Ventilation Shutdown: who takes the responsibility to flip the switch?

AVT Applied Veterinary Technologies Europe AB
Address details: c/o INTRED, Södra Hamnen 2, 45142 Uddevalla, Sweden
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E-mail: harm.kie@gmail.com LinkedIn Group: AVT
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Neutralizing risks instead of Stamping-Out
Pre publishing version

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Summary
On September 18, 2015 the USA Government and the American egg producers
announced that they would accept the Ventilation shutdown method as a method of
mass destruction of poultry when other options, notably water-based foam and CO2, are
not available for culling at the farm within 24-36 hours. This is actually the case on all
caged layer farms in the USA, in particular in Iowa.
The Ventilation shutdown method consists of stopping ventilation, cutting off drinking
water supply, and turning on heaters to raise the temperature in the poultry house to a
level between 38 Celsius and 50 Celsius. Birds die of heat stress and by lack of oxygen in
a process that easily takes over after a period of at least 3 days. Ventilation shutdown is
a killing method without prior stunning of the birds, and as such is contrary to all
international Animal Welfare standards.
Animal welfare specialists in disease control strongly oppose this introduction of the
cruelest method of killing poultry that lost their economic value. The Humane Society
(HSUS) described it as the “inhumane mass baking of live chickens”. With adequate
preparation the alternative methods, like the water-based Anoxia foam method, can be
available at each farm for immediate use in case of an outbreak. The ban of the
Ventilation shutdown method should therefore be maintained and the Anoxia method
should be further developed so that is suitable for application to caged layers and
turkeys. In Germany, such a systemis currently under development and will become
commercially available soon.
The poultry industry in the USA ignores this development and asks for a formal approval
of the Ventilation Shutdown method. Speaking on August 19, 2015, during the United
Egg Producers (UEP) national briefing webinar, UEP President Chad Gregory explained
that much research is being done concerning the feasibility of such a depopulation
program.
“The government, the producers, the states and UEP, we all recognize that
depopulation is going to have to happen faster and ideally within 24 hours.”
Quick depopulation of affected flocks is important, Gregory said, because the sooner a
flock is depopulated, the risk of the virus going into fans and out into the atmosphere
becomes smaller. Gregory said ventilation shutdown – if approved – would probably
only be used in a worst-case scenario or when all other euthanasia options have been
exhausted. Gregory did not elaborate on how to adequately prevent outbreaks and how
to promote more animal-friendly methods.

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The latest draft of the USDA Foreign Animal Disease Preparation Plan was published on
August 25, 2015, and the publication of the Ventilation Shutdown Evidence & Policy on
September 18, 2015, effectively created facts on the ground. This was done in a
unilateral way, without any political consultation, without informing trade partners, and
without a fundamental discussion whether or not the Ventilation Shutdown method
should be made acceptable at all.
From a strategic point of view, the US poultry industry created an unprecedented
commercial advantage for itself. Their competitors in Europe are responsible for
biosecurity and for prevention of risks of infection, based on EU legislation. Each country
has to implement a National Emergency Response plan based on Directive EC
1099/2009.
In Germany, public private partnerships called “Tierseuchenkasse” are responsible for
the preparation of emergency response to outbreaks like HPAI, and work on an
insurance model. The German government, the EU and the industry collectively carry
the costs for emergency response activities.
This is not the case in the USA. There, USDA APHIS is responsible for response activities
and the taxpayer is paying the costs. This is a significant advantage over European
producers, and with the TTIP 'free trade' negotiations in their final stage, the European
poultry industry will be confronted with a significant distortion of trading conditions by
this abandonment of animal welfare as a boundary condition in culling operations in the
USA.
US egg producers are actively creating facts that will be very difficult to undo, and with
the Ventilation Shutdown Method officially accepted by USDA Aphis, the industry
effectively avoids to take its responsibility for risks inherent to the type of production
with 31.000.000 caged layers, packed on 35 farms, and caged layer farms with an
average size of 913.000 caged layers per farm. The consequences will be devastating: all
Asian producers, who routinely use cage systems to produce eggs, will follow the
example of the USA, just to be able to compete with the American poultry industry.
For the producers within the EU, it will even more difficult to compete with the US
poultry producers. The ventilation shutdown method will on the mid- and long term
destroy cage free egg production policy in Europe, putting the EU egg production
methods as demanded by the European consumers at risk. In case the European
industry would not able to produce against compatible prices, the consumers will
become completely dependent on eggs produced outside the EU. As the situation is

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now, TTIP will not allow for mandatory labeling of animal welfare on eggs, so that EU
consumers only will have the price as their decision criterion.
Conclusion
Senator Ron Johnson calls emergency response an economic issue; the Foreign Animal
Disease Preparedness & Response Plan puts the limit for Stamping-Out on 24 hours;
official guidelines introduce the Ventilation Shutdown method as a legitimate culling
method in situations described as “where all other euthanasia options have been
exhausted’ - the Ventilation Shutdown method in the USA is a fact with disastrous
consequences for animal welfare and a new obstacle to TTIP.
Harm Kiezebrink
AssociateResearch Fellow
Principal consultantApplied Veterinary Technologies

