feed pw2017

1. 42 POULTRY WORLD No. 1, 2017
PHOTO:HENKRISWICK
Safer Salmonella control
in poultry feed
N U T R I T I O N
Salmonella in feed is one of the key causes of colonisation in poultry.
Enterobacteriaceae such as Salmonella can be present in the entire feed
production process, from the raw materials all the way through to the final feed.
Salmonella may then be passed on to consumers. Because of this, feed millers
and integrators aiming to ensure high feed quality standards, need to
demonstrate they have an effective Salmonella control programme.
By Danielle Smeitink, Trouw Nutrition
C
ontrolling Salmonella at the beginning of the
chain, in raw materials and feed, reduces preva-
lence from the very start. The practical example
in this article shows how a Salmonella audit can
support feed millers to take the most appropri-
ate steps. It also demonstrates how a strict control pro-
gramme, involving a combination of feed additives, regular
expert checks and interventions, leads to effective results
without any need for aggressive treatments such as the use
of formaldehyde.
A Salmonella audit
throughout the feed
chain can support
feed millers to take
the most appropriate
steps to reduce the
bugs prevalence.
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2. 43POULTRY WORLD No. 1, 2017
5
4.5
CFU/g(log)
4
3.5
3
2.5
Form
aldehyde
Fysal0%
Fysal0.5%
Fysal0.75%
Fysal1.0%
2
1.5
t=2 t=4 t=7 target
Figure 1 - Enterobacteriaceae count (log CFU/g) per
treatment. Fysal 0% is untreated and Fysal 0.5%, 0.75%
and 1.0% indicate inclusion level of Selko Fysal. t: time
in days.
Raw materials
7
3
4
6
5
2
1
Fysal®
liquid
Fysal®
Feed
Processing
Feed production
Figure 2 - Schematic representation of the production line. The stars indicate
high levels of Enterobacteriaceae. The arrows show the points at which Selko
Fysal feed additives are introduced. Raw material intake (1), inside the grinder
(2), bunker pre-mixer (3), cleaning sieve (4), loading sieve (5), end product (6),
and vacuum cleaner (7).
Mixer
Cooling
Pelletizer
A safe solution for high-calcium feeds
A Dutch feed miller was looking into alternatives to formal-
dehyde in order to control Enterobacteriaceae in its feed for
layers (including eggs for vaccine production) and breeders.
These types of feed are not pelletised and contain a relatively
large amount of calcium. The combination of these character-
istics makes it difficult to decontaminate the feed effectively.
A high calcium level neutralises many acids used and without
pelletising the feed is not heated, both of which prevent
decontamination. This was why the feed miller employed for-
maldehyde, which is an aggressive decontamination product.
As there are safety concerns with the use of this product, this
feed miller wanted to try using a gentler method based on
organic acids. The feed mill had set the quality standard at a
level of less than 10³
cfu Enterobacteriaceae per gram of feed.
In addition, they wished to have an automatic dosing system
to add the feed additives to the feed.
Initial assessment
Firstly, feed samples were taken for a dose-response study in
order to find the optimum dosage level to reach the quality
goal in the most economical way. The baseline results showed
that the Enterobacteriaceae level was very high in both the
untreated and the formaldehyde-treated samples. Only a very
high dosage of the organic acids could reduce this to the
desired level (Figure 1). A decision was taken to investigate the
production system more thoroughly to solve the problem.
A full Salmonella audit was performed in the entire production
system. Samples were taken in several places, as indicated by
the numbers in Figure 2, including from spots where dust nor-
mally collects, like sieves. Scrapings from the inside of
machines were also taken, since these locations are at risk of
Enterobacteriaceae contamination. Finally, samples of the raw
materials were taken to measure their microbial quality, both
before and after grinding. The results revealed that the inside
of the grinder was high in Enterobacteriaceae, with levels of up
to 24,000 cfu/g. However, the ground wheat used for the feed
had even higher levels, up to 110,000 cfu/g. These findings
showed that the high Enterobacteriaceae level in the feed was
mainly due to the contamination of the wheat after grinding.
Integrated approach
Based on these findings, a new plan to manage the
Enterobacteriaceae level was proposed. Since there were
­multiple sources of contamination, an integrated approach
was applied in which feed additives with specific modes of
action were used to treat specific areas. As shown in figure 2,
the raw material, left-overs in the system and the final feed
were treated.
The complete feed safety programme used to prevent the
high Enterobacteriaceae counts for this feed mill included;
Adding a feed additive (Selko Fysal liquid) based on organic
acids to high-risk raw materials (whole grains) at 0.4%
­inclusion, spraying the grinder once a week with another
feed additive (Selko Fysal SP) using a powder duster, in
order to reduce the bacterial level in the feed left-overs and
adding a third feed additive (Selko Fysal Feed) to the feed in
the mixer at 0.5% inclusion rate, to prevent later contamina-
tion with Enterobacteriaceae.
The high level of active ingredients in the used additives
assured efficacy despite of the high buffer capacity of the
feed, giving the organic acids combination in the formula
the chance to reduce the level of Enterobacteriaceae. This
combined solution proved to be more cost-effective due to
the lower inclusion rate necessary and this still helped the
feed miller to reach the goal of less than 103 CFU Entero­
bacteriaceae without the use of formaldehyde.
The key to such a successful and safe Enterobacteriaceae
(including Salmonella) control programme involves finding
out where the risks are located and having the expertise and
correct equipment to apply the most effective products in the
right places. The best results can be achieved when dosage
advice is based on studies with the raw materials used on site,
because bacterial load and raw material conditions differ
from place to place. By testing the effects of several different
dosage levels, it is possible to define the most economical
dosage for optimal results.
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