Feed delivery and swine biosecurity: what studies of mills, trucks, and drivers have found

Why feed delivery gets attention

Farms receive feed on a regular schedule, and the trucks that bring it travel between farms. In a pilot study of 40 feed-truck drivers in Ontario, Canada, drivers recorded 2,202 farm visits over the winter of 2013, about three farms a day on average, with as many as ten in a day (Bottoms et al., Canadian Veterinary Journal, 2015). Each of those stops links one site to the next.

US guidance reflects that concern. The Secure Pork Supply plan, a voluntary preparedness plan for US pork producers, recommends that deliveries be made to a designated area away from animal buildings when possible. It also recommends recording deliveries and other movements onto the site in a log (Secure Pork Supply, Biosecurity Information Manual). The plan has since dropped the term "perimeter buffer area," but it keeps the same idea of controlled zones (Secure Pork Supply, summary of updates).

What has been found on feed trucks

US feed mills

A 2016 study sampled the environment at 24 US commercial feed mills that delivered feed to farms infected with porcine epidemic diarrhea virus (PEDV) or porcine deltacoronavirus (PDCoV) (Greiner, Journal of Swine Health and Production, 2016). As summarized in a later review, a small share of samples (under 5%) from truck foot pedals and other mill areas, such as bulk-ingredient pits and office floors, had detectable virus genetic material (Shurson et al., Animals, 2023).

A US outbreak investigation

In November 2020, researchers investigated PDCoV outbreaks at three breed-to-wean sites in the Midwest, along with the two feed mills that supplied them (Elijah et al., Journal of Swine Health and Production, 2022). At one mill, PEDV genetic material was found on a feed truck's floor and pedals and on its steering wheel and dashboard. At the other, PDCoV genetic material was found on a truck's steps and in its cab, though only at the study's more sensitive detection cutoff. On the farms, PDCoV genetic material turned up on feed bins and on spilled feed near bins.

The authors concluded that they found no evidence that feed or feed delivery caused these outbreaks, and that the specific route of transmission was unknown. They still noted that people and vehicles can carry pathogens. They also pointed out a gap in the records: the mill's delivery records showed dates and stops, but not the diet delivered or the bin it went into. They recommended detailed records for all feed deliveries.

An international example: African swine fever in Vietnam

Outside the US, a 2019 investigation of a feed manufacturing and swine production system in Vietnam, in an area where African swine fever virus (ASFV) was circulating, sampled feed, mill surfaces, and vehicles (Gebhardt et al., Transboundary and Emerging Diseases, 2022). Of the seven vehicle samples that tested positive for ASFV genetic material, six came from feed-delivery truck cabs and one from the wheels. That was 7 positives out of more than 1,000 vehicle samples. In response, the company began disinfecting truck cabs, added high-pressure washing of truck exteriors, and set a policy that delivery drivers don't get out of the vehicle. ASF has never been found in the US, so this setting is quite different from US conditions (USDA).

What drivers actually do on the farm

The same Ontario pilot study tracked driver behavior. Drivers entered a barn on 7.2% of farm visits, and they wore their own boots in the farmyard on 72.3% of visits (Bottoms et al., 2015). Drivers asked to wear clean boots did so on 45.0% of visits, compared with 9.7% for the control group. One reason was practical: all three drivers who tried treaded disposable plastic boots said the boots were unsafe and that they wouldn't keep using them.

A related US study looked at livestock trailers rather than feed trucks. Among 575 trailers sampled at six harvest plants in 2013, 6.6% were contaminated with PEDV when they arrived. Another 5.2% of the trailers that arrived clean became contaminated during unloading, and that was more likely when plant staff stepped into the trailer (Lowe et al., Emerging Infectious Diseases, 2014). The authors suggested that simple measures, such as having drivers stay on their trucks, could help limit spread.

What producers and feed companies recommend

In an Ontario study, 21 feed-company staff (managers, drivers, and dispatchers) and 15 swine producers suggested and rated biosecurity measures for feed delivery on a 1 to 5 scale (Dewey et al., Journal of Swine Health and Production, 2014). Some of the highest-rated measures involved keeping delivery staff out of the barn:

• "Don't allow feed-company personnel to enter the barn for any reason" rated 4.48 for disease control, 4.74 for ease, and 4.91 for economic feasibility.
• Giving drivers a container to leave the mill order without going near the barn rated 4.32, 4.95, and 5.00.
• Planning routes so high-health herds are visited first rated 4.65 for disease control.

Participants also raised the idea of retrofitting bins so a driver could open them remotely without leaving the cab. They rated it 3.28 for disease control but only 1.33 for ease and 1.39 for economic feasibility. In other words, when the study was conducted in 2012, participants saw remote bin opening as useful for biosecurity but hard and costly to put in place. The authors noted that participants may have been operations already doing well on biosecurity.

US and international differences

• Disease status: ASF has never been detected in the US, while studies like the Vietnam investigation took place where ASF was actively circulating.
• Guidance: US producers can use the voluntary Secure Pork Supply plan. Other countries have their own frameworks, so recommendations and terminology differ.
• Driver studies: much of the detailed research on driver behavior comes from Ontario, Canada, in winter. Results may differ by region and season.

What this means in practice

Across these studies, a few practical themes come up again and again. Keep delivery people and vehicles away from animal areas. Make footwear and other protective measures practical enough that drivers actually use them. And keep delivery records detailed enough to be useful in an investigation, including which bin was filled. Your veterinarian and your site's biosecurity plan should guide the specific steps for your operation.