Re: Culling by suffocation



"Malcolm" <Malcolm@xxxxxxxxxxxxxxxxxx> wrote in message
news:LWKXVHG382XEFwyu@xxxxxxxxxxxxxxxxxxxxx

In article <445f634c$0$9251$ed2619ec@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Jill
<news@xxxxxxxxxxxxxxxxxxxxx> writes
"Oz" <Oz@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:wjvzQ8Vot1XEFwn7@xxxxxxxxxxxxxxxxxxxxxxx
Jill <news@xxxxxxxxxxxxxxxxxxxxx> writes

sorry - what isn't a common procedure?

mass culling

Have a quick google
There has been a lot of work on it globally and explorations of the
various
methods and their efficacy and "humanity" etc etc

We may not have to deal with it too often in an emergency situation -
thank
whomever you wish - but around the world they do

The poultry industry as a whole does on a daily basis
Dealing with Millions upon millions of cull layers / breeders each year is
a
monumental headache - on every level - cost, welfare, logistics



How did the Dutch deal with their c.30 million culled in 2003?



I have just found this which anyone with a passing interest might find
useful -- and does include nitrogen

http://www.efsa.eu.int/science/ahaw/ahaw_opinions/1145/ahaw_op_ej266_avianinfluenza_annex_en3.pdf

