Dorothy McKeegan presented on October 2011 her study: High Expansion Gas-foam: a humane agent for emergency killing of poultry? Dorothy McKeegan studied Zoology at the University of Glasgow before completing the MSc in Applied Animal Behaviour and Animal Welfare at Edinburgh University. After gaining her PhD in 1999, she worked at Roslin Institute near Edinburgh, conducting neurophysiological and behavioural research relating to the welfare of poultