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Updated Feed Holding Time Calculations Inform Biosecurity Processes

February 5, 2020 — Paul Sundberg

Studies have shown the theoretical ability for swine viruses to be transmitted through feed and feedstuffs. Ongoing research caused the Swine Health Information Center (SHIC), the National Pork Board, the National Pork Producers Council, and the American Association of Swine Veterinarians to offer updated and revised information for feed holding times to mitigate virus transmission. Feed component holding times could be one tool used in conjunction with other mitigations to enhance feed safety. Sourcing feed components from regions or countries of the world that don't have ASF, or other diseases foreign to the US, will also negate potential risk.

The Institute for Feed Education and Research (IFEEDER), the public charity of the American Feed Industry Association, helped fund the initial research providing the best understanding of viral survivability in feedstuffs and details for mitigating risk to domestic herds via holding times, based on using Senecavirus A in the model.

The initial estimations, which were calculated in October 2018 then updated the first time in May 2019, now reflect new information from work done on African swine fever (ASF) half-life. Based on the conditions of transpacific shipment from Asia, the following table displays the mean holding times calculated to provide 99.99% ASF degradation at 54 degrees F (average).

Mean Holding Time for 99.99% ASF Degradation at 54 degrees F Avg. 1

Average 95% Confidence Interval - Lower 95% Confidence Interval - Higher
Conventional SBM 125 days 113 days135 days
Organic SBM 168 days 150 days186 days
Choline 155 days 142 days168 days

The information shows holding times details for general informational and educational purposes. They should not be considered as to be recommending or advocating any specific course of action. This information will be consistently reviewed and updated for the benefit of the US swine industry.

Complete information on the research leading to the holding time calculation is posted on the SHIC website. SHIC also provides information on questions producers should be asking their feed suppliers as part of their biosecurity protocol.

1Stoian, A., Zimmerman, J., et al. Half-Life of African Swine Fever Virus in Shipped Feed. Emerging Infectious Diseases. 2019;25(12):2261-2263. https://dx.doi.org/10.3201/eid2512.191002.

Funded by America's pork producers to protect and enhance the health of the US swine herd, SHIC focuses its efforts on prevention, preparedness, and response. As a conduit of information and research, SHIC encourages sharing of its publications and research for the benefit of swine health. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Paul Sundberg at psundberg@swinehealth.org.

Paul Sundberg, Executive Director, Swine Health Information Center