Links in the feed processing and delivery chain identify disease prevention challenges and opportunities.
Biosecurity programs define the procedures and processes put in place to keep pathogens out of a hog operation and/or the expression of a pathogen that has slipped in.
The pork industry has made tremendous advancements in understanding biosecurity risks. A critical component of biosecurity risk management is pathogen introduction through fomites such as corn, soybean meal and feed delivery trucks.
Fortunately, corn and soybean meal aren't identified as a frequent source of pathogen introduction. Thus, the primary focus of feed biosecurity programs is on the mechanical transfer of pathogens via vehicles and personnel.
Scott Dee, DVM, and colleagues at the University of Minnesota, in a paper published in 2002 in the Canadian Journal of Veterinary Medicine, “Mechanical Transmission of Porcine Reproductive and Respiratory Syndrome (PRRS) Virus Throughout a Coordinated Sequence of Events During Cold Weather,” clearly demonstrated that PRRS virus can be transferred via contaminated snow. It is quite heartening, however, to note that with good biosecurity management, introduction of PRRS through feed and feed transport is very low.
Why Is Biosecurity So Tough?
I often ask myself this question. The simple answer is we operate in a dynamic, biological system in which pathogens can survive and be transferred. If we review all of the links in the chain, it's easy to see that management of this risk is critical to protecting swine herds.
It is often said that biosecurity is only as strong as the weakest link. When we list all of the activities at a feedmill and delivery system, we recognize the challenges, including:
Within mill cross-contamination;
Delivery personnel; and
Feed ingredients are managed by procuring grain from non-pig producing farms or grain that is not stored in close proximity to pigs on the farm. Today, that is relatively easy to manage because of the increasing size and specialization of grain operations. Grain should be transported in trucks that don't haul pigs. This is much easier to manage as transport of grain and livestock have been segregated; therefore, this requirement usually is not a burden for grain suppliers.
Soybean meal heat processing eliminates viral pathogens and, thus, manages the risk from cross-contamination of this ingredient from transport vehicles at the mill unloading bay. Mills with separate incoming-ingredient unloading bays and a separate out-loading finished-feed bay help minimize the truck transport crossover risk. In addition, feedmill personnel should not care for pigs themselves.
The system should have a pyramid flow of feed deliveries, either as a designated separate transport or in a sequence where feed is first delivered to multiplication sites, then to breed-to-wean, and last to wean-to-finish sites.
Any time that flow changes are made, feed trucks should be washed, disinfected and externally dried prior to moving back up the pyramid. The location should always have a separate pyramid and delivery trucks.
The majority of farms receive meal or pelleted feed, except for the transition or first nursery diet. If bagged feed is delivered to the farm, it should be delivered all at one time. Bags should be transported in closed-side containers to prevent road contamination or in a separate, designated delivery truck.
During the winter, it is impossible for feed transport vehicles to avoid dirty roads and possible contamination. Thus, once feed transport arrives, there are some basic procedures to follow:
Transport driver must put on external farm boots that are located for easy access or plastic boot covers must be used when the driver exits the cab.
Transport driver must not enter the office at the farm except in the case of an emergency. Invoices are left in a designated area, most commonly in mailboxes attached to the bin leg or just outside of the office.
Bin lids should open and close from the ground.
Any bagged feed deliveries enter only through a disinfection chamber. Bagged feed is dropped in a designated area, again avoiding direct entry into the office area by the transport driver.
We often talk about feed delivery outside the perimeter of a site. But this is not practical due to the volume and the location of the feed bins, so the feed transport must use other procedures to minimize risk of contamination.
Practically speaking, maintaining absolute biosecurity on a breed-to-wean farm is difficult because the transport driver must exit and return to the truck several times, depending on diet and bin capacity. The best procedure is for the driver to wear farm boots and then a set of boot covers so when he/she reenters the cab, boot covers are placed on the shoes or boots.
Another common option is to have disposable floor mats in the truck. When the driver exits the site, the disposable floor mats are left in a designated trash container with the farm-specific boots or boot covers.
Feedmill staff and transport drivers should attend at least biannual biosecurity educational training established with a veterinary clinic. This training is held at the feedmill and attendance is required for all new drivers. Don't expect the transport group to provide this education.
The biannual meetings reinforce basic biosecurity procedures and policies, answer questions, and provide a practical understanding of procedures.
In summary, the feedmill and transport are key components to herd biosecurity. Biannual feedmill audits, coupled with educational meetings, both with the feedmill and the farm staff, are helpful in achieving compliance.
About the author: Joe Connor, DVM, is co-owner and a partner in Carthage Veterinary Services, Ltd., located in Carthage, IL.