disease Control and Prevention has specific instructions for how to avoid the diseases: salmonella, trichinosis, and toxoplasma.

    If you choose to eat free-range meats, it would probably be a good idea to be extra vigilant. And if you are, then the free-range option should not pose the heightened health threat that McWilliams posits.

  2. There are risks associated with eating conventional pigs and other meats, for example from the presence of growth promoters and antibiotics.
  3. Eliza McLean, a free-range pig rancher in North Carolina, argues one way is not necessarily better than the other. In an email, she wrote: “It is all about the management. It can be done right in the confinement setting, and wrong in an outdoor one.” The rest of her message explicated the vice versa.

In either case, keep in mind that food choices also have environmental implications, so my recommendation is: enjoy but be mindful.

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  1. Bill Chameides
    Apr 24, 2009

    It depends on what you do with the waste and how many pigs per acre you have. Most concentrated animal feeding operations (CAFOs), which of course confine their livestock, have horrendous water and soil pollution problems.

  2. Chris Hagin
    Apr 24, 2009

    Wouldn’t the widespread use of free-range pig farm management practices also have a serious negative impact upon soil and water resources nearby such farms? More conventional pig farms may be able to regulate their impact on the local environment more stringently than free-range ones.

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