Canada,” he explains. “Since March 2019, Canada has estab- lished import secondary control zones and permits for im- ports from countries with ASF, and the CPC has provided time and temperature recommendations for producers.” Dr Dee is happy to see that the CFIA took all the research seriously and has put many measures in place. “Here, the pork industry and feed industry have adopted some of the same measures,” he says, “but I would like to see a national government-led pre- vention and control programme to address viral disease pres- ence and transport in feed, similar to what is in Canada.”
Feed additives Building on findings showing virus survival in feed, scientists have been studying the capacity of feed additives to destroy viruses. Dr Dee and colleagues at South Dakota State Universi- ty did a study of this in 2019 but it hasn’t been published yet. They found that titers of the four viruses tested (Senecavirus A, PEDv, PRRSv and Bovine herpesvirus type 1) were reduced by the presence of additives that contain a blend of medium chain fatty acids. Specifically, they found a strong anti-viral ef- fect from a product containing a blend of organic acids and an analogue of the amino acid methionine (analogues of this amino acid, HMTBa and HMTBa-Ca, are authorised feed addi- tives in the EU). At the start of May, Dr Dee and his colleagues also submitted a study for publication on the anti-viral effects of various commercial products on Senecavirus A, PEDv and PRRSv in feed. “There are several types of products,” says Dr Dee. “Some contain short, medium and long-chain fatty acids,
organic acids either individually or in blends, and essential oils. A lot of these products are a blend of many things.”
Looking forward Looking at all the research that’s been done, Dr Dee says that on the whole, soybean-based feed ingredients such as soy- bean meal have consistently been found to be very protective of viruses. “We’re not sure if it’s due to the high protein con- tent or another characteristic, but we in the US are still im- porting soybean meal from China, Russia and the Ukraine, which are all ASF-positive countries and that’s crazy,” he says. “In any ASF-positive country, there is the chance of cross-con- tamination through things like feed spilling on the ground and then being scooped up and bagged. Import of that par- ticular ingredient from those countries should be stopped or a national programme like what Canada has, where this would be kept in a holding area and tested and treated, should be put in place. Yes, feed mills are doing this but we can’t be sure they are all doing this, and a national govern- ment-led programme would be best.” In Dr Brockhoff’s view, the most important thing feed mills can do to reduce risk of transmission of viral diseases through feed is, when possible, to buy ingredients from countries that aren’t infected with major diseases. “The Canadian pork industry right now has to import a variety of vitamins from China as we can’t get them anywhere else,” he says, “and it’s an extremely low-risk ingre- dient in terms of viral disease, but the packaging for anything can be a risk.”
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