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SUMMARY 2
INTRODUCTION OF AVIAN INFLUENZA INTO THE INDUSTRY 6
DIFFERENT DRIVERS 7
TRANSMISSION ROUTES 8
CATEGORY 1: INTRODUCTION OF THE INFECTION INTO THE FARM 8
CATEGORY 2: ONWARD-SPREAD BETWEEN FARMS 9
A) TRANSMISSION THROUGH CONTACT STRUCTURE BETWEEN FARMS 9
B) WIND-MEDIATED SPREAD 10
C) RODENTS, SCAVENGERS AND FARM DOGS 10
CATEGORY 3: SPREADING DURING OUTBREAKS 10
TRANSMISSION RISKS WITHIN THE POULTRY INDUSTRY 12
SPECIFIC RISKS RELATED TO LAYER- AND TURKEY FARMS 12
ACUTE SHORTAGE OF RESPONDERS AND CRIMINAL OPPORTUNITIES 13
CARCASS DISPOSAL 15
WHO DARES TO FLICK THE SWITCH? 16
FOREIGN ANIMAL DISEASE PREPAREDNESS & RESPONSE PLAN 17
DEPOPULATION WITHIN 24 HOURS 18
NATIONAL ANIMAL HEALTH EMERGENCY MANAGEMENT SYSTEM NAHEMS 18
$30 PER BIRD 20
STAMP IT OUT! 21
RISK CALCULATION 22
CALCULATION NUMBER OF RUNNERS 22
CALCULATION CATCHERS 23
REFERENCES 25

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Introduction of Avian Influenza into the industry
There are several factors, which contribute to the unique presentation of an avian
influenza outbreak, like the relationship of this virus with wild waterfowl. The virus is
highly pathogenic for chickens and turkeys but not pathogenic for waterfowl.
Since the virus in our current outbreak is not pathogenic for waterfowl, the vast flocks of
healthy virus-infected migratory geese and ducks travel thousands of miles, entering
into commercial poultry-producing regions while shedding tremendous quantities of
infectious avian influenza virus in their feces.
In a recently published studyi (in Dutch) by the
University of Wageningen, wild ducks were identified
as a high risk factor for the introduction of Low
Pathogen Avian Influenza viruses in free-range laying
hens.
It seems logical that the regular presence of wild
ducks in the free-range increases the risk exposure of
the chickens LPAI virus since wild waterfowl are the
natural reservoir of avian influenza viruses.
Another study, published in 2009 ii describes that the
spatio-temporal dynamics of global H5N1 outbreaks match
bird migration patterns. The potential mechanisms
explaining the spread of the H5N1 virus, and the role of
wild birds, were analyzed, demonstrating that between
December 2003 and December 2006, three global
epidemic phases of H5N1 influenza were identified.
These H5N1 outbreaks showed a clear seasonal pattern,
with a high density of outbreaks in winter and early spring
(i.e., October to March). In phase I and II only the East Asia Australian flyway was
affected. During phase III, the H5N1 viruses started to appear in four other flyways: the
Central Asian flyway, the Black Sea Mediterranean flyway, the East Atlantic flyway and
the East Africa West Asian flyway.

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A third study iii that is worth mentioning is
revealed two different transmission modes
of H5N1 viruses in China, and indicated a
significant role of poultry in virus
dissemination. Furthermore, selective
pressure posed by vaccination was found in
virus evolution in the country. In some
geographic regions has had an enormous
impact on the poultry industry and presents
a serious threat to human health.
Different drivers
The association with migratory flyways has also been found in the intra-continental
spread of the low pathogenic avian influenza virus in North American wild birds. These
different environmental drivers suggest that different spread mechanisms operate.
Avian Influenza might spread to poultry via both poultry and wild birds, iv through direct
(via other birds) or indirect (e.g. via
contaminated environment) infection.
Outbreaks in wild birds are mainly caused by
transmission via wild birds alone, through
sharing foraging areas or shelters. These
findings are in contrast with previous
studies, which did not find environmental
differences between disease outbreaks in
poultry and wild birds in Europe.

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Transmission routes
The routes of virus transmission risks can be split into three categories:
1. Introduction of the infection into the farm
2. Onward-spread between farms
3. Spreading during outbreaks
Introduction into the farm entails the target farm’s exposure through incoming contacts
(human and fomite), through inputs such as feed and egg trays and through
neighborhood-related risks such as air-borne contamination. Onward spreading and
spreading during outbreaks can be through farm outputs (waste and non-waste),
outgoing contacts (human and fomite) and contamination of the neighborhood (e.g.,
through emissions from the farm). Therefore, all day-to-day farm activities involving
people and/or materials and/or equipment going in or out of the farm must be
systematically analyzed.
Category 1: Introduction of the infection into the farm
During the last HPAI H5N8 epidemic in the Netherlands (2014), a total of 5 traditional
poultry became infected by separate introductions, from outside the building to inside
and in contact with the birds. The risk of
introducing the virus to a farm can be
determined from the farm’s
neighborhood characteristics, its contact
structure and its biosecurity practicesv.
Neighborhood characteristics include
factors such as the presence of water
bodies (accessed by wild birds), the
density of poultry farms (together with
the number and type of birds on these
farms) and poultry-related businesses
and the road network. The use of manure in the farm’s vicinity is also deemed to be
risky.
In nature, disease-causing strains of avian influenza rarely spread far because the birds
sicken and die before they can fly to spread it to others. However, in unnatural,
intensive agricultural systems, pathogens are more easily able to evolve from mild
strains to dangerous, highly pathogenic forms.

