Biosecurity programs in commercial swine production typically focus on animal housing and the immediate farm perimeter. However, upstream inputs — particularly feed and ingredient supply chains — represent critical and sometimes under-recognized pathways for pathogen introduction.
Feed is unique among production inputs because it is delivered directly into animal environments and consumed daily. As veterinarians supporting the Carthage System’s 30-plus sow farms, our collaboration with feed mills extends beyond diet formulation. It also includes verification of ingredient sourcing, mill biosecurity design, and delivery logistics to minimize infectious disease risk.
Making feed safer
Modern swine diets include not only major ingredients such as corn, soybean meal and distillers byproducts, but also a range of micro-ingredients — including amino acids, trace minerals and vitamins — that are frequently sourced through global supply chains. Some originate from regions where foreign animal diseases (FADs) not present in the United States, including foot-and-mouth disease, African swine fever and classical swine fever, are endemic.
To mitigate this risk, mills supplying Carthage System farms preferentially source ingredients from FAD-negative regions. When procurement from affected regions is unavoidable, imported micro-ingredients are held in segregated, climate-controlled storage to allow time-temperature inactivation of potential viral contaminants. Inventory planning is structured so incoming ingredients can complete the designated holding period before use.
Feed mitigants are also incorporated during manufacturing, particularly during higher-risk seasons when environmental survivability of enveloped viruses may be extended.
Feed mills themselves operate with internal and external clean-dirty line (CDL) separation, analogous to farm biosecurity zoning. Within the facility, traffic flow and personnel movement are structured to prevent cross-contamination between raw ingredient receiving, processing and finished feed load-out. Externally, physical separation of incoming ingredient trucks and outgoing feed delivery vehicles reduces cross-contact risk. In some mills, traffic lanes and access points are designed so inbound and outbound vehicles never intersect, with only the truck scale shared.
Safety in deliveries
While FAD exclusion remains a top priority, endemic U.S. swine pathogens — particularly porcine reproductive and respiratory syndrome virus (PRRSV), porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus — continue to drive production losses. Feed delivery vehicles moving among farms represent a recognized mechanical transmission risk.
To reduce this risk, Carthage System mills and farms use a structured delivery sequencing model referred to as a biosecurity pyramid. Farms are categorized by health status, and delivery routes are scheduled from highest-health to highest-risk sites to avoid reverse contamination.
Health status classifications are reviewed at least weekly and adjusted as outbreaks occur or sites recover. If logistical constraints require deviation from sequence — for example, urgent delivery to a lower-status farm — the vehicle undergoes full wash, disinfection and downtime before returning to higher-health routes, in addition to routine sanitation protocols.
Seasonal environmental contamination also requires management. Winter road conditions in the Midwest can accumulate organic debris on truck undercarriages that may harbor pathogens. Mills typically require removal of this material before trucks enter load-out areas or pass over delivery pits. Farms may also increase on-site feed inventory ahead of forecast thaw events (“sludge days”) to reduce delivery frequency during high-contamination periods.
The importance of mill–farm relationships
For independent producers, the primary takeaway is the need for structured communication with feed suppliers. Vertically integrated systems with dedicated mills can implement unified protocols more readily, but toll and cooperative mills serving multiple clients can also operate at high biosecurity standards when expectations are clearly defined.
Producers should work collaboratively with their veterinarians, nutritionists and mill managers to establish and verify feed-related biosecurity measures. Within the Carthage System, veterinary teams conduct mill biosecurity audits every 6-12 months to verify compliance and incorporate emerging science and technologies. At minimum, annual review is recommended.
Another risk-reduction strategy involves eliminating porcine-derived animal byproducts in swine diets. Ingredients such as spray-dried plasma, serum and other blood products provide highly digestible protein and energy, but also present significant pathogen transmission risk within species. Carthage System diets use alternative sources to reduce this exposure pathway.
Feed biosecurity is not solely a mill responsibility or a farm responsibility. It is a shared system that requires alignment across the entire supply chain.
