Nicholas Kristof recently published a disturbing column—disturbing even by Nicholas Kristof standards—on an undercover video from the Humane Society of a Kentucky pig outfit named Iron Maiden Farm (really). The operation—a typical embodiment of Big Agriculture—was caught feeding a slush of piglet intestines to sows to establish immunity against a devastating disease called porcine epidemic diarrhea (PEDv). This technique, "controlled exposure," is "widely accepted," according to the Kentucky Livestock Coalition.
The virus broke out last May in Iowa and has killed over three million pigs nationwide. As a way to avoid this intestine smoothie, Kristof urged consumers to forgo factory-farmed pork in exchange for pork produced by small farms. He sites the well-known Niman Ranch as an example.
Consumers would be foolish to trust the old axiom that "humane" small farms are inherently safer than their larger counterparts.
This advice seems perfectly sensible—and in many cases involving porcine disease it would be. Swine consolidation can enhance the spread of certain pathogens. However, in the instance of PEDv, the connection between farm size and disease is tenuous at best. Small farms, according to many experts I've spoken with, turn out to be every bit at risk of getting hit with an outbreak of PEDv as large ones. “This virus doesn’t discriminate,” says Dr. Russ Daley, a South Dakota State University Extension Veterinarian with whom I spoke the day after the HSUS expose dropped. In fact, Daley had recently spoken with a family farmer with 40-50 pigs who experienced a deadly outbreak of PEDv.
This is precisely the kind of detail that media coverage of factory farming almost never includes. Too often, it reduces the broad continuum of animal agriculture to "factory farming" and "humane farming." But agriculture is much more diverse than that. Farms don’t break down into simple categories.
Dirigo Quality Meats, a company that provides pork farms of all sizes with biosecurity plans, draws on sound veterinary science to highlight an important culprit behind the spread of PEDv. It’s not farm size. Rather, it’s birds. DQM writes:
So what farms are at risk? Right now, this virus has been identified at large hog operations, but, that’s where the vets and research money are. Smaller producers who can’t or don’t implement practices are at very high risk. ... If there are birds coming in and out of the tractor trailers parked outside, those birds are flying to other farms.
DQM advises pig farmers to “keep birds away from pigs and practice biosecurity,” but tellingly notes, “that’s all well and good for large hog farms with indoor housing and multiple trucks for transportation, but what’s a small diversified farm to do?” (Of course, the answer is hire DQM!)
There are other factors to include when evaluating Kristof’s advice to avoid PEDv-infected farms by sourcing pork from small farms. Many experts suggest that small farms are less likely to report an outbreak of PEDv in the first place.
“Undoubtedly, more farms have PEDv than is reported in the official count,” Dr. Ron Plain, an agricultural economist at the University of Missouri, told the PORKNetwork. “I think it is reasonable to estimate that the official count of infected farms is less than half of the actual total. I suspect small farms are less likely to pay for the confirmation test than large ones.”
Other considerations challenge the connection between farm size and PEDv prevalence. Transportation to and from the farm—particularly by the trucks that bring pigs to slaughter—helps spread the disease. Pigs from small and large farms typically go to the same slaughter facilities, according to Daley. Furthermore, PEDv has been linked to commercial feed, which both confined and pastured pigs consume in abundance. In fact, according to Daley, small farmers may be more reliant on externally sourced commercial feed than big farmers, which often produce their own feed on site.
Daley correctly notes that “we have no direct comparisons” on small and large farms. But in one study of PEDv prevalence on North Carolina pig farms, operations that tested positive for PEDv had an average herd size of 4,683. Those that tested negative had a herd size that was almost the same, at 4,035. What mattered when it came to the presence of PEDv wasn't the size of the farm—they were all pretty big—but the visitation of trucks. Positive sites had double the truck traffic than negative sites. "Site capacity was not significantly associated with PEDv," the study concluded.
There's a common assumption among very prominent writers who cover food and farming that size matters when it comes to the spread of disease on animal farms. I wish matters were so simple. While this correlation may sometimes be the case with some diseases in some places, there’s very little to suggest that it’s true for PEDv (and other diseases—see this, this, and this). Consumers would be foolish to trust the old axiom that "humane" small farms are inherently safer than their larger counterparts. Animals raised in low density on pasture might be happier, but not necessarily healthier.