The U.S. pork industry will remember the winter of 2014 for more than its erratic weather and frigid temperatures. The cold, unfortunately, provided the ideal environment for porcine epidemic diarrhea (PED) virus to thrive.
Incidents of the disease, which was first detected stateside in April 2013 and has since spread to 30 states, spiked, bringing total losses to more than 5 million piglets.
With an especially susceptible swine herd, 100 percent mortality in nursery pigs and no commercially licensed vaccine available, the U.S. swine industry has been blindsided by the disease. While it is known that pigs are infected via the fecal-oral route, unexplained outbreaks have prompted questions of the possibility of additional vectors, such as feed and feed ingredients, contributing to its spread.
Then, in February 2014, Canada reported its first outbreak, one it directly related to PED virus-positive feed ingredients. This revelation pushed the feed theory into the limelight and upped the urgency amongst all stakeholders.
Stakeholders meeting steers research
On March 19, the U.S. swine and feed industries organized a stakeholder meeting -- which also included representatives from government, academia, ingredient groups, pork producers and the Canadian feed manufacturer and authorities involved in the February outbreak -- to strategize about next steps and to facilitate an open discussion about the virus and the feed industry’s role in containing it.
“We talked about what we know, what we don’t know and how to go forward in a partnership using a collaborative methodology,” says Paul Sundberg, vice president of the National Pork Board. “There wasn’t any finger pointing, there weren’t any denials -- it was more of a forum to figure out how to make progress in containing the disease.”
According to Sundberg, the meeting had two objectives: To develop and refine a research program to help answer the questions about any role that feed may have in transmission; and to define the areas where more information needs to be discovered.
Those research areas include questions about feed ingredients, feed processing and post-processing contamination. “That doesn’t mean that any one of those things is right or wrong,” Sundberg explains. “It means that we need to answer questions about all of them -- to look at the total feed system for pigs -- starting with feed ingredients all the way to the bins on the farm.”
As a result of the meeting, these priorities were established:
- Investigate the effectiveness and cost of treatments that could be used to mitigate the survival of the PED virus and other viruses in feeds
- Conduct contamination risk assessments at all steps within the feed processing and delivery chain
- Develop a substitute for the currently used swine bioassay procedures
- Continue to investigate the risk of feed and other pathways for pathogen entry into the United States
The goal of this coordinated effort is to avoid the duplication of research and hopefully produce rapid results. In late March, researchers submitted their request for proposals (RFPs) to the National Pork Board; funding will be distributed in short order.
Immediate actions to prevent the spread of PED virus
With more questions than answers regarding the feed industry’s role where the PED virus is concerned, what can feed mills do to protect their customers? Here is a collection of the actions every feed mill can take before an official guidance is issued.
1) Ramping up the mill's biosecurity program
PED-infected animal manure can easily make its way from an infested farm to contaminate another site via fomites, i.e. any object -- human or otherwise -- capable of carrying the disease. Since very little PED virus is required to spur infection, all feed mills should immediately implement strict biosecurity protocols to eliminate the risk of cross contamination.
“The feed industry needs to make sure it’s conscious of its biosecurity practices in order to prevent contamination by keeping our mills clean and controlling traffic in and out of our facilities,” explains Henry Turlington, director of Quality & Manufacturing Regulatory Affairs at American Feed Industry Association (AFIA).
Transportation: Moving from farm to farm, feed delivery vehicles become a PED fomite. Ramping up biosecurity in the feed delivery process is the first line of defense against spreading the virus. Feed mills, for example, should wash and disinfect the outside and inside of the vehicle and let the disinfectant dry before moving it to the next site.
Feed deliveries to infected farms should be scheduled on the same day -- no exceptions.
In addition, stress the importance of your mill’s biosecurity program to third-party vendors.
Employees: People are also responsible for moving infected manure. Mill employees should clean their boots before entering the mill.
Delivery drivers should wear disposable boot covers and coveralls every time they get out of the cab on the farm. Before returning to the mill, they should leave their disposable boots and coveralls on the farm and not bring them back into the cab.
Dr. Steve Dritz, Kansas State University veterinarian and swine specialist, takes this a step further by suggesting feed mills create a written plan asking feed delivery drivers not to enter the facility.
