One of the Most Important Questions Every Pig Farmer Should Ask

(National Pork Board and the Pork Checkoff)

Where does your feed come from? It’s one of the most important questions every pig farmer should ask their feed mill. Although feed biosecurity might not be as talked about in the pork industry, experts agree it should be a fundamental part of everyone’s biosecurity plan. 

Studies have shown African swine fever (ASF) virus can survive in feed being shipped across the globe, but what happens when those feed ingredients arrive in the U.S.? 

Megan Niederwerder, associate director of the Swine Health Information Center (SHIC), says that’s what makes a report recently published in the scientific journal Transboundary and Emerging Diseases so important.

“Historically, we have evaluated ASF stability in various feed ingredients, but it was always using a transoceanic model, which incorporated fluctuating temperature and humidity consistent with global shipment,” Niederwerder says. “Although this provided important information, we had never evaluated ASF stability in feed ingredients upon arrival, or in their country of origin, when held at a constant temperature. For example, could you store feed ingredients in a conditioned warehouse to allow the virus to decay over time? How can we provide those storage recommendations to feed mills and producers?”

Those questions about storage served as the impetus for this study, she explains.

ASF is Sensitive to Temperature
In the published study, the stability of ASF virus Georgia 2007 was determined in three feed matrices, including complete feed, soybean meal and ground corncob particles (corncob carriers). After ASFV contamination, feed matrices were held at three environmental temperatures (cool storage at 40°F, ambient storage at 68°F, and hot storage at 95°F) for up to 365 days. Feed samples were tested throughout the one-year period for ASFV genome detection on PCR and ASFV infectivity on cell culture and in swine bioassay. 

Results demonstrate high stability of ASF virus DNA in feed, with detection by PCR in almost all feed matrices throughout the conclusion of each study, including 365 days after ASFV inoculation when stored at 40°F and 68°F. Infectious ASF virus was most stable in soybean meal, with the virus maintaining infectivity as determined by swine bioassay for at least 112 days at 40°F, at least 21 days at 68°F, and at least seven days at 95°F, she says.

Additionally, feed additives were tested for their ability to reduce ASF virus infectivity in complete feed stored at three environmental temperatures (40°F, 68°F, 95°F). Both medium chain fatty acid and formaldehyde-based feed additives were confirmed to be effective mitigants in tested conditions.   

“One of the most significant findings of this study was the confirmation that, yes, ASF virus in feed is sensitive to heat and survives for less time at higher temperatures,” Niederwerder says. “If you want to speed up the decay of the virus, you could store the feed ingredients in warmer temperatures.”

Another important finding was the confirmation of soybean meal as an ingredient that stabilizes the virus and, in some cases, increases the viability compared to even laboratory media, she adds. This really underscored that specific ingredient as high-risk due to its ability to promote virus stability.

“Although we often times focus on ingredients which pose the highest risk, I also think it's important to highlight that the ASF virus was not as stable in corncob particles and state, ‘ground corncobs appear to pose a lower risk for ASF introduction.’ That's valuable information to have as far as where we focus our efforts and energy on reducing risk,” she explains.

A Top Priority
ASF virus is a primary focus for researchers trying to do everything possible to prevent introduction of this virus into the U.S. In the meantime, this study provides important take-homes for pork producers. 

1.    Look at your feed ingredients and identify which ingredients are the highest risk.
“If you cannot source a high-risk ingredient locally or from an ASF-negative country, before that feed ingredient is actually incorporated into a complete feed diet, consider how and where you could store that ingredient to reduce risk,” she says. “Determine how the ingredient is shipped and then stored once it arrives.”

The study showed ASF virus survives in soybean meal for at least 112 days at 40°F. Niederwerder says that would be the minimum storage time recommended for any high-risk ingredient at 40°F. She recommends at least 21 days at 68°F, and at least seven days at 95°F. 

2.    Is there an opportunity to store my ingredients at a higher temperature? 
“I know that higher temperatures will reduce the virus risk at a faster rate if the ingredients are contaminated, so it could be more cost effective if you store your ingredients in a warmer environment,” she says. 

3.    Consider using a mitigant in feed.
“If your key ingredients are stored at cold temperatures, the use of a mitigant could be considered. In our study, mitigants provided the greatest benefit toward reducing storage time in cooler environments,” Niederwerder says.

Incorporating a multipronged approach is critical when it comes time to reduce risk. Perhaps the simplest thing you can do is determine if your soybean products are coming from a country that is ASF-positive. If so, can you source your soybeans somewhere else, from a less risky country or even locally? 

What Happens Next?
In addition to generating minimum holding time recommendations for three environments and providing producers and feed mills key guidance to reduce ASFV risk in feed, the study helps lead to further areas of study.

Now, researchers are turning attention to the possibilities of baking temperatures to help speed the rate of virus decay. The challenge remains what temperature will still allow the nutrients of the feed ingredients to remain intact, providing nutrition for the pig? 

The other area SHIC is funding is a study about decontaminating feed mills and feed mill equipment.

“Other areas of interest concerning feed biosafety are regarding feed production, mitigation, and movement in the case of a foreign animal disease or African swine fever virus outbreak. We need to continue to provide a safe feed source to US swine should ASF be introduced.” Niederwerder says. 

Feed biosecurity should be considered a fundamental part of all swine biosecurity plans, she adds. “This foundational study furthers our goals toward ASFV prevention and protection of U.S. swine herd health.”

Research was supported by funding from the National Pork Board and the Foundation for Food and Agriculture Research, the State of Kansas National Bio and Agro-Defense Facility Fund, Purina Animal Nutrition, Cargill Animal Nutrition and Kemin Industries.

More from Farm Journal's PORK:

 

PQA Plus Version 5.0 Emphasizes Farmers’ Commitment to Produce the Best Pork

The Swientist Craze: Why Kids Are Lining Up to Learn About Swine Biosecurity

 

 

A Watchful Eye: Updates Announced in APHIS Swine Fever Surveillance Plan

 

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