Don’t let the best be the enemy of better. When it comes to trailer cleaning and disinfection, something is better than nothing, says Paul Ayers, animal care programs manager at The Maschhoffs. And the research proves it.
Transportation continues to be a source for viral spread of swine disease. A recent study led by Dr. Megan Hood with Reicks Veterinary Research and Consulting set out to assess a modified truck wash protocol, particularly in freezing temperatures in the winter months. Ultimately the study evaluated the risk of not performing a full drying procedure in the field and sampled trailers for the presence of porcine reproductive and respiratory syndrome (PRRS), porcine epidemic diarrhea virus (PEDv), transmissible gastroenteritis (TGE) and deltacoronavirus (Delta-CoV).
“Many of us are familiar with the gold standard – washing and disinfecting a trailer and then drying that trailer up to 160 degrees Fahrenheit and maintaining that temperature for 10 minutes,” Hood said at the Allen D. Leman Swine Conference. “That process has been well studied to show that it works. Producers may not do it because of the high investment of a full drying procedure for trailers.”
Testing a Lower-Cost Alternative
Hood evaluated a modified procedure washing and disinfecting trailers, then drying those trailers by heating them enough to remove water off of the surface of the trailer.
“We know if the disinfectant freezes, it’s going to stop the action of that disinfectant,” Hood says. “We didn’t want to wash and disinfect the trailer, and then immediately pull it out of the truck wash and have that disinfectant freeze and stop that action.”
The researchers looked at 50 market trailers transporting market pigs coming into a truck wash. The trailers were scraped to remove the majority of debris, washed with high pressure, blown out to remove water, disinfected with Synergize at a rate of 1:120, and dried for 20 minutes. They tested the trailers on arrival, after washing, after disinfecting, and finally after that 20-minute drying period. They also followed the trailers when they were pulled out to see if there was any frozen water on their surface 30 minutes later.
“We found that 12 of those trailers were positive for PEDv and 6 for Delta-CoV on arrival to the truck wash, and one of those trailers was still positive for PEDv after the washing step,” Hood explains. “But none of those trailers came back positive after either the disinfecting or drying steps.”
Did the Modified Procedure Work?
Hood believes the study shows the modified procedure works. This truck-wash protocol significantly reduces cost and increases throughput at the truck-wash.
But she says it works with a caution. When she followed those trailers out 30 minutes later, almost half of the trailers had some frozen water on their surface.
“Even though we didn’t find any positives, that’s still a caution for producers that if they want to do this exact protocol, they may need to tweak it a little bit,” Hood says. “If there was virus on the trailer still and that disinfectant had frozen, then it would have stopped the action of the disinfectant and in theory, the virus could have survived.”
What’s Realistic for Commercial Swine Operations?
For Ayers, this study drove home three valuable points. Approximately 25% of the trailers transporting market hogs tested positive for PEDv. And just as importantly, if you wash the trailers, there’s a significant reduction in viral load – from 12 positives down to one. Finally, if you disinfect and dry, that resulted in a 100% reduction.
“I think this research demonstrates that if we wash trailers, we can reduce the viral load that we’re spreading across the countryside,” Ayers says. “The research validates what we’ve always known and gives producers a starting point.”
The Maschhoffs wash all their market trailers year-round, he says.
“We’ve done the financial analysis on it, and it pencils out to make sense for us to wash all trailers,” Ayers says. “We’ve seen a reduction in our PEDv breaks, both on the current lot of pigs that may be marketing, but also on the subsequent lot that gets placed afterwards. I think that’s real important to keep in mind as well.”
He says people often focus on the current lot of pigs and don’t want them to break with PEDv. However, he believes it’s even more important not to break the following group of pigs, whether it’s weaned pigs or feeder pigs.
“In our system, it’s something we believe wholeheartedly in,” Ayers says. “We’ve got variation in quality of our washes. A lot of our market hog washes are very similar to what Dr. Hood explained. They’re just a high-volume water wash. Some are disinfected afterwards, and then as we move up higher in our health tiers for feeder pigs or wean pig movements, we do disinfection as well as bio dry or thermal assisted drying.”
He believes this modified procedure could be a good cost-reducing measure for producers who currently are not doing much with their market trailers right now to reduce the viral load across the industry.
