New research is showing that animal feed can carry viruses, including the one that causes African swine fever.
It’s a threat that must be thwarted, Scott Dee, veterinarian and director of applied research for Minnesota-based Pipestone Veterinary Services, told attendees at the virtual 2021 Banff Pork Seminar in January.
“We’ve got to work together,” said Dee. “This is not just Canada, this is not just the U.S., this is all three countries in North America. Our collective goal has to be to keep African swine fever virus out of this continent.”
Animal feed had previously been overlooked as a risk factor until the virus causing porcine epidemic diarrhea began infecting U.S. swine herds in May 2013. But it has since been demonstrated that some feed ingredients, particularly soy-based products, can support the viability of viruses, including the one that causes African swine fever (ASF). This discovery had added significance in 2018, when African swine fever decimated the Chinese pig herd, the world’s largest.
It’s estimated that the number of breeding sows plummeted to 15 million, from 50 million previously (and now stands around 30 million), said Dee. (Parent company Pipestone System provides management services for hog farms and manages a 70,000-sow system in China.)
“The Chinese are very, very concerned about feed contamination. There’s plenty of good information in China that the ASF virus entered farms through contaminated feed.”
And some of that could have conceivably made its way here. Although the U.S. exports tens of millions of tonnes of soybeans annually, it also imports soy-based feed for specialty markets (such as organic feed) or feed additives. In 2018, it imported 104,000 tonnes, with just over half coming from China.
“It’s crazy when you think about it,” said Dee. “Putting our agricultural industry at risk over 104,000 tonnes.”
There’s a financial advantage in importing large volumes of certain feed additives from China, so instead of stopping that practice, he said Pipestone set up a system for amino acids and vitamins that has built-in biosecurity protocols that are audited right from the manufacturing plant in China to warehouses and shipping all along the chain into the U.S.
Other buyers have switched to suppliers in different countries, but that doesn’t eliminate the risk.
Imports from China fell nearly 90 per cent in 2019, with Ukraine replacing China as the top supplier and Russia greatly increasing exports of soy-based feed ingredients to the U.S. But both countries have cases of African swine fever, Dee said.
Contaminated feed and feed ingredients are now widely recognized as likely vehicles for the transport and transmission of viral pathogens. In Canada, restrictions are placed on feed ingredients from ASF-positive countries and the Canadian Food Inspection Agency has established secondary control zones around all national seaports where these high-risk ingredients are received. After arrival, products must be stored under controlled environmental conditions for a specified interval to allow adequate time for viral decay prior to distribution to milling facilities.
Expanding knowledge on the half-lives of viruses found in essential animal feed ingredients has led to science-based protocols in the U.S., which allow these materials to be safely introduced from high-risk countries, Dee said.
This approach is referred to as “responsible imports” and relies on a comprehensive risk assessment process that considers factors such as the need for the imports and whether there are alternative suppliers. It also includes several mitigation methods, including the relatively new concept of “feed quarantine.”
“Clearly there is a growing body of scientific evidence that certain feed ingredients can support the transport and transmission of multiple viral pathogens,” said Dee. “It’s a long list (of ingredients). And there are options now to mitigate this risk.”