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Category 2: Onward-spread between farms
In Iowa, cage layer housing conditions (confining in average more than 100,000 animals
each) may have an effect on immunity, but there is no such thing as being more or less
susceptible to avian influenza virus infection; poultry in outdoor facilities that have more
opportunities to engage in natural behavior are not more resistant to AI infection.
Probably the housing conditions themselves (windowless sheds, intensely overcrowded,
unsanitary, with stressful living conditions for the birds) make exposure to AI virus
easier. In the Netherlands it has been shown that. Layer farms with outdoor facilities
and therefore more and better contact with wild water birds have a much higher
probability of introduction of AI virus than traditional indoor layer farms (which do not
have windowless sheds).
Nine out of 10 chickens used for egg production in the U.S. are confined in barren wire
cages. Due to the extreme confinement, hens —highly intelligent and social animals —
cannot engage in natural behaviors. High levels of stress can lead to weakened
immunity, rendering animals much more susceptible to disease. This makes the average
caged layer farm in Iowa a plausible hotbed for outbreaks of avian flu.
Still, it is unlikely that the confinement of hens in cages is the only explanation for the
current outbreaks in the U.S, especially in Iowa. The industrial indoor housing in remote
locations with large distances between farm locations has always been considered as
the perfect protection against introduction of viruses to the farm. Considering the
current pace of outbreaks over large areas, other factors might have caused the
transmission between farms, like:
a) Transmission through contact structure between farms
b) Wind-mediated spread
c) Transmission via rodents and farm dogs
a) Transmission through contact structure between farms
Contacts between people, equipment and vehicles prior and during outbreak situations
are critical to determine the possible source of infection of a farm vi. Hired laborers are
known to play a big role in interconnecting
farms.
The farm’s exposure through incoming contacts
(human and fomite), through inputs such as
feed and egg trays and through neighborhood-
related risks such as air-borne contamination.
The latter can be through farm outputs (waste

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and non-waste), outgoing contacts (human and fomite) and contamination of the
neighborhood (e.g., through water- or airborne emissions from the farm).
b) Wind-mediated spread
In the study, publishedvii in 2012 by Rolf Ypma
et al, a comparison between the transmission
risk pattern predicted by the model and the
pattern observed during the 2003 Netherlands
epidemic reveals that the wind-borne route
alone is insufficient to explain the observations
although it could contribute substantially to the
spread over short distance ranges, for example,
explaining 24% of the transmission over distances up to 25 km.
c) Rodents, scavengers and farm dogs
Besides a study published in 2007viii Taiwan, little research has been undertaken into the
transmission routes via rodents, scavengers and farm dogs. There are strong indicators
for the assumption that rodents, scavengers and farm dogs could play a role in
distributing and reintroducing HPAI.
Recently Avian Influenza was found in a farm dog in
South Korea. The dog had antigens for the highly
pathogenic H5N8.
Since the first case of a dog being infected with the
poultry virus in March 2014, there have been 55 dogs
found with antibodies to the bird flu virus. This is the first
time bird flu has been found in a dog in Korea through
the detection of antigens.
Category 3: Spreading during outbreaks
The impact of the outbreak of the Avian Flu Epidemic outbreak in the Netherlands in
2003 ix shows that biosecurity during outbreaks is one of the main issues to address. An
estimated 1.000 people, possibly more have been shown to carry antibodies to the
H7N7 virus active at that time.
Although the risk of transmission of these viruses to humans was initially thought to be
low, an outbreak investigation was launched to assess the extent of transmission of
influenza A virus subtype H7N7 from chickens to humans.

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Most H7 cases were detected in the cullers. The
attack rate (proportion of persons at risk that
developed symptoms) of conjunctivitis was
highest in veterinarians, and both cullers and
veterinarians had the highest estimated attack
rate of confirmed A/H7N7 infections.
From all people that had been questioned, 453 people had health complaints—349
reported conjunctivitis, 90 had influenza-like illness, and 67 had other complaints. We
detected A/H7 in conjunctival samples from 78 (26·4%) people with conjunctivitis only,
in five (9·4%) with influenza-like illness and conjunctivitis, in two (5·4%) with influenza-
like illness only, and in four (6%) who reported other symptoms. Most positive samples
had been collected within 5 days of symptom onset.
A/H7 infection was confirmed in three contacts (of 83 tested), one of whom developed
influenza-like illness. In three of these exposed contacts an A/H7N7 infection was
confirmed. All three were household contacts. The first contact was the 13-year-old
daughter of a poultry worker, who developed conjunctivitis approximately 10 days after
onset of symptoms in her father. Six people had influenza A/H3N2 infection.

