Pathogen Risk in Feed: Research Outlines Roadmap For Future

P0rcine epidemic diarrhea virus (PEDV) opened a lot of eyes in 2013 as the disease devastated many U.S. pork operations. Lessons learned from the introduction of PEDV have helped direct investments in research in the pork industry.

Feed is one of those areas of investment. It’s a unique risk for swine diseases due to the global sourcing of ingredients and the direct access to pigs in high-biosecurity commercial operations, explains Megan Niederwerder, associate director of Swine Health Information Center (SHIC).

Several important research objectives on understanding feed as a risk for swine diseases have been targeted and investigated through SHIC-funded projects and projects co-funded with other funding agencies, USDA, as well as pork production and allied industry companies, including:
1. importation
2. stability
3. transmission
4. mitigation
5. diagnostics
6. field investigations
7. risk assessments

“By generating this cumulative body of knowledge over the last six years, SHIC-funded research has provided valuable data on feed risk to the swine industry as well as outlined a roadmap for investigative steps to target emerging risks for disease introduction,” Niederwerder says in a release. “Feed biosecurity and feed safety, from ingredient sourcing to feed delivery vehicles, are critical components to overall biosecurity plans for the protection of U.S. swine.”

SHIC cited a few examples:

Importation

Research has quantified the volume of certain soy-based products imported from countries with foreign animal diseases (FAD) to define imported soy-products used in feed as a risk for introduction of swine diseases. Findings identified India, Argentina and Ukraine as the countries positive for FAD from which the greatest quantities of soy-based ingredients were imported. SHIC also convened the major manufacturers of vitamins imported from other areas of the world to present information on manufacturing parameters, prevention of contamination post-production and relative risk from these products.

Stability

To determine if commonly imported feeds or ingredients support virus stability, research has characterized the stability of 14 viruses across 12 feed ingredients or products of animal origin when exposed to simulated transoceanic shipment conditions, SHIC explains. Early projects using laboratory quantities of feed ingredients led to interstate transport of bulk feed totes to translate results to real-world conditions. Findings identified soybean meal as stabilizing the greatest number of viruses and identified Senecavirus A (SVA), African swine fever virus (ASFV), and pseudorabies virus (PRV) as being stable in the greatest number of feed ingredients.

“Bringing together the soy commodity organization and processing companies to discuss soy products’ contribution to feed risk garnered support from that industry. Research priorities were identified and addressed by the soybean checkoff association,” SHIC says in a release.

Transmission

To characterize the risk of virus transmission through the natural consumption of contaminated feed, cutting-edge research investigated the infectious dose and volume of contaminated feed necessary to result in infection of pigs with foot-and-mouth disease virus (FMDV) and SVA. Findings confirmed that FMDV and SVA are transmissible through natural consumption of contaminated feed, the research says.

Chemical Mitigation

To determine efficacy of chemical mitigation tools for reducing the risk of feed for swine pathogens, SHIC helped evaluate several different chemical feed additives for their ability to inactivate viruses in feed, such as ASFV, FMDV, SVA, PEDV, and porcine reproductive and respiratory syndrome virus (PRRSV). Researchers discovered medium chain fatty acid and formaldehyde-based feed additives were effective at reducing the infectivity of ASFV in feed ingredients.

Physical Mitigation

To determine efficacy of physical mitigation tools for reducing the risk of feed for swine pathogens, research studied storage time necessary at various temperatures to inactivate PRRSV and SVA contaminated soybean meal. Findings confirmed 30 days of storage at 75°F was effective at reducing the risk of virus infection through consumption of contaminated feed.

Diagnostics

To optimize detection of virus contamination within swine feed, research compared feed sampling techniques in bulk ingredients and nucleic acid extraction techniques to identify protocols which enable the highest detection efficiencies. SHIC says the findings defined an effective bulk sampling protocol and identified a commercially available nucleic acid extraction kit with the highest sensitivity for PRRSV and SVA detection in feed.

Field Investigations

Timely research performed diagnostic surveillance for SVA and porcine deltacoronavirus (PDCoV) in feed and environmental samples from outbreaks associated with feed mills to investigate the role of contaminated feed from feed mills in field outbreaks of U.S. endemic swine diseases. Findings identified feed delivery vehicles as potential risks for disease spread due to detectable PDCoV in truck samples.

Risk Assessment

A quantitative risk assessment modelling ASFV introduction into the U.S. through contaminated corn or soybean meal imports has been completed to calculate the risk of imported feed as a route for ASFV introduction. The assessment included probabilities of ASF virus contamination, inactivation during processing and transport, recontamination and inactivation during customs clearance.

For more information, visit https://www.swinehealth.org/results/