SCIENTIFIC REPORT
Animal health and welfare aspects of Avian Influenza
Adopted on 13/14 September 2005
p75
10.2.3.1 The culling methods used during the AI crisis situation in the
Netherlands and Belgium
During the recent outbreak of avian influenza in the Netherlands and Belgium
(as well as
one case in Germany), a variety of different methods were used to kill
poultry. There was
no one method that was suitable for each situation. The choice of culling
method
depended on the housing and the numbers of birds. 66% of all the birds were
culled by
the method of poultry-house gassing. This method was found to be appropriate
only for
birds housed in large buildings but not for smaller groups of chickens,
geese, ducks and
turkeys housed in half open houses. Many farms were unsuitable for
poultry-house
gassing, due to the fact that the animals were housed in cages or in
half-open stables.
Among a number of alternative widely used methods, animals were culled by
electrocution or by filling the containers holding the birds with at least
70% CO2.
(Gerritzen et al. 2004).
10.2.4 CULLING OPTIONS
10.2.4.1 Culling by hand in plastic bags
A widely used method in the South East Asian Region is culling the animals
by hand by
putting them in plastic bags and burning the bags. This method is
ineffective, inefficient,
Scientific report on animal health and welfare aspects of Avian Influenza
75
and unacceptable from an animal welfare point of view. It also poses a high
risk of
further virus spread.
10.2.4.2 Gassing (inhalation of agents)
Inhalation agents require the use of a sealed chamber such as commercial
waste disposal
bins that can be adequately sealed. The supervising veterinarian should be
able to see
inside the sealed container to ensure that the poultry are killed quickly
and effectively.
Large containers provide the opportunity to kill large numbers of birds
quickly.
Whenever birds are progressively added to large sealed containers, the
veterinary
supervisor needs to make sure that all birds inside the container are dead
before others are
added. Gassing in buildings or inappropriately designed containers always
carries the risk
that some birds will be exposed to low concentrations of gas or no gas at
all. If the gas
causes aversive reactions animal welfare will be compromised throughout the
exposure.
If bird carcasses are disposed of, for example by burning while some of the
birds are
conscious, welfare becomes very poor indeed.
Gases vary in their effects on bird welfare. Some are not detectable when
inhaled whilst
some are aversive. Some have effects after inhalation which are painful or
which
otherwise involve poor welfare. The speed with which birds are rendered
unconscious
varies, as does the risk of recovery before death.
Birds of different species also vary in their responses to gasses. In
particular, birds
adapted for diving, such as ducks, are able to hold their breath for longer
than birds not
thus adapted so may take much longer to become unconscious. If the gas
inhaled causes
aversive reactions, the period of poor welfare will be much longer in ducks
than it would
be in chickens.
Carbon dioxide (CO2)
CO2 is a colourless, virtually odourless, non-flammable, non-explosive gas
that presents
minimal hazards to operators. When inhaled it has an irritant effect and
produces a
choking sensation. All mammals and birds which have been tested show
aversion to this
gas (EFSA, 2004). CO2 is heavier than air, so it will accumulate in the
lower areas of the
location, building or container, where birds are placed.
CO2 kills poultry by depression of the central nervous system leading to
death by
hypoxia. Two common CO2 methods are currently in use:
a) Poultry-house gassing:
A commercial poultry-house is completely sealed off to two metres from the
ground and
slowly filled with compressed and vaporised gas. In 2003 in the Netherlands,
CO2 was
the gas that was used. The gas was pumped into the stable under high
pressure, slowly
filling the room. Practical experience with several operations showed that
after 35
minutes the birds started to die, the operation was completed in two to
three hours.
Poultry-house gassing has become a large highly advanced technology, using
mobile
evaporation equipment and specialised operators. Poultry-house gassing is
applied in the
case of large quantities of broilers, kept within mechanically ventilated
buildings.
The advantage is that large flocks of birds could be culled within a limited
amount of
time. Also limited training was needed for the collection of dead birds.
Scientific report on animal health and welfare aspects of Avian Influenza
76
One disadvantage of this method is that high additional costs are involved.
A second is
that the process cannot be stopped once it goes into action. Thirdly, the
introduction of
gas to a building will always be gradual so many birds will be exposed to a
low
concentration of gas for a lengthy period of time. Whilst the delay between
first contact
with the gas and unconsciousness is known for poultry introduced to a
container full of
gas, the delays which occur in poultry-house gassing will vary greatly but
are not known.
If it is an aversive gas, such as CO2, the welfare of the birds will be poor
for a period
which may last for many minutes. As described above, the birds could be in
contact with
the gas for as long as 30 minutes before becoming unconscious. Poultry-house
gassing
has been used mostly for housed broilers and young turkeys.
b) Wheelie-bin container gassing:
This system was developed by HKI-Wageningen and widely used during the AI
outbreak
in Europe, in 2003. The birds were culled in modified wheelie-bin
containers. The birds
were introduced into an atmosphere of 70% CO2, within the wheelie bin using
compressed gas from clustered cylinders. The birds were directly exposed to
the CO2,
leading to stunning within 30 seconds and culling after one minute.
Practical experience
has shown that if CO2 is decanted from compressed gas cylinders too quickly,
it will lead
to freezing of the gas in the cylinders, pipelines or of the regulators.
Also, considerably
more CO2 is required for birds with long necks (such as ducks) to ensure a
sufficient
amount of CO2 in the containers to kill these birds.
An advantage of the wheelie-bin container method is that it is not limited
to quantities or
type of poultry (up to a weight of 20 kg each). The culling process can be
stopped at any
moment, in case problems within the culling process occur.
One disadvantage of this system is the high costs of operation and the
limited
possibilities due to availability of sufficient CO2 cylinders, packed in
clusters of 12
containers each with the minimum weight of 1,200 kg per package, extra
transportation
of gas cylinders and forklift trucks for the transportation of the
wheelie-bins and cylinder
clusters. A second disadvantage is the poor welfare of birds during the time
from entry to
the gas to unconsciousness. There would be no such disadvantage if argon
were used.
The use of both CO2 methods is limited to areas with sufficient supply of
