tested were effective in reducing the survival of PEDV as compared to controls [30]. As mentioned, rice hull flushes treated with formaldehyde or medium chain fatty acid blends resulted in the reduction in the of detectible RNA present after mixing a batch of PEDV-positive feed [24]. In regards to the elimination of PEDV from a contaminated animal feed manufacturing facility, the combined application of a quaternary ammonium-glutaraldehyde blend cleaner, followed by a sodium hypochlorite sanitizing solution, along with a heat facility heat-up to 60°C for 48 hours was effective at reducing PEDV genomic material, but did not completely eliminate it, demonstrating the residual risk of this virus at the feed mill level [31].


Strategy 4: Storage With the generation of new knowledge on viral half-life in feed, the application of a “Responsible Imports” approach has been adapted across the US industry [32]. Responsible Imports, a science-based protocol to safely introduce essential feed ingredients from high-risk countries, is based on the following principles: Necessity: is importation of the ingredient an absolute necessity? Alternatives: can the ingredient be obtained from a country free from foreign animal diseases? Virus: which virus is causing the concern? Viral half-life: is there published information on the half-life of the virus in the designated ingredient? Transport time: what is the projected time for delivery of the ingredient from the source to its destination? Viral load: are there safe products that can be added to the ingredient to reduce viral load during transport? Storage period: is there published information on storage time and temperature that will eliminate residual virus from the ingredient prior to use? Therefore, as production companies across the US develop storage


facilities for incoming products, a new way of thinking is taking shape, one that is based on “feed quarantine” that brings together information across several fronts including feed science, microbiology and oceanic transport logistics to understand how to minimize risk. This approach is intriguing as it is non-regulatory in nature and does not negatively impact trade.


Conclusions and Next Steps In summary, there is a growing body of scientific evidence suggesting that contaminated feed and feed ingredients are risk factors for the spread of viral diseases at the domestic and the transboundary levels. This information has stimulated collaborative efforts across North America between livestock and grain commodity groups, governmental agencies, and the veterinary profession in an effort to manage this risk. For example, the Canadian Food Inspection Agency has already implemented a national program using designated secondary control zones to manage the introduction of high risk feed ingredients, such as grains, oilseeds and meals from 44 ASFV-positive countries into Canada. While a limited number of Canadian seaports allows for efficient allocation of resources, this is not the case in the US. However, new analytic tools have been developed to track where high-risk imports (soy-based products from China) are entering the US. For example, a recent analysis by Patterson and others indicated that the vast majority (>80%) of soy-based imports entered the US at two of 13 seaports: San Francisco/Oakland, CA (60.4%) and Seattle, WA (20.5%) and this knowledge clearly could enhance the allocation of resources to these


PAGE 60 NOVEMBER/DECEMBER 2019 FEED COMPOUNDER


This article is based on the text of a paper presented by Dr. Scott Dee at the recent Pigs Meeting of the Society of Feed Technologists


specific high-risk sites [18]. In the US, following passage of resolutions from the National


Pork Producers Council requesting collaborative efforts across North America to reduce the risk of foreign animal disease entry via the risk of feed ingredients. The swine industry is rapidly adapting the use of feed additives as chemical mitigants and a Responsible Imports approach as described. In addition, a US feed safety task force involving representatives from governmental agencies, as well as industry stakeholder groups has been formed to develop a national plan to manage this risk. In the near future, representatives from Mexico, Canada and the US will meet to begin the discussion of how to collaborate to reduce the risk of the introduction of ASFV and other foreign animal disease pathogens to North America, with focused discussion on all risk factors including feed. However, there are still differences in opinion as it pertains to feed. While a recent review concluded that the current body of scientific knowledge lacks conclusive evidence of virus contamination of imported non-animal origin feed ingredients of commercial swine feed, [33], another review concluded that there is a moderate risk for the introduction of ASFV and PEDV to the US through contaminated feed [34]. Some reason for this discrepancy is that the latter publication took into account the studies on the transmission of ASFV in feed [19], as well as a recent report citing the detection of Seneca Virus A in swine feed and feed ingredients in Brazil [35], while the former paper did not. Author’s note: My proceedings paper has attempted to build upon the knowledge from the earlier reviews and update the status of the topic with new papers recently published and those pending, as all pertinent publications need to be included before a conclusion can be drawn. However, despite the progress that has been made, significant


research gaps still exist regarding the risk of feed. For example, the vast majority of the published papers are based on experimental inoculation and models. In addition, it is argued that there is a lack of evidence documenting the presence of viral pathogens in actual feed samples around the world. While the current evidence is indeed limited, viable PEDV has been detected in feed bins feeding index cases of PED on sow farms [6] and ASFV DNA has been detected in Chinese feed and feed dust from bulk grains stored on the ground post-harvest, along with samples from feed mills, personnel and delivery vehicles [36]. To compound this problem, a universally validated method to test feed is not available and routine testing of feed and feed ingredients is not permitted in the US. In addition, more information on risk management, i.e. mitigation strategies, is needed. Fortunately, research efforts along these lines are ongoing and will be shared [37]. In closing, it is hoped that these efforts will continue to stimulate


communication and collaboration between the feed and livestock industries, resulting in further research into the emerging concept of “global feed biosecurity”. Ideally, current and future information regarding the risk of pathogen spread in feed will enhance the accuracy of risk assessments, drive the continual development of efficacious feed-based mitigation strategies and ultimately change the philosophy regarding the global trade of feed ingredients from one that based on price to one where


country of origin health status is a major consideration. References available at www.feedcompounder.com/deerefs.htm


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