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Transmission risks within the poultry industry
Before introduction of the ban on conventional battery cages in the EU from January
2012, battery cages were still common in the Netherlands. An evaluation of the
statistics of the Dutch outbreak (in total 1.134 culling operations - more than 29 million
birds) shows that 79.2% of all the infected/suspected farms H7N7 was reintroduced
were labor-intensive layers/parent stock farms; 8,7 % were turkey farms.
Compared to the production of broilers, the layer industry is much more labor intensive.
Specialized agricultural service providers are contracted to supply the workforce for
tasks like egg collection, depopulation, cleaning & disinfection, vaccination etc. The
same service providers are contracted to supply the workforce to depopulate the farms
during outbreak situations.
Because this labor force contains of staff that is partly contracted on short-term basis
(for instance seasonal workers), it is almost impossible keep track of where the staff is
coming from or where it will be working in the future. Even when all farm workers are
officially registered, it is very difficult to guarantee that the workforce in teams that only
carry out normal farm work and teams that strictly work as responders on infected
farms. This makes the layer- and turkey industry vulnerable for labor related risks of
transmission. It was possibly one of the main reasons why the outbreak in Holland in
2003 was so difficult to control.
Specific risks related to layer- and turkey farms
Managing simple response tasks might look simple, but these get extremely
complicated: most responders are untrained and insufficiently prepared to carry out
79.2%
12.0%
8.7%
Type of farms infected during the H7N7 outbreak in Holland
Labor-intensive farms (Layers/parent
stock)
Labor-extensive farms
(broiler/breeders)
Turkey farms

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heavy labor in narrow houses, under stressful circumstances, and wearing
uncomfortable protective clothing. Breaches of biosecurity during outbreaks are
belonging therefore to the most likely routes of transmission.
The veterinary authorities in Iowa and Minnesota face huge managerial and logistical
challenges when faced with depopulation and biosecurity protection on the highest
level at the same time. The labor intensity of response activities – and the number of
people needed to depopulate layer farms with an average size per farm of almost 1
million layers (compared to an average 21,500 layers on Dutch layer farms) and -in
average- 51,800 turkeys per farm (compared to 13,250 turkeys on Dutch turkey farms).
The enormous size of farms will make it almost impossible to prevent transmission
outside the infected areas.
The size of the U.S. farms is one of the most complicating factors to bring the outbreak
under control.
Similar to the situation of the Dutch outbreak specialized poultry workers are used
simultaneously as responders during outbreak situations. And because of that, farm
activities on non-infected farms and response activities on suspected/infected farms
need to be strictly separated. This in itself causes massive pressure on the veterinary
authorities to deploy sufficient responders. For that reason, responders are brought in
from different parts of the country, opening up the transmission routes to uninfected
areas and causing introduction of viruses into uninfected areas.
Acute shortage of responders and criminal opportunities
A study published in The Lancet (2004)x noted an unexpectedly high number of
transmissions of avian influenza A virus subtype H7N7 in people directly involved in
handling infected poultry during the 2003 outbreak in the Netherlands. This provides
evidence for person-to-person transmission pathways.
23%
68%
9%
Infected farm type
Chickens
Turkeys
Mixed
poultry
85%
15%
Infected poultry species
Chickens
Turkeys

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Although in 2003 the Dutch veterinary authority RVV did not expect that the risk of
infection of responders turned out to be 50%, it created a directive to minimize the risks
that the virus would transmit through farm workers and responders. The RVV ruled that
it was strictly forbidden for farm workers and responders who had been active on
infected farms to visit and/or work on non-infected farms within a time frame of 72
hours. Contractors were obliged to keep a strict record of where their staff has been
working.
This measure complicated the task of finding enough staff to carry out response
activities. RVV took a bold step and decided to deploy asylum seekers through a
specialized agricultural service in the south of the Netherlands provider because of the
urgency and the acute shortage of staff. All these hundreds of asylum seekers were
subject to a fake registration under the same name (F. Vogelpest, birdflu in Dutch), born
on April 14, 2003, unmarried, and all with the same social security number 2494 88 039.
This unfortunate step of RVV made it almost impossible to reconstruct the transmission
route through this group of responders.
These emergency responders were normaly deployed as
seasonal laborers to harvest asparagus. With the support of
a local tax officer, these untrained laborers were deployed in
the area of the first outbreak in the center of the
Netherlands to collect dead chickens after stable gassing.
One month later, a second wave of outbreaks took place in
the direct proximity of this service provider in the south, in
an area with mainly layer farms that used the services of this
service provider.
It is difficult to determine where his fraudulent activities
started and stopped, so it is also difficult to find out what the role his staff – including
the staff he normally deployed in the poultry industry in the southern part of the
Netherlands – actually was in terms of transmission from the area around Barneveld to
the farms in the southern part of the Netherlands and Belgium (April 16, 2003
Meeuwen-Gruitrode).
The owner of the service provider was arrested in 2003, and in June 2007, he was
convicted for tempering with the registration of responders that were deployed during
the outbreak. This story has been well documented in the Dutch pressxi, but never been
published internationally.

