Ames, Iowa — In preliminary findings, a study conducted by Pipestone Applied Research and South Dakota State University shows the potential for porcine reproductive and respiratory syndrome virus (PRRSV) and other viruses to contaminate and survive in feed ingredients, including soybean meal (SBM) and dried distillers grains (DDGs). The study is based on a model simulating the transboundary movement of contaminated ingredients that was developed to identify “high risk combinations” of viruses and feed ingredients. The entire white paper is available at http://www.swinehealth.org/pathogen-transmission-white-paper/.
The Swine Health Information Center (SHIC) is interested in discovering potential risks to the US pork industry and has provided significant funding for this ongoing work. The SHIC Swine Disease Matrix was used to identify target viral pathogens for evaluation in the study. Researchers used “surrogate viruses” in some instances which allowed study of closely related and structurally similar viruses.
This research examined multiple viruses for their ability to survive under shipping conditions coming into the US. Preliminary data indicate the survival of viruses and surrogate viruses including the Seneca Virus A (surrogate for FMDV and of interest itself), Bovine Herpesvirus-1 (surrogate for Pseudorabies virus), and PRRSV (using PRRSV 174) during the 37-day study period. Ingredients frequently supporting virus survival include SBM, lysine, choline, and Vitamin D, and, in some cases, DDGs. Other products were not shown to consistently support viral survival during the 37-day study period. In the process, a subset of viruses has also been recovered from pork casings and different kinds of pet food. None of the viruses survived the 37-day incubation period in the absence of a feed component matrix.
These results suggest a subset of contaminated feed ingredients could serve as vehicles for foreign animal disease, other transboundary introduction in the US and possibly circulation of viruses within the US. In particular, the PRRSV data may provide new insights and areas of further study on the role of area spread.
Further mitigation research has already begun. This process will include testing of a variety of feed additives that might be able to neutralize these pathogens when added to feed during milling or other processes that may help mitigate risk.
Heat treatment during corn processing into DDGs and soybean conversion into SBM should neutralize pathogens present on the corn kernel or bean prior to processing. However, research at Kansas State University has shown the potential for porcine epidemic diarrhea virus (PEDV) contamination of feed during the milling process if PEDV is present within the feed mill emphasizing the need for feed mill biosecurity plans (https://www.aasv.org/shap/issues/v24n3/v24n3p154.pdf). Although, more information is needed about oral viral infective doses to accurately assess risk.