There has been a groundswell of interest in filtering swine barns to block swine diseases, most notably for keeping out porcine reproductive and respiratory syndrome (PRRS), but also for preventing the introduction of swine influenza virus and Mycoplasma pneumonia.

An Iowa State University Extension swine specialist says he’s all for that effort. But filtration should be considered just part of a biosecurity plan, realizing that there are expensive up-front costs with filtrations systems, as well as major ongoing costs.

“You have to maintain (fill) the cracks and change a lot of air filters. It could end up being a big cost,” observes James D. McKean, DVM. And filtration might not work for everybody, especially for a lot of the older hog barns that are still in use in the industry and would be expensive to renovate.

“The industry also needs to look at how PRRS spreads and the fact that aerosol is not the most effective means of PRRS spread. Semen has proven to be a fairly efficient method of transfer. And, one that doesn’t get enough credit is trucks or transport vehicles, which I think is big,” McKean stresses. Cleaning trucks regularly between loads of pigs is important and needs to be emphasized. It’s no small job, what with all of the crevices and cracks in livestock trailers.

Then there are standard biosecurity issues, including people movement and equipment, the kinds of things that require effective plans and also cost money, McKean says.

His big four biosecurity concerns are pigs, semen, trucks and people. “Once you’ve got everything lined up in that regard, the next step may be to close off the barn from aerosol contacts. However, I believe that aerosol is more of a random event as opposed to a regular occurrence,” McKean says.

If air filtration is a random event, then the question becomes, how much should a producer spend for protection and what is the reward?

In McKean’s mind, a couple of PRRS breaks this past winter in filtered barns show the foolishness of spending millions of dollars on filtration without first implementing proper farm biosecurity.

Filtration advocates say those breaks just prove that filtration worked; it was biosecurity that failed. But McKean says those breaks just reinforce the value of getting biosecurity right before tackling filtration.

All that begs the question, if biosecurity procedures are maximized in an operation, how much risk is really left?

“And that is where I think the veterinarian and the producer need to sit down and really spend some time looking at that question critically,” McKean urges. “Now there are certain places like northwest Iowa and parts of southern Minnesota where pig density is such that the risk of that random event (disease outbreak) goes up. But for an awful lot of people, that random event is about as likely to happen as hitting the lottery.”

Build Better Biosecurity
“The problem that people are having, and part of what I am responding to is, when I hear people say, ‘we’ll just filter the barn,’” thinking that will take care of barn biosecurity, when filtration should be the last step in the progression, he explains.

“Make your biosecurity better, make it tighter and impact the things that are likely to infect your pigs, such as biosecurity limits on incoming materials, aggressively managing rodents, monitoring farm traffic, etc.,” McKean suggests.

Don’t just focus on the pig trailer. “I am equally interested in that truck driver — where his boots and coveralls have been and what his cab looks like,” he emphasizes. “If you market your own pigs, do you walk over to the scale house? Do you transfer boots and keep the truck cab as clean as you would expect a commercial hauler to do?”

Once all those biosecurity issues have been addressed, then conduct a critical analysis about whether you want to filter barns, McKean says.

“So rank the order of all of your swine disease risks. When you get down to the end, and you still can’t sleep at night, then filter the barn,” McKean concludes.