Wallaces Farmer

It's unknown how PEDV entered the United States.

July 25, 2017

3 Min Read

Feed and feed ingredients have faced heavy scrutiny as potential vehicles for spreading the highly infectious porcine epidemic diarrhea virus, according to Joe Crenshaw, APC Inc., who spoke at the American Association of Swine Veterinarians annual meeting.

An investigation into how PEDV entered the U.S. 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.

Feed-sampling methods

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.

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.

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 39F 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.

During spray-drying, the product is exposed to temperatures over 176F throughout the substance to eliminate certain animal-health risks.

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. 

Source: Zoetis

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