Are Parasites Plaguing Pastured Pigs?

Pigs Sugar Mountain Farm Pasture

©2007 Walter Jeffries, Sugar Mountain Farm

Here’s the story: Hogs were moved from being raised outdoors to being housed in temperature-controlled modern hog barns with about a thousand other hogs confined in pens for the welfare of the animal and safety of the product. No more harsh weather. No more parasites. So we’re told. Are parasites such a problem that we can’t safely raise hogs outdoors? Let’s find out.

One of the main concerns in pork is Trichinella spiralis which can cause disease in humans. I should note that currently only 0.013% of the U.S. swine herd is thought to be infected according to the CDC.

From the Pork Checkoff (

The factors that have made U.S. pork safe with respect to Trichinella infection are all related to changes in production practices which eliminate these risks, including banning of uncooked waste feeding in all states and movement to confinement housing systems. Pork production in bio-secure housing systems with hygienic requirements for feed and feed storage and adequate rodent control drastically reduces the risk for exposure of pigs to Trichinella.”

From a 2001 report by the CDC: “The decrease in cases has mirrored the decline in prevalence of Trichinella in commercial pork products. In 1900, the trichinellosis prevalence in U.S. swine was estimated to be 1.41%. The estimated prevalence decreased to 0.125% during 1966–1970 and to 0.013% in 1995…Historically, the major sources of Trichinella-infected pork were swine fed garbage containing animal waste products…Other risk factors for Trichinella-infected pork include consumption by swine of small mammals infected with Trichinella, including rodents, raccoons, skunks, and opossums, and cannibalism among swine within an infected herd.”

So the mainstream story is that raising pigs outdoors means a greater likelihood of parasite infection and we need to continue the intensive barn confinement system to control the risk. But couldn’t this same decrease in likelihood of infection be achieved by knowledgeable pasture-based pig farmers? If we’re not feeding animal waste products to pastured pigs, then isn’t the only concern rodent & small mammal control? Do we really need confinement barns just to keep a few mice out? How many skunks are pigs eating out on the pasture? What if one single rodent gets into the confinement hog barn? It’s certainly possible. Mice manage to squeeze into households all the time. Let me propose that the primary reason for bringing hogs off the pasture and into the confinement barns has little to do with the safety of the pork products. Rather, confinement is only a tool to maximize production and minimize cost while reducing animal welfare and increasing environmental risk.

If you read this report by Intervet, Inc. (manufacturer of worming medication, apparently a division of Merck Pharmaceuticals) you’ll find out that parasites are a BIG problem in confinement operations. So much so that the reason for the report is to urge you to purchase their worming medications.

I’d like to share some quotes from a pastured pig farmer named Walter Jeffries who operates Sugar Mountain Farm in Vermont with his wife Holly and the rest of the Jeffries family.

From Walter Jeffries:

Reality Check #1: Factory farms routinely use heavy doses of medications to kill off parasites. Simply ask them what wormers and other medications they use injected or in their feeds. It will scare you.

Reality Check #2: We pasture and do not need to routinely use medications, antibiotics or chemical wormers to kill of parasites or such in our pigs or other livestock. Instead we use managed rotational grazing and natural feeds to produce healthy animals. We have never had any problems with parasites in our meat. Our meat is a higher quality and healthier product because it is raised naturally and humanely on pasture. Consumers who care about the animals, quality and their own health buy from pastured farmers and avoid the factory farms.”

Conclusion: Is keeping pigs in indoor confinement one way to reduce exposure to Trichinella? It would appear so and the industry would certainly push this point. They’re obviously depending on the use of worming medications though. But is it the only way? Certainly not. Pastured pork can be very tasty and parasite-free. There is no need for intensive confinement pork. Pasture-based farmers like Walter & Holly Jeffries are proving that they can get the same results as the “biosecure” conventional hog barns but with a much more sustainable, humane and environmentally friendly operation. Why are conventional farmers giving worm medications to the “safer” confined hogs? Sure, there are other worms than Trichinella. But why do farmers need to give worm medications to a “biosecure” pig that is “safer” because of “confinement.” That’s a good question. I think it’s one the conventional industry does not want to answer. And remember, just cook your pork to at least 145° to kill trichinella!

Bonus Link: Here’s an interesting NY Times Op Ed piece from 2009 about Trichinella and pork.

Bonus Observation: There’s a lot of talk about “biosecurity” by factory farmers when referring to keeping hogs safe from disease. Yet, every time I watch a tour of a modern hog barn on YouTube (for example) I always see a farmer in plain clothes walk up to the feeder and sift their bare hands pretty deep into the actual feed. How is that “biosecure?”


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