29 July 2019- According to Dr. Scott Dee, Director of Research, Pipestone Veterinary Services, our awareness of the role feed plays in transmitting viral diseases is extremely new. “The whole idea of the risk of feed as a vehicle for the transboundary spread of Porcine Epidemic Diarrhea Virus (PEDV), was confirmed by our team in 2014. So it’s a very new risk factor that hadn’t really been evaluated.” After his pioneering work showing that viruses could potentially survive transoceanic voyage conditions in feedstuffs and bring infection to farms a world away, the next question, for him, became “well, what do we do about it?”
Dr. Dee wasn’t the only one wondering about this. With the support of the Foundation for Food and Agriculture Research (FFAR), the Swine Health Information Center (SHIC), and feed additives companies including ADM Animal Nutrition, Anitox, Kemin Industries, NOVUS, and PMI Nutrition Additives, he set off to determine whether existing feed additives could help mitigate the impacts of virally-contaminated feed. It was, in the words of FFAR, “one of the first to produce results in a research setting that replicates commercial conditions.” And its findings may resound loudly across an industry which is currently being shaken to its core by a deadly virus.
To be clear, Dr. Dee’s trials are not immediately concerned with ASFv; rather, they introduced PEDv, PRRSv, and Seneca Valley A into feed, and compared the outcomes of pigs whose feed also included commercially available feed additives with those without such “mitigants”. As Dr. Dee explained to Feedinfo, the current round of trials looked at five different additives, one of which was tested at two different inclusion levels. They are planning another round of trials with five or more additives in Q4, for a total of 10 or more products across the project.
What are these additives? Dr. Dee claims to have selected a diverse bunch, rather than relying on ones with a single common mechanism to combat the viruses. All are currently authorized for use in feed for other purposes, including growth performance and gut health; none had a label claim for use against viral disease. “I basically reached out to the American Feed Industry Association and asked the question ‘who’s interested in participating in this new experiment?’ And the companies came forward, they volunteered basically to provide funds and to provide the product for use in our study,” Dee recounts. A large number of potential additives were then screened for in vitro effectiveness, after which the most promising were selected for the current field trials.
The results were striking. First, Dr. Dee claims all of the mitigation additives tested so far appeared superior to non-mitigated feed. Specifically, he says, “what’s really interesting is that in some cases, you can find the virus in the pig, but if the pig is on mitigated feed, you don’t see clinical disease. The mitigants don’t seem to sterilize the feed, but they seem to protect the pigs against the effects, so the pigs don’t get sick, and they grow very well.” In comparison, in the positive control room (pigs consuming virus-positive/non-mitigated feed), he recounts, “it’s really obvious they are sick, some of them die, they grow slowly…it’s really interesting to see the mitigant effect on the clinical presentation of the disease, it seems to really protect the pig against the disease.”
Second, he reveals that the mitigants were “similar to each other’s performance” in having this effect. This is important, he says, because it gives farmers the freedom to choose the option that works best for them. “It looks like the mitigation has benefit, no matter what product is used…Some are priced different, some have different milling requirements, they’re not all the same. My goal in this thing is to get a big long list of effective products that people can use to select [one] that fits their farm or their mill best.”
Of course, over all of this research looms the specter of African swine fever. As Dr. Dee’s lab is not BSL-3 certified, this was outside the scope of his study. However, partnerships are in place to get similar FFAR-funded research underway at Kansas S
tate University, where one of the US’s few laboratories with the appropriate biosecurity levels is located. “I have a colleague at Kansas State named Dr. Megan Niederwerder and KSU has a BSL3 facility where she can work with ASFV. All the information that I learn, I transfer to her, and then she will use it to test against the actual virus.”
Still, Dee is hopeful that useful parallels may still be drawn from the work. He notes that the Seneca Valley A is a similarly sturdy virus, which may live even longer in feed than ASFv does. “The data we get from Seneca [Valley A] virus could be a good predictor for ASFV effect.”
Even further, he believes the research might spur industry action. He tells of his experience presenting to the National Pork Industry Conference this month. “What was interesting in the comments from the audience was… ‘the US national herd should consider widescale application of a mitigant of some type.’ Think about that: covering the entire herd with a feed mitigant to protect it from the risk in feed of multiple viruses. I love that idea, because to me it makes perfect sense. Let’s everybody take whichever one works the best, or whatever one they want to pick, and put it in and ‘blanket the herd’, put a big national insurance policy over the national herd.”
Dr. Dee anticipates the research will likely be published early next year, after tests on the next batch of additives have been completed.
Navigating the risks posed by ASF will be a subject of discussion at both of the upcoming Feed Additives conferences:
Feed Additives Europe, in Amsterdam from September 25-27
Feed Additives Americas, in Miami from November 13-15 (where Dr. Dee himself will be presenting).
Book your tickets today.