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Carcass disposal
A similar situation is occurring within the U.S. poultry industry at this moment, but even
on a larger scale, due to the farming infrastructure and the staggering numbers of birds
that are culled - more than 46 million/170 million tons of carcasses - and need to be
disposed of. In an article published in Des Moines Gazettexii Tom Vilsack, the U.S.
secretary of agriculture recently stated that the federal government is addressing the
outbreak by attempting to be thorough, safe and expedient, but that process was
slowed by a lack of locations to dispose of the destroyed birds.
The outbreak in the U.S. is unprecedented in the history of poultry farming. All infected
birds need to be handled at the farm, transported to the disposal location and than
buried or incinerated. Vilsack pointed out that the disposal process has been holding up
the process of stamping out. He said the government has reached agreements with a
handful of landfills and incinerators, so he hopes disposal will begin to move more
briskly. He said finding willing partners that are willing to dispose the carcasses was not
easy. Some facilities expressed willingness to take destroyed birds, but backed off after
hearing concerns from neighbors.

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Who dares to flick the switch?
The Ventilation Shut down method is considered the most gruesome way for wholesale
killing of chickens. Still, it is by far the most method economic depopulation. The
principle is simple, all it takes is shut down all doors and windows; place mobile heaters;
and flick the switch of the ventilation system. Without ventilation, air becomes still;
temperatures raise; chickens suffer; their organs eventually fail; they become lethargic;
and they eventually die of either heat stress, or suffocation, or both. It can take as long
as three hours for the birds to die. Ventilation shut down is killing poultry without prior
stunning, and thus violates all International Animal Welfare standards.
Stamping out strategy
The United States’ primary control and eradication strategy for HPAI in domestic
poultry, also known as the “Stamping Out Strategy”, is based on the recommendations
of the OIE (World Organization for Animal Health). In particular, rapid depopulation of
infected poultry is considered as critical to halt virus transmission. In the OIE terrestrial
code, stamping out is defined as:
1. The killing of animals, which are affected, and those suspected of being affected
in the herd and, where appropriate, those in other herds which have been
exposed to infection by direct animal to animal contact, or by indirect contact
with the causal pathogen; this includes all susceptible animals, vaccinated or
unvaccinated, on infected establishments; animals should be killed.
2. The destruction of their carcasses by rendering, burning or burial, or by any
other method
3. The cleansing and disinfection of establishments through procedures
In the latest draft of the Red Book - Foreign Animal Disease Preparedness & Response
Planxiii - published in August 2015, the goal for the depopulation activities is described as
“within 24 hours”, without reference to the scientific basis, if any, of this timeframe.
Without sufficient well-trained workers; equipment; gas/water/electricity; cleaning &
disinfection capacity; carcass disposal facilities, etc., it is impossible to carry out the
Stamping-Out strategy. This is particularly the case on farms of over 100.000 caged
birds, unless there are unlimited resources available.
This was not the case in Iowa, where the latest outbreak of H5N2 destroyed the entire
layer industry. The average size of an Iowa layer farm is 913.000 caged birds. John
Clifford, the Chief Veterinary Officer for the U.S. Department of Agriculture, explained

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the true reason for introducing the ventilation shutdown method during the Homeland
Security hearing held on July 7 2015:
The problem with these methods, Clifford explained during the hearingxivxv, is that a
farmer can use them to kill only so many chickens at once.
"You can only take out about 100,000-plus birds a day out of one house and C02
those," he said, when there are farms with millions of birds that have to be
euthanized." We need to allow all tools to be used in the toolbox," Clifford said.
"Any delay in putting birds down puts more virus into the environment."
Ventilation shutdown, he reminded, can be used to kill as many birds as fit in a
single barn.
In his opening statement of a hearing session in the US senate, chairman Senator Ron
Johnson stated that the management of future outbreaks is purely an economic issue. In
the past H5N2 outbreak, 40 million caged layers (13,2% of the entire 300 million US
layer production) were wiped out, causing a damage 8 billion dollars; 32 million layers
(80% of total infected layers) were located in Iowa. It is obvious that Iowa is not able to
handle a second wave of H5N2, and therefore drastic measures are now being
effectuated.
Foreign Animal Disease Preparedness & Response Plan
In an attempt to legitimize their actions, USA APHIS refers to the OIE and the UK. In the
introduction of the draft of the Foreign Animal Disease Preparedness & Response Planxvi
also known as ‘The 'Red Book’, published in August 2015, is mentioned in the first page:
“The changes in the latest version [of the Foreign Animal Disease Preparedness
& Response Plan] Reflects the 2015 OIE Terrestrial Animal Health Code.”
Further on in the introduction, the OIE is referred to for the second time:
“The United States’ primary control and eradication strategy for HPAI in domestic
poultry, as recommended by the World Organization for Animal Health (OIE), is
“stamping - out.”
Implementing policies on the basis of the Terrestrial Code implies the all activities are in
accordance with the OIE, especially when it comes to issues like animal welfare,
vaccination and International trade. In more detail, the HPAI Response Plan includes
what is defined in Chapter 7 of the Terrestrial Code:
“Animal welfare means how an animal is coping with the conditions in which it
lives. An animal is in a good state of welfare if (as indicated by scientific

