Feed biosecurity in the pre-manufacturing stage. Understanding and managing disease transmission risk in the pig feed ingredient supply chain

In article 1, we noted how the transmission of disease through contaminated feed ingredients and feed has been well documented. We also reviewed how the likelihood of spreading disease through the feed supply chain depends on the risk that: 1) the feed or feed ingredient will become contaminated with an infectious pathogen and 2) the risk that the pathogen will survive in the ingredient in a sufficient quantity and retain its level of infectivity to complete the disease transmission process.

In the past half century, the supply chain that provides ingredients for pig feed has evolved into a global network. Of course, this is not unique to the pig feed supply chain. Like so many things that we consume in our every day lives, these ingredients can quickly travel around the globe and enter the daily diet of the animals we raise to nourish our world. Subsequently, the pork and pork by-products we produce can also travel back into that same global food economy to be consumed by people and animals almost anywhere that an active trading relationship exists (Image 1).

Considering the potential for disease transmission and the movement of products both locally and globally, what are the potential implications on the biosecurity of our swine herds? Is this risk significant enough to really spend any time worrying about?

This article will focus on describing the pig feed ingredient supply chain and how it may act as a disease transmission pathway. As well, we will discuss some of the prevention strategies that are commonly recommended to mitigate the risk of disease transmission in this segment of the industry.

As a first step in understanding the risks, it is important to categorize feed ingredients in a way that will help us to evaluate the true risk. Pig feed ingredients can be classified in the following way:

1. Ingredients of animal origin (often categorized as products of non-animal and animal origin)
   1. Rendered (e.g. meat meals, blood meals, animal fat products, etc.)
   2. Spray dried (e.g. spray dried blood plasma)
   3. Hydrolyzed proteins (i.e. by-product of the human heparin manufacturing process)
2. Ingredients of non-animal origin
   1. Plant based products
   2. Minerals
   3. Vitamins and Amino Acids
   4. Others feed ingredients (e.g. antimicrobials, flavours, etc)

After understanding the categories of feed ingredients, the next step is to systematically evaluate whether the risk of disease transmission for each ingredient type is low, medium, or high. Researchers from the University of Minnesota and the Kansas State University published a decision-making process for assessing the risk of pathogen transmission in imported feed ingredients which can be applied to any ingredient whether they are moved locally, regionally, nationally, or internationally. This process utilizes a version of the following questions:

1. Does the ingredient meet the relevant food safety legislation governing traceability and good manufacturing practices?
2. Are animals located on or near the site where the ingredient is being manufactured? (Image 2)
3. If animals are present, has there been an outbreak of disease within the past 6 months?
4. If there has been a disease outbreak, was it a reportable disease? (or was it a disease with significant economic implications for pig production?)
5. Does the ingredient manufacturer incorporate a validated pathogen inactivation process in the manufacturing of their product?

One can clearly see that thoroughly evaluating the true risk of each ingredient, especially those that are sourced from a foreign country, could be a complex undertaking. Following the PEDV experience in North America and the rise of African Swine Fever in Europe and Asia, the focus on evaluating individual ingredient risk has risen sharply. Some research has even identified certain ingredients as carrying a significantly higher or lower risk of pathogen contamination and survival.

However, even though certain ingredients have been categorized into risk categories, a major dilemma for researchers looking at the transmission of disease in feed ingredients is the fact that the actual contamination events are likely to be very infrequent and, therefore, very difficult to identify. Also, if feed ingredients or feed become contaminated by a pathogen, it is not likely to be evenly spread throughout the ‘batch’ of the ingredient or final feed and that makes the likelihood of finding it through a random sampling program almost impossible. However even though the frequency of these events is likely to be very low, the impact of the events, when they do happen, can be catastrophic.

So how can a feed manufacturer that is buying ingredients in a global market manage the risks associated with the ingredients they purchase for use in their final product? Research on these concerns are targeting the best way to answer this question. In the meantime, there are several risk mitigation strategies being incorporated into how ingredients are purchased and used. These include the following:

1. Government regulations banning the use of certain ingredients in animal feed (e.g. regulations on the feeding of waste food products);
2. Employing self-imposed limits on the purchase of ingredients based on an independent evaluation of the country of origin and manufacturing process to evaluate risk;
3. Maintaining ingredients at a minimum temperature for a set period of time; and
4. Adding chemical mitigants or other co-ingredients that have been shown to inactivate infectious pathogens (i.e. formaldehyde, medium chain fatty acids).

In the final article of this series, we will focus on the biosecurity of the feed manufacturing and distribution process.