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National Hog Farmer is the source for hog production, management and market news
January 13, 2023
When Cassandra Jones describes African swine fever to her students, she often refers to it as the "armored tank of viruses."
"What that means from a scientific perspective is that it's a very large virus," says the Kansas State University Department of Animal Sciences and Industry teaching coordinator and professor. "It's an enveloped DNA virus, and its envelope helps it survive for long periods of time, which is partly why it is causing a lot of devastation within the swine industry."
During a recent K-State Agriculture Today broadcast, Jones detailed the latest research her team has conducted in an effort to prevent entry of the ASF virus through feed or feed ingredients.
"It's been shown that some very stable viruses, like Senecavirus A or Seneca Valley virus, can enter a country and cause disease through imported feed or ingredients. We want to make sure that the same does not occur if we import ingredients from an ASF-positive country," Jones says. "But at the same time, it's not practical for us to just stop all imports of all trade from any country that is ASF-positive."
She says much of their research is focused on "what are the biggest elephants to address."
"While there are many ways that ASF can enter a naïve population, our expertise is to understand that risk in feed. While feed-based transmission risk is low compared to some of the other routes, the possibility still exists and our research team tries to understand ways to prevent that from occurring. To address this, we ask ourselves, 'What are the categories of ingredients that are considered to be high risk? How can we mitigate that risk? How can we prevent that from entering the United States in the first place?'" Jones says. "But also, we are doing quite a bit of preparation work as well, so that if it were to enter the U.S., regardless of the route, we can take steps to make sure ASF is not accidentally spread throughout the feed supply."
While most sow farms in the United States having strong biosecurity protocols in place, Jones says those same steps don't always carry over to handling feed.
"Our industry has excellent farm-to-farm biosecurity. To move from one sow farm to another, you typically must shower and have downtime between sites. However, we frequently deliver feed to different sites on the same day using the same truck without sanitation steps between deliveries. While we control farm-to-farm risk, we have a gap in farm-to-feed mill-to-farm biosecurity," Jones says.
She says studying ASF can be exciting at times because there's so much new information to discover, but also frustrating because there's no standard way to conduct that research.
"Our graduate students need to be a bit of scientific MacGyvers because many times we have important research questions to answer, but there are no standardized methods for how to answer the question. We are developing the methods for collecting samples and the assays for feed and environmental samples as we go – somewhat inventing the science of how to collect, analyze and interpret the data," Jones says. "I am trained as a swine nutritionist, where we have reliable assays for things like quantifying the energy or lysine level of an unknown ingredient. When we deal with feed safety research, we might collect samples with an unknown viral presence, but then try to analyze them with an assay that has never been used for that sample type. If we get a negative result, we don't usually know if that means there is really no virus present, or that there is virus, we just can't detect it using our current methods.
"We're thankful for our partners in diagnostic labs that help us modify their standardized procedures for analyzing virus in blood or tissues so we can get some type of answer, but when both the sample and assay are variables, we are often left not knowing how to interpret results. While it's frustrating, we know the industry needs us to make progress in this area, so we try to learn from others and fill in the gaps. For example, most of our environmental sampling research is based on things we learned from the human food and pet food world as they try to control pathogens during manufacturing. We have also made big scientific leaps based on applying concepts that we learned are working in Southeast Asia. We've been watching what works and doesn't work to control ASF there, then try to bring that learned to controlled research back here in the U.S. using containment facilities."
For example, the team recently worked with a sophisticated pork production system in Vietnam that was in the middle of a pig dense region in the country and had been riddled with African swine fever virus.
"We help them identify where to collect environmental samples and how to interpret the results. That data helped us better understand why some sites had not broken with ASF while others had. In one case, the production system was doing a great job sanitizing the exterior of feed trucks, but the inside of the trucks was frequently contaminated. Drivers could potentially spread ASF from their shoes from one site to another while they were opening and closing feed bins during deliveries. The feed and the outside of the truck was clean, but we needed to understand how to sanitize the interior of a truck cab. That helped us identify a good research question that we then bring back to the United States and could research here in Manhattan under controlled conditions," Jones says.
Much of that work is conducted at the O.H. Kruse Feed Technology Innovation Center as well as the Biosecurity Research Institute at K-State. While a majority of their research revolves around feed, other studies have focused on fomites and delivery.
"We actually purchased some salvage truck cabs from a junk yard in Kansas. It was one of the more memorable expense account justifications I have submitted," Jones says.
The salvage truck cabs were then brought into a controlled laboratory environment, contaminated with porcine viruses, and evaluated to see if was possible to get rid of the contamination using varying levels of practicality.
"We all want to do something that would be as practical as possible, but at the same point we want that virus to be destroyed," Jones says. "And so we did things as low and as minimal as just having overnight downtime of the truck cab, to spraying the inside with a garden sprayer that had different types of sanitizers, to using chlorine dioxide pouches to see what is effective and practical. That data will help us so that if we have producers in a similar situation, we can provide science-based recommendations for managing the issue."
By studying the virus spread in feed manufacturing, and its survival in feed or ingredients over time, Jones says the research team hopes to answer "how much virus does it take to actually make a pig sick?"
"Because similar to cold and flu season, you may be exposed to a kindergartner that has the sniffles and you may not get sick, but your grandmother might," Jones says. "We all have kinds of different immune systems and some of those are more sensitive than others, and so likewise we're trying to understand what are factors that impact how much dose of a virus in feed it takes to cause disease within an animal."
The team is also trying to determine how to effectively mitigate that dose as well. Recent research has shown that some feed additives can prevent some contamination. The team has also investigated thermal processing and sanitation procedures at the feed mill. Jones says it's important to note while this type of research is conducted in a controlled setting, the team is asking practical questions and using practical equipment.
"As someone who works at a university and cares passionately about the future of animal agriculture and our producers, I try to think about what do the producers need our team to work on. What are the most important things that I can do to help those producers?" Jones says.
And the K-State research team is always looking for more members to join their team.
"We're always looking for research partners. Our biggest learnings have come when producers have shared their challenges and opened their doors to us as researchers. We rely on the industry to help us understand what the problems in the field are, then we can work to resolve them using controlled research and applying those results together," Jones says. "And so we welcome the opportunity for our team to conduct biosecurity assessments and help identify where there might be gaps on your own farm or within your production system. That experience helps us better address industry challenges."
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