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evidence) it is healthy, comfortable, well nourished, safe, able to express innate
behavior, and if it is not suffering from unpleasant states such as pain, fear, and
distress.”
Depopulation within 24 hours
Speaking August 19 2015,during the United Egg Producers (UEP) national briefing
webinar, UEP President Chad Gregory asked for allowing the ventilation shutdown
method as a measure of last resort, arguing that such a quick depopulation of affected
flocks is important. The sooner a flock is removed; the risk of the virus going into fans
and out into the atmosphere becomes smaller.
“The government, the producers, the states and UEP, we all recognize that
depopulation is going to have to happen faster and ideally within 24 hours.”
The Red Book states (in chapter 4.3.1) as the first critical goal of the OIE based Stamping
Out Strategy:
“The goal [of the Stamping Out strategy] is that, within 24 hours of (or as soon as
possible after) a presumptive positive classification, infected poultry are
depopulated in the quickest, safest, and most humane way possible.”
By referring to the OIE terminology for Stamping out, the Red Book suggests that the 24-
hour timeframe is following the demand of the OIE, However, the OIE Terrestrial Code
does not mention a specific period within all animals need to be culled. It only describes
a period of 24-48 hours to trace all susceptible animals, so to include active surveillance
as part of the emergency response planning.
This is therefore an important point, because further on in the Red Book it becomes
clear what on the basis of the new plan might apply. In Chapter 5.13.1 Depopulation
Goal & Methods are very briefly described:
“Carbon dioxide and water-based foam concentrate have most commonly been
used to depopulate poultry flocks. However, to meet the goal of depopulation
within 24 hours and halt virus production, other alternative methods may also be
considered by State and APHIS officials.”
National Animal Health Emergency Management System
NAHEMS
Further on the Red Book refers to the National Animal Health Emergency Management
System NAHEMS guidelines for mass depopulation and euthanasiaxvii. These guidelines
describe in details how mass population is implemented in case of an outbreak. Under

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chapter 14.8, it becomes finally clear what the true intentions of all the changes are: the
introduction of the Ventilation Shutdown method:
“Ventilation shutdown is defined as the cessation of natural or mechanical
ventilation of atmospheric air in a building where birds are housed, with or
without action to increase the ambient temperature. Although this method has
not yet been addressed by the AVMA, it is approved in the United Kingdom as a
killing method for poultry in certain disease control situations.”
Ventilation shutdown is not part of the EU legislation and is only allowed under UK
lawxviii under the condition that all other depopulation methods failed:
“Authority to use Ventilation Shutdown (VSD) will not be given unless Highly
Pathogenic Avian Influenza (HPAI) infection has been confirmed. VSD can only be
used as a last resort. All other permitted killing methods must be explored and
discounted first.”

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20
$30 per bird
According to the Red Book, the goal is set to stamp-out the disease within a timeframe
of 24 hours. Let’s take the situation for the layer industry in Iowa – the largest egg-
producing state in the USA — earlier this year. According to the hearing in the US
Senatexix and UDSA APHISxx, the facts are astonishing:
 The outbreak was under control within a timeframe of 8 weeks (starting on April
20, 2015/ ending on June 17, 2015)
 In total, 33.1 million birds were killed, of which 32 million were caged layers
 In total 71 farms were infected, of witch 35 caged layer farms
 The average layer farm size is 913.000 layers
 Per layer farm, in average 1.188 tons of carcasses (average weight 1,3 kg/layer)
were disposed
 In total 51.700 tons of carcasses were disposed, of witch 41.565 tons layer hens
 The total costs of the outbreak in the USA are estimated on 8 billion USD, of
witch 1 billion USD for Iowa; an astonishing $30 per bird
 The bird owner is being compensated; the contractors don’t get any form of
compensation for their losses
 A study, conducted by the Iowa Farm Bureau Federationxxi, shows that the AI
outbreak is cost Iowa nearly 8,500 jobs
 In addition to job losses, the AI outbreak will cost Iowa nearly $427 million in lost
additional value, more than half of which is income for Iowans.
The only conclusion is that the US poultry industry was absolutely not prepared for a
large-scale outbreak, despite all their methodical planning efforts and detailed
emergency response plans. In fact, they didn’t even have qualified methods available for
culling and disposal at the time of the outbreak.
During the senates Homeland Security hearing, USA’s Chief Veterinary Officer admitted
that USDA has only a staff of 1.800 qualified animal health technicians and veterinary
medical officers that are trained to manage outbreak situations. For a country with one
of the largest poultry populations in the word, this is absolutely insufficient to handle
and manage large-scale outbreak situations.

