Working with funding provided by the Swine Health Information Center (SHIC), Dr. Scott Dee and his team at Pipestone Applied Research have been studying the risk of virus movement in feed.
SHIC noted in its May newsletter, as well as in a post prepared for the American Association of Swine Veterinarians, that early work was all completed in the laboratory and confirmed the survivability of porcine epidemic diarrhea virus (PEDV) in feed as the vehicle for transmission and transport.
More recently, Dee developed a demonstration project to reproduce the results found in lab studies under real-world conditions, SHIC said. The report summary said the results indicated the presence of viable porcine reproductive and respiratory virus (PRRSV), Senecavirus A (SVA) and PEDV in both conventional and organic soybean meals, while viable SVA was recovered from all five feed ingredients tested: conventional soybean meal, organic soybean meal, lysine, choline and vitamin A. In contrast, survival was limited in the vitamins and amino acid ingredients.
While all results achieved in the lab setting were valid, Dee noted a need for more information, particularly from producers and government agencies, beyond a lab setting, the SHIC newsletter said.
"We wanted to expose the viruses to as many environments as possible in the continental U.S.," he explained. "This was like an actual commercial journey."
For the current SHIC-funded project, feed spiked with viruses was loaded into containers on a truck and driven all around the U.S. The trip lasted 21 days, involved 107 hours of transport and crossed 14 states, covering approximately 6,000 miles. From Minneapolis, Minn., to Iowa to Colorado to Texas, across the southern coast, up the Eastern Seaboard and back to the Midwest, the trip exposed the virus-spiked feed to mountainous, western, Gulf Coast, eastern, New England and midwestern environments, SHIC said.
Upon the truck's return to Minnesota, the feed samples were tested. SVA was found in every feed ingredient evaluated. Dee noted that this reflected what had been seen previously in the lab: that SVA — a surrogate of foot and mouth disease — survives and is stable in feed ingredients. The results showed that PEDV and PRRSV survived in feed as well.
This demonstration also confirmed lab results showing that soy-based products are supportive of viruses: Both organic and conventional soybean meal were included, and all viruses lived well in each, SHIC said. In the end, results from the lab were reproduced in real-world conditions.
SHIC said it is important to note that this demonstration project was conducted with great care for the viruses included in the test ingredients. Samples were very well contained in boxes securely loaded in the trailer without a risk for spills. There was no other cargo in the trailer, and the only stops made were for fuel and overnight rest.
"We wanted to protect the sanctity of agriculture," Dee said. "These were not foreign animal diseases. We talked to the Board of Animal Health director and [U.S. Department of Agriculture]. If we were managing the demonstration as described, they were perfectly fine with it."
The amount of feed in this demonstration was small, just 30 g per test, which allowed the entire quantity of feed to be tested at the conclusion of the journey so there were no false negatives, SHIC reported. Because this was a proof-of-concept project, a larger-scale demonstration is next on Dee's agenda for this fall.
"We're going to do this whole thing again in November using one-ton totes of organic and inorganic soybean meal," he said. "We will get away from the 30 g amounts and into a representative volume producers are dealing with all the time in tons." When these ingredients return, sample testing will be completed. The same route, viruses and feed products will be used. "This helps bridge the gap from lab to the real world," Dee concluded.
According to SHIC, Dee anticipates that the results will help people gain more confidence in the evidence that viruses can live in feed under a commercial shipping event.
As the world deals with the COVID-19 pandemic, SHIC continues to focus efforts on prevention, preparedness and response to novel and emerging swine disease for the benefit of U.S. swine health. As a conduit of information and research, SHIC encourages the sharing of its publications and research, which may be forwarded, reprinted and quoted freely. SHIC is funded by America's pork producers to fulfill its mission to protect and enhance the health of the U.S. swine herd. For more information, visit http://www.swinehealth.org, or contact Dr. Paul Sundberg at firstname.lastname@example.org.