A journey over land and sea may not keep animal diseases away.
Researchers from South Dakota State University, Pipestone Veterinary Services in Minnesota and Kansas State University found that seven of the 11 animal viruses tested can potentially survive the transglobal journey from Asia or Europe to the United States in at least two commonly imported feed ingredients. The scientists examined virus survivability in 11 imported feed ingredients and products by replicating the environmental conditions in shipping containers.
“The findings of this study show that feed biosecurity should be a major priority for pork producers and ultimately, the livestock industry,” said assistant professor Diego Diel, who led the SDSU team. Scott Dee, director of research at Pipestone Veterinary Services, said, “For the first time, we have data to support that certain feed ingredients are risk factors for moving viruses between farms and around the world.”
Diel and his team at the South Dakota Animal Disease Research and Diagnostic Laboratory assessed the ability of 10 viruses to survive the 37-day journey from Beijing, China, to Des Moines, Iowa.
Kansas State University, which has a Level 3 biosecurity laboratory, evaluated the ability of African swine fever virus to survive the 30-day trip from Warsaw, Poland, to Des Moines. The Iowa destination was chosen because ingredients are mixed at a feed mill in Des Moines and then distributed to swine farms in the Midwest.
In previous work, Dee and ADRDL researchers discovered that porcine epidemic diarrhea virus (PEDV) can survive the simulated trip from Beijing to Des Moines in five feed ingredients—vitamin D, lysine, choline and organic and conventional soybean meal.
The researchers are now looking for cost-effective ways to mitigate this risk through continuing support from Swine Health Information Center.
Identifying high-risk ingredients
Dee worked with a colleague at the Lincoln Memorial University College of Veterinary Sciences to expand the list of ingredients beyond those in the PEDV study. The researchers added soy cake and dried distillers grain solids (DDGS), moist and dry dog food and moist cat food. The use of feline calici virus and canine distemper as surrogate viruses further supported inclusion of these ingredients, he explained.
More than 47,000 tons of imported feed ingredients arrived in San Francisco from China in 2016, according to the International Trade Commission Harmonized Tariff Schedule.
Six viruses survived in conventional soybean meal, while only two did so in organic soybean meal. Though the researchers don’t know what accounts for this difference, Diel said preliminary analysis showed the organic soybean meal had a higher fat content and lower protein content.
Conventional soybean meal is treated with hexane, while the organic soybean meal was not, Dee explained. Because of the processing method used, the organic meal tested had a high fat content and lower protein level. “Those ingredients with higher protein levels seemed to be more conducive to virus survival,” he said.
Four viruses survived in soy oil cake, which is imported from China in the largest quantities of any of the ingredients evaluated. Only two viruses survived in DDGS, which ranks second among imported ingredients.
Four viruses survived in sausage casings. The amount of this processed product returning to the United States has quadrupled from 2012 to 2016.
“We all need to consider the implications of this research and then to understand if this potential transport could lead to transmission to animals and what we need to do next,” Sundberg said. “We must work together with government agencies and the feed industry to protect U.S. meat protein agriculture.”