Org.nr: 556792-1944 - Phone: +46 761 731 779
21
Stamp it out!
According to the definition of stamping-out, the following issues need to be addressed
within this timeframe:
1. Killing of all animals on the farm
2. Destruction of all carcasses
3. Cleansing and disinfection of all establishments
The speed of the stamping-out is depending on several factors that need to be taken
into account, like:
 Size of the farm
 Number of sheds
 Type of housing
 Type of animal species
 Size of the animals
 Number of animals
 Type of disposal
 Availability of sufficient - well-trained – responders
 Disposal of animals once euthanized
 The availability of sufficient disposal capacity
 Availability of sufficient logistic materials, trucks, containers, cleaning &
disinfection, etc.
 Environment where animals are maintained (e.g., pasture, feedlot, dairy barn,
swamp)
 Need for specialized equipment (e.g., firearm, gas chamber, chemicals)
 Public acceptance of depopulation or euthanasia method
 Risk of spreading the disease agent via euthanasia/ depopulation procedure
 Human safety
 Hazard to the environment
 Weather and environmental conditions
 Sample contamination on workers who have been in contact with infected
animals and materials as a result of the euthanasia method
Although each farm is different, most of these issues can be registered and addressed
upfront, as part of the Farms Bio Security Plan. In case such farm bio security plans exist
at the moment of an outbreak, managing an outbreak is much more effective/efficient
than when all these issues need to be address under the pressure of an outbreak.

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22
Risk calculation
In the USDA Foreign Animal Disease Preparedness & Response Planxxii published on
August 2015, the proposed method for eradicating large numbers of caged birds is
taking the birds out of their cages; bring them outside the house; place them in a large
roll-off dumpsters (1,400 ft3/40m3, covered with plastic or tarpaulins); filled with >70%
CO2.
The (simplified) steps of the Standard Operating Procedure for culling caged birds is as
follows:
1) Offload a roll-off dumpster and place it on 10 meters from the entrance of the
chicken house
2) Fill the dumpster with 980 ft3/28m3CO2 (70% by volume)
3) When the container is filled with CO2, start the removal process
a. Removal of the chickens out of the cage by a catcher (worker who takes
the birds out of the cage); 6 chickens per/time
b. Hand over 6 chickens to a runner (worker who transports the chickens in
the poultry house to the dumpster)
c. The runner transports the chickens to the dumpster and enters them into
the CO2
d. The runner walks back to the catcher to remove the next 6 birds
4) This process is repeated until the dumpster is filled with 28 tons of carcasses
5) The full dumpster is replaced by the next container that is prepared, containing
980 ft3/28m3CO2
6) The culling procedure stops when all birds are culled.
Calculation number of runners
This procedure needs to be carried out within 24 hours. To calculate the manpower
needed to depopulate a poultry house with 80.000 caged birds, you need the
dimensions and the layout. For this example, I use the layout of an average Big
Dutchman house with 80,000 caged layers:
 Length: 108-meter outside/ 88-meter inside
 Width: 13,3-meter outside/13 meter inside
 Height: 6-meter
 10 rows of cages/8 tiers of cages per row/10.000 layers per row

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23
The average distance a runner has to walk to transport 6 layers to the dumpster is
calculated as follows:
((Average distance from each case = 108m/2) + (distance from the door to the
dumpster = 10m)) x 2 = 128 meters.
The total running time to bring all birds to the container is calculated as follows:
80,000 birds/ 6 birds per run = 13.333 runs
The total distance that needs to be walked by all runners; 128m x 13.333 = 1.706,6 km
A runner walks with an average speed (without rests) of 1 m/s (3,6 km/hour); one
runner could run theoretically 86,4 km/24 hours. This is impossible. Even in case a
worker would only be allowed to work continuously in 4 hours per shift, this would
mean that within this theoretical 4 hours shift (2 shifts/24 hours):
 One walker would walk 14,4 km (1 m/s x 60sec x 60min x 4hours), of which 50%
with chickens in his hands)
 One walker would transport 675 chickens to the dumpster (1m/sec; 60s per
minute x 60 min x 4 hours = 3.600m; with an average of 128m per run; and 6
chickens per run)
 One walker would lift 877,5 kg live birds manually (average weight of 1,3kg per
chicken)
In order to come to a realistic calculation, the efficiency factor for field workers is 75%
of the theoretical capacity.
The total human capacity needed to carry out this culling operation within 24 hours is
therefor calculated as follows:
 Each 24-hour cycle contain 6 shifts of 4 hours each
 Per shift, one runner can carry 675 birds x 75% = 506,25 birds to the dumpster;
 During a 24-hour cycle, one runner can operate during 2 shifts
 Per 24-hour cycle needs 3 runners who run 3.036 birds to the dumpster
 80.000 birds need to be transported to the dumpster within 24 hours
 In total 80 runners are needed to depopulate 80.000 caged birds over a period of
24 hour (80.000 birds/30.36 birds) x 3 runners/cycle.
Calculation catchers
Per 24 hours, 80.000 birds need to be taken out of their cages:
 80.000/ 24 hours = 3.333 birds per hour

Org.nr: 556792-1944 - Phone: +46 761 731 779
24
 Each catch takes approx. 30 seconds
 Per hour, one catcher can catch 6 birds/30 sec x 2 x 60 min = 720 birds/hour
 Per hour, 4,6 catchers are needed
 Each 24-hour cycle contain 6 shifts of 4 hours each
 During a 24-hour cycle, one catcher can operate during 2 shifts
 In total 14 catchers are needed to depopulate 80.000 caged birds over a period
of 24 hour.
Total capacity per 80.000 birds, within a period of 24 hours: 80 + 14 = 94 workers.
With an average farm size of 913.000 birds, 11,4 poultry houses per farm need to be
depopulated, demanding a team of 11,4 x 94 workers = a team of 1.000 well-trained and
well-organized catchers and runners. During the 2 months time period, the
depopulation activities on 35 farms actually took place over in total 19 days of 24 hours.
This means that during an active day 35/19 in average 1,85 culling operations were
carried out simultaneously, almost doubling the number of workers needed on such
day.

