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The new normal in feed biosecurity for North American agriculture

Date posted: January 6, 2021

New research is showing that animal feed can carry major animal disease including African Swine Fever (ASF). Scott Dee, veterinarian and director of applied research for Minnesota-based Pipestone Veterinary Services gave the 2021 Banff Pork Seminar Jan. 5, an update on a rapidly changing world of feed biosecurity in North America.

The concept of animal feed as a previously overlooked risk factor came to light following the introduction of PEDV into U.S. swine herds in May 2013. Feed ingredients and prepared diets were not considered as potential vehicles for pathogen transport and transmission prior to that time, and no standard biosecurity practices were in place even though swine facilities frequently received new products and supplies on a daily or weekly basis.

The link between diet and disease transmission has raised concerns that U.S. herds could become infected with foreign pathogens through contaminated feed and feed ingredients originating from countries with endemic disease and lax sanitation and quality assurance procedures.

Feed can support viruses

Experimental data has already demonstrated that some feed ingredients, particularly soy-based products, can support the viability of at least three significant viral pathogens of swine (i.e., Classical Swine Fever or CSF, ASF, and PRV). ASF survival has been successfully confirmed in a total of nine distinct feed ingredients, including three soy-based products, choline chloride, three pet diets, pork sausage casings, and complete feed exported from China to the U.S.

Two key variables that influence the viability of viruses in feed include the specific virus's phenotypic properties and the feed matrix that is produced by certain feed ingredients and additives. Some matrices are more conducive to survival and can support several different viruses at the same time.

This discovery had added significance in 2018, when ASF was first isolated in Chinese swine herds. As the U.S. imports soy-based products from several ASFV-positive countries, it becomes important to quantify the amount and type of these products entering the U.S. and to identify at what seaports this importation occurs.

Contaminated feed and feed ingredients are now widely recognized as likely vehicles for the transport and transmission of viral pathogens, highlighting the need for improved biosecurity policies and procedures for imported products intended for use in animal diets. In Canada, restrictions are placed on feed ingredients imported from countries known to be positive for ASF virus that are known to enhance the survival of pathogens, predominantly soy-based products. The Canadian Food Inspection Agency has also established secondary control zones around all national seaports where these high-risk ingredients are received. After arrival, products must be stored under controlled environmental conditions for a specified interval to allow adequate time for viral decay prior to distribution to milling facilities.

The situation is complex in terms of challenges, but also presents unique opportunities to advance agricultural biosecurity. Major challenges reflect the vast scope and magnitude of the problem. Even though the risk of pathogen entry through contaminated feed ingredients may be low, the associated consequences related to a lapse would have extremely negative effects on animal agriculture and commerce.

New technologies emerging

The growing complexity of international trade and expanding movement of feed-related products across multiple borders presents constantly changing circumstances that are increasingly difficult to manage and track. However, new and emerging technologies are developing at an equally rapid pace and can often be leveraged to further enhance the management of these new risk factors at the transboundary and domestic levels.

The use of some chemical additives has been shown to have a negative effect on the survival of viral pathogens in products intended for use as animal feed ingredients. A comparison of 15 different additives, which included organic acids, fatty acid blends, formaldehyde-based products, and essential oils, was recently conducted and the resulting data showed that pigs fed diets with an additive had significantly better health and performance following challenges with PEDV, PRRS, and Seneca virus A as compared to cohorts consuming non-mitigated feeds. Similar results were observed in challenges with ASF, suggesting the use of a validated additive may be efficacious in reducing risks associated with viral-contaminated feed ingredients.

Expanding knowledge on the half-lives of viruses found in essential animal feed ingredients has led to science-based protocols in the U.S., which allow these materials to be safely introduced from high-risk countries.

This approach is referred to as "Responsible Imports" and relies on a comprehensive risk assessment process that considers: 1) the absolute necessity of importing the material(s); 2) the availability of alternative ingredients that can be obtained through other sources (i.e., countries free of foreign diseases of concern); 3) prevalence of specific virus(es) regarded as credible threats; 4) access to reliable data that describes the half-lives of these agents in designated ingredients and their substrates; 5) projected transport times of feed substrates, from source to end destination; 6) mitigation methods and strategies that can be implemented to reduce viral load during transit; and 7) optimal storage temperatures and times that will eliminate residual virus from various ingredients after receipt and prior to use.

The relatively new concept of "feed quarantine" is rapidly evolving, as production companies design storage facilities to safely accommodate incoming products and facilitate secure, long-term trade with a wider range of international partners.

In contrast to the rapid industry-based response to the PEDV epidemic, the risk of feed was immediately downplayed by U.S. governmental agencies, resulting in criticism by the Government Accountability Office (GAO). In their report, the GAO found fault with the USDA's lack of response to the outbreaks in 2013 and 2014, and for insufficient actions taken afterward to prevent future outbreaks. In addition, it stated that the government is not fully prepared to track and respond to emerging diseases that could harm animal health, decrease availability of food, and increase food prices.

Unfortunately, despite the growing body of scientific evidence in support of the risk as it pertains to other pathogens, the risk of feed ingredients continues to be ignored, thereby continuing to expose U.S. agriculture to the risk of the introduction of foreign animal diseases via contaminated feed ingredients.

Coordinated effort needed

Currently, all parties continue to work together to reach consensus. Research on feed risk mitigation is ongoing and results are being communicated between all parties. Industry stakeholder groups and federal agencies continue to interact via a national task force, focusing on the risk of foreign animal disease entry through contaminated feed. In the end, it is hoped that these efforts will stimulate communication and collaboration between the feed and livestock industries, and governmental agencies, furthering the emerging concept of "global feed biosecurity".

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