Feed biosecurity must address risk of PEDV transmission
The biosecurity of swine feed is important for producing healthy animals and safe pork. But until 2013, feed was considered a low-risk vehicle for transmitting viral pathogens to swine.
This changed when the highly infectious porcine epidemic diarrhea virus (PEDV) arrived in North America. Feed and feed ingredients faced heavy scrutiny as potential vehicles for spreading the virus, according to Joe Crenshaw, APC Inc. He spoke at the American Association of Swine Veterinarians annual meeting.1
An investigation into how PEDV entered the US was not able to conclusively determine the source. But the investigation reported “contaminated bulk bags were the most likely route of entry,” Crenshaw said.
Spray-dried porcine plasma was associated with early cases of the virus in Canada but later repudiated. Investigations found a low to negligible risk of PEDV transmission through feed or feed ingredients of porcine origin, according to Crenshaw. In addition, a review of research validated the biosafety of spray-dried porcine plasma relative to several swine pathogens, including PEDV.
Feed biosecurity plans crucial
Because PEDV can survive in feed, biosecurity for feed production must consider the risks of transmitting viral pathogens like it, Crenshaw said. Resources are available to help veterinarians and swine producers develop biosecurity plans for internal feed production as part of overall animal-health programs.
The main objective of a biosecurity plan is to identify potential hazards, develop protocols to control the hazards and increase biosecurity awareness. The plans should ensure proper training of staff.
Also important is a verification program that makes sure suppliers of ingredients have adequate programs to control biohazards and contamination. Suppliers should maintain ingredient specifications and show compliance of their biosecurity programs.
Sampling feed ingredients when received is important for reducing the risk of biohazards in a feed mill. Because feed ingredients come in many forms and containers, sampling procedures will vary accordingly. For example, multiple samples must be taken from various locations in a bulk bin or truck and at repeated intervals as a bulk bin or truck is being unloaded.
The sampling for biohazards like PEDV must be conducted with aseptic procedures to make sure samples are not contaminated. This means using disposable latex gloves, sanitized sampling tools, aseptic packaging and sanitary sample containers. Samples with live microorganisms should be refrigerated immediately and transported in insulated packaging to make sure the microorganism does not grow.
Crenshaw also recommended “appropriate diagnostic tools to distinguish if a microbial genome is infectious and can rapidly generate valid results to be used for defensible actions.”
Biosecurity of spray-dried plasma
Since he is employed by a manufacturer of spray-dried animal-blood products for use in feed, Crenshaw also discussed biosecurity procedures used during the product’s manufacturing process. He said good management practices require blood to be collected only from inspected animals that are determined fit for slaughter for human consumption.
At the slaughter plant, a specially constructed system captures the blood and rapidly removes it from the slaughter area to a fully dedicated and enclosed stainless-steel system to prevent contamination. The whole blood or plasma (if separated in a centrifuge) is cooled to 39° F (4° C) within 5 minutes of collection and transported within 24 hours for further processing and drying. All equipment is sanitized at the plant.
Company facilities are dedicated to only processing blood products, with most handling only porcine or bovine blood or plasma. Biosecurity measures control entry to and exit from the plant and facility. Products entering the plant must meet quality standards.
The processing is a highly controlled, computerized process, according to Crenshaw. During spray-drying, the product is exposed to temperatures over 176° F (>80° C) throughout the substance to eliminate certain animal-health risks. Strict biosecurity measures are used throughout the processing plant to ensure sanitary conditions.
Since the PEDV outbreaks, manufacturers of the spray-dried blood products have implemented additional measures for post-drying heat treatment to ensure PEDV does not survive in the product. Plus, a new photo-purification process that is effective against a variety of pathogens, including bacteria and either envelope or non-envelope viruses, is being introduced, he added.
Verifying safe feed supply
Biosecurity measures for the safe production and transportation of the nation’s swine-feed supply are available. But ensuring these measures are used on the more than 50 million tons of feed fed to US swine each year is a daunting task.
At the local level, Crenshaw recommended feed mills and swine producers purchase only consistent and certified feed products from suppliers who have verified biosecurity programs and process controls. This will reduce the need for routine sampling and analyses of every in-bound feed or ingredient.
“Managing the biosecurity of the national feed supply for the swine industry is challenging,” he added. “Commitment by all stakeholders to communicate and collaborate by adopting best management practices for feed biosecurity process controls are crucial for success.”
1Crenshaw J. Process controls and sampling methods currently in place. Feed: Commanding New Focus. 48th American Association of Swine Veterinarians’ Annual Meeting. 2017;6-9.