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25
References
i Risicofactoren voor introductie van laag- pathogeen aviaire influenza virus op
legpluimveebedrijven met vrije uitloop in Nederland, published by Central Veterinary Institute,
(Wageningen UR), March 24, 2015 -CVI Rapport 15/CVI0078 -
Jeanet van der Goot1 , Armin Elbers1 , Ruth Bouwstra1 ,Teun Fabri3 , Maudia van Wijhe- Kiezebrink2 ,
Thea van Niekerk 2
1 Central Veterinary Institute (CVI), Wageningen UR; 2 Wageningen UR, Livestock Research; 3
Gezondheidsdienst voor Dieren (GD)
ii Spatio-temporal dynamics of global H5N1 outbreaks match bird migration patterns, published
in Geospatial Health 4 (1), 2009, pp.65-78
Yali Si1,2,4 , Andrew K. Skidmore1,2 , Tiejun Wang1 , Willem F. de Boer2 , Pravesh Debba3 , Albert G.
Toxopeus1 , Lin Li4 , Herbert H.T. Prins2
1 Department of Natural Resources, International Institute for Geo-information Science and
Earth Observation (ITC), Hengelosestraat 99, P.O. Box 6, 7500AA Enschede, The Netherlands; 2
Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708 PB Wageningen, The
Netherlands; 3 Logistics and Quantitative Methods, Council for Scientific and Industrial Research,
CSIR Built Environment, P.O. Box 395, 0001 Pretoria, South Africa; 4 School of Resources and
Environmental Science, Wuhan University, Luoyu Road 129, 430079 Wuhan, People’s Republic of
China
iii Spatial, temporal and genetic dynamics of highly pathogenic avian influenza A (H5N1) virus in
China, published by Tian et al. Tian et al. BMC Infectious Diseases (2015) 15:54 DOI
10.1186/s12879-015-0770-x
iv Different Environmental Drivers of Highly Pathogenic Avian Influenza H5N1 Outbreaks in
Poultry and Wild Birds, published online on January 7, 2013
Yali Si1 *, Willem F. de Boer2 , Peng Gong1
1 Ministry of Education Key Laboratory for Earth System Modeling, and Center for Earth System
Science, Tsinghua University, Beijing, China; 2 Resource Ecology Group, Wageningen University,
Wageningen, The Netherlands
v Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 5, May 2015 Author affiliation:
Wageningen University and Research Centre, Central Veterinary Institute, Lelystad, the Netherlands
DOI:http://dx.doi.org/10.3201/eid2105.141839
vi Avian inﬂuenza transmission risks: Analysis of biosecurity measures and contact structure in
Dutch poultry farming, published in, Preventive Veterinary Medicine 109 (2013) 106–115
A. Ssematimba a,b,∗, T.J. Hagenaarsa, J.J. de Witc , F. Ruiterkampc , T.H. Fabric , J.A. Stegemand , M.C.M.
de Jongb
a) Department of Epidemiology, Crisis Organization and Diagnostics, Central Veterinary Institute (CVI)
Part of Wageningen University and Research Centre; b) Quantitative Veterinary Epidemiology,
Department of Animal Sciences, Wageningen University; c) Animal Health Service (AHS); d)
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University

Org.nr: 556792-1944 - Phone: +46 761 731 779
26
vii The Journal of Infectious Diseases, 20013/207 (March 1, 2013) Ypma et al
viii Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 5, May 2008
ix RIVM rapport 630940001/2004, published in 2004 by RIVM Institute for Psycho trauma, the
Netherlands
x Transmission of H7H7 avian influenza A virus to human beings during a large outbreak in
commercial poultry farms in the Netherlands, published in the Lancet Volume 363, February 21,
2004
xi http://vorige.nrc.nl/binnenland/article1590983.ece
xii http://thegazette.com/subject/news/business/vilsack-help-for-bird-flu-on-the-way-20150526
xiiihttps://www.aphis.usda.gov/animal_health/emergency_management/downloads/hpai_response_pla
n.pdf
xiv http://www.c-span.org/video/?327001-1/hearing-combating-avian-influenza
xvii http://www.cfsph.iastate.edu/pdf/fad-prep-nahems-guidelines-mass-depopulation-and-euthanasia
xviii http://n2gf.com/?p=1315; www.defra.gov.uk GUIDELINES FOR KILLING POULTRY USING
VENTILATION SHUTDOWN (VSD) September 2009 Version 9.
xix http://www.c-span.org/video/?327001-1/hearing-combating-avian-influenza
xx Update on Avian Influenza Findings Poultry Findings Confirmed by USDA’s National Veterinary
Services Laboratories, last published on June 17, 2015
xxi http://n2gf.com/?p=2515
xxii http://www.cfsph.iastate.edu/pdf/fad-prep-nahems-guidelines-mass-depopulation-and-euthanasia

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