World Grain - December 2022 - 44

FEED OPERATIONS
SAMPLING'S role in
feed mill biosecurity
Method involving 10 probe samples shown to be
highly effective in screening for biological pathogens
by Chad Paulk and Grace Houston
The US Department of Agriculture has deemed feed ingredients
a negligible to moderate risk for the introduction of
African swine fever virus in the United States. In addition,
there has been research to suggest that feed mills can potentially
disseminate endemic diseases, such as pathogens like
Salmonella, porcine epidemic diarrhea virus (PEDV), porcine
deltacoronavirus (PDCoV), or Seneca valley virus (SVV),
throughout swine production systems. Given this information,
there has been a focus on implementing biosecurity practices
for multiple areas within the feed mill and some areas of
emphasis include:
* Ingredient sourcing
* Receiving practices
* Drivers and delivery
* Feed handling
* Human movement
Although biosecurity practices/processes are being implemented
in these areas, there are limited resources for measuring
the effectiveness of
these processes in terms
of feed mill biosecurity
for pathogen control. In
addition, a limitation to
implementing such strategies
is the sampling
methodology utilized to
detect biological pathogens
in feed ingredients
or complete feed and on
surfaces within a feed
mill environment.
Figure 1.
Feed serving as a
fomite for disease has
been a topic of discussion
for
44
veterinarians,
production
companies, and feed mills since it was speculated
that a contaminated batch of feed introduced PEDV into
North America. Ideally, a feed mill could use the same sample
for nutritional quality analysis in addition to testing for the
pathogen of interest. However, a problem with utilizing this
type of sample for biological pathogen identification is that
biological pathogens like mycotoxins, bacteria, and viruses
are heterogeneously distributed in a single load of feed.
This concept of heterogeneous mixture, or sometimes referred
to as " hot spots, " of biological pathogens of interest
in feed is illustrated in Figure 1 (left) of a feed tote with contamination
illustrated as the red circle in the lower left corner.
The purple cylinders on the tote picture illustrate a possible
single pull sample for nutritional analysis visualizing that
sometimes, most likely due to chance, the biological pathogen
contamination is correctly identified from the feed container.
Therefore, when sampling feed for these pathogens of interest,
a methodology similar to the Association of American
Feed Control Officials (AAFCO) has been effective at identifying
PEDV and ASFV in swine feed. This method consists
of taking 10 probe samples of feed and combining them into
a single composite sample and offers a solution to monitor for
biological pathogens if concerned about potential contamination
in feed ingredients or complete feed. Figure 2 (page 46)
demonstrates how probes should be positioned when looking
down at the container, and inserted at varying depths, to account
for the heterogeneous mixture of biological pathogens
of interest.
Environmental samples
Environmental samples offer another solution to proactively
monitor biological pathogens of interest for a feed mill. Environmental
samples can specifically target areas that have high
foot traffic like feed delivery trucks, areas where workers congregate
like the feed mill office or break room, or surfaces that
December 2022 / World Grain / World-Grain.com
Photos courtesy of AAFCO
http://www.World-Grain.com
World Grain - December 2022

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