2) Risk assessments in the mill
Conduct a risk assessment in the feed mill and on the property to identify the most likely places contamination could happen. Determine where there are the problems -- identify those gaps -- and then focus your efforts on these high risk areas where there is the highest likelihood of cross contamination.
Researchers at Kansas State University plan to intentionally infect test feed in its mill specially designed to contain infectious organisms. The goal is to determine how the virus moves through a feed mill and identify the critical control points.
“From a laboratory perspective, we want to determine if the PED virus is carried over and how it could infect a batch of feed,” explains Dritz. “Hopefully this research can provide some basis for a risk analysis to give the industry a sense of feed’s role in the transmission.”
3) Encourage customer communication
Dr. Lee Johnston, professor in animal science and director of operations West Central Research and Outreach Center, University of Minnesota, urges feed mills to open the lines of communication with their customers. By tracking which farms have experienced PED virus breaks and which ones have not they can tailor their deliveries accordingly.
“When the farm breaks, they should be making a call to their feed mill to say they’re positive,” Johnston says. “I suspect this is probably happening more widespread that it has been before. My advice to the feed millers: If you’re not getting these calls, let them know that you would like to know and then producers will make the decision whether they want to share that information.”
Meanwhile, the USDA is currently considering making the reporting of PED virus cases mandatory.
4) Supplier verification
Feed ingredients have long have been under suspicion as a PED vector. While your mill may have strict biosecurity measures in place, Turlington stresses the importance of knowing if your suppliers are doing the same: “You have to know what your suppliers are doing to limit the risk of ingredient contamination. What are your supplier’s biosecurity practices and how do they ensure their product is safe?”
Do your part
Before new research delivers the final word on what needs to be done to control the spread of the PED virus, the steps feed millers can take to become part of the solution boil down to their commitment to their customers.
“Be aware of what’s happening in your community and recognize that this is a serious disease for the pork industry,” Johnston urges. “[Feed mills] can play a part in helping keep it at bay or play a part in helping spread it. If your customers come to you with requests that look like they’re just hoops to jump through -- take them seriously.”
Bottom line: The feed industry has the responsibility to ensure the safety of the products it delivers.
“We must do our part to help control the disease and I’m confident that responsible feed manufacturers are doing those things,” Turlington says.
FEED INGREDIENTS: PED virus vector?
The elephant in the room is whether or not PED virus-positive porcine products, i.e. pork plasma, meat and bone meal, blood meal, animal protein, are responsible for the rapid and far-reaching spread of the disease.
The truth is: the data is inconclusive. While polymerase chain reaction (PCR) tests can identify the DNA composition of the virus in porcine byproduct, a PED virus-positive result doesn’t necessarily mean the virus is active. In turn, this doesn’t necessarily mean it’s inactive either. Researchers and industry are the first to admit the lack of conclusive testing presents more questions than answers.
“One of the challenges is that you can test materials for the genetic presence of the virus, but you can’t determine if the virus is alive or active,” explains David Fairfield, vice president of feed services, National Grain and Feed Association (NGFA). “Then, in some of the bioassay testing that’s been done, it’s been inconclusive or that testing hasn’t been able to be replicated. There are challenges in terms of identifying maybe a more robust protocol to be used in bioassaying, e.g. trying to better standardize the bioassaying to provide more consistent results. All these areas come in to play to better identify where the disease is at and how it’s being transmitted.”
According to the National Renderers Association, the PED virus is very susceptible to high temperatures and should be destroyed during animal protein processing -- and, subsequently, during pelleting in the feed mill. However, this assurance hasn’t prevented swine producers from reformulating their diets to exclude these ingredients.
“The biggest challenge for the feed and ingredient industries right now is that we do not have a good verification method to confirm [porcine plasma] is completely safe -- and it’s having a big impact on swine production,” Turlington explains. “Their costs are going up because they’re taking out an effective ingredient that helps with the animal’s growth. The removal of plasma is a tough decision, but companies are doing it to protect their investment and their industry.”
To date, the U.S. pork industry has not come out to recommend producers removing plasma from swine diets, leaving the decision to the producer, their veterinarian and nutritionist to decide what’s best for their pigs and their farms.
“Every time you remove something from a formula there’s an economic cost,” Fairfield says. “Companies are weighing those decisions on an individual basis.”
In the meantime, the feed industry plans to conduct additional testing to gather the scientific data necessary to confirm the safety of these products to restore customer confidence.