this gas and
under circumstances in which systems for the transportation of gas, gas
trucks, gas
equipment mobile evaporators as well as forklift trucks are available. This
means that the
use of CO2 gas is only possible in areas within the direct delivery
distance, so near major
cities.
The use of carbon dioxide is found to be very slow and often ineffective for
ducks and
similar problems are likely with geese. In one practical experience, most
ducks were still
alive after 3.5 hours in what was intended to be 40% carbon dioxide.
Carbon monoxide (CO)
Carbon monoxide is a colourless, odourless, non-flammable and non-explosive
gas. It
causes a fatal hypoxemia when levels reach 4 to 6%. It can be obtained in
compressed gas
cylinders. Carbon monoxide is toxic to humans, so there are significant
health and safety
issues that need to be considered. A well ventilated area is needed. The CO
system was
used during the AI outbreak in The Netherlands. The use of the CO method is
limited to
Scientific report on animal health and welfare aspects of Avian Influenza
77
areas with sufficient supply of this gas. Poultry-house gassing with CO is
complex and
dangerous for the operating personnel.
Nitrogen and Argon
Nitrogen and argon are colourless, odourless, non-explosive, non-flammable
gases that
present minimal hazards to operators. Both are available in compressed gas
cylinders and
are used in some commercial poultry slaughterhouses. They cause death by
hypoxia, but
are only effective when oxygen levels in the sealed container/chamber are
reduced to less
than 2%. Argon is a heavy gas like CO2 so can easily be introduced into a
container
where it will go to the bottom and displace air or nitrogen.
Hydrogen Cyanide
Hydrogen cyanide is a very quick and effective culling agent. It is reported
that poultry
may exhibit convulsions prior to death. It acts by causing paralysis of the
respiratory
centre. Hydrogen cyanide is very toxic to humans and is no longer
commercially
available.
Gaseous anaesthetics
Gaseous anaesthetics can rapidly induce anaesthesia leading to
unconsciousness and,
when applied at overdose levels, effectively kill birds by fatal depression
of the central
nervous system respiratory centre. Examples of gaseous anaesthetics include
halothane,
methoxyfluorane and isofluorane. They are far more costly than the agents
described
above. In most situations there are legal considerations regarding their
access and use.
These agents can induce anaesthesia in humans. They are not generally
considered
suitable for culling large numbers of poultry.
10.2.4.3 Injectable anaesthetics
Injectable anaesthetics depress the central nervous system leading to loss
of
consciousness, anaesthesia, apnoea, depression of the respiratory centre and
terminal
cardiac arrest. As is the case with the gaseous anaesthetics described
above, there are
legal considerations concerning their access and use. There are a number of
agents; the
most commonly used are the barbiturate drugs such as sodium pentobarbital.
They are effective agents when used at overdose levels to humanely kill
poultry.
Intravenous application is the preferred method. However in smaller birds
(without
prominent veins) intraperitoneal application is satisfactory. Intracardiac
application must
only be attempted when the poultry are fully restrained. The use of
injectable anaesthetics
may be limited to a veterinarian or appropriately trained persons under the
supervision of
a veterinarian. The use of this method is restricted to small flocks of
poultry.
Scientific report on animal health and welfare aspects of Avian Influenza
78
10.2.4.4 Physical Methods
Electrocution
Electrocution is used in many poultry slaughterhouses (water bath stunning
systems) to
stun birds prior to the severing of the major blood vessels of the neck,
which leads to
death by exsanguination.
If electrocution is to be used as the method of culling birds in an
emergency disease
outbreak, they will not die unless there is sufficient, constant current
(amperage) to cause
instantaneous and simultaneous destruction of the central nervous system and
cardiac
arrest. Using equipment to electrocute birds may be hazardous to personnel.
During the recent outbreak of Avian Influenza in the Netherlands, especially
designed
stand alone electrocution equipment was developed. The use of this equipment
proved to
be extremely effective and efficient enough to process 2,500 to 10,000 birds
per hour.
The electrocution equipment is available in different sizes, suitable for
different species
of birds. One mobile is specially designed for the use in rural areas. It
includes a
generator and is mobile. It can be placed directly on any spot within the
culling area. The
machine can process 2,500 to 4,000 birds per hour and is operated by one
local operator.
On site training of the operator takes approximately one day.
The use of mobile water-bath stunning equipment is subject to the same
problems for bird
welfare as those which occur in poultry slaughterhouses using shackling
lines and waterbath
stunning. It is stressful to birds to be caught by humans. When the birds
are carried
to the stunning or killing apparatus, the method of carrying is usually
stressful. Hanging
by the legs on a shackling line is stressful. Some birds may lift their
heads and are not
stunned or killed. If a shackling line is used, welfare will never be very
good and will
usually be considerably worse than it would be if killed by an inert gas in
a properly
designed container.
Electrocution using properly designed metal electrodes could be carried out
without
causing a substantial degree of poor welfare.
Cervical dislocation
Cervical dislocation can be an effective means of humanely culling poultry,
resulting in
the loss of central nervous system stimulation of respiration and
heart-beat. However, if
the technique is not performed correctly, birds may not be killed without
poor welfare
conditions prevailing.
This procedure may not be aesthetically pleasing. Cervical dislocation can
be performed
manually or using mechanical device, such as a Burdizzo castrator. Whenever
a large
numbers of chickens are to be destroyed, this may not be the method of
choice, but may
be the preferred option for long-necked birds such as ducks in small
numbers.
Decapitation
Decapitation results in a rapid loss of consciousness and blood loss. It is
an effective
method for culling poultry, but is not aesthetically pleasing. If sharp
instruments are not
used, injury and pain may result.
Scientific report on animal health and welfare aspects of Avian Influenza
79
Mechanical Maceration
Mechanical maceration results in instantaneous death. It has been applied in
some sectors
of the poultry industry for destruction of young birds, e.g. surplus day-old
male chickens.
This process is not aesthetically pleasing but with especially designed
equipment in good
working order it is humane for small birds such as day-old-chicks.
10.2.5 EFFECTS OF METHODS OF KILLING FOR DISEASE CONTROL ON

--
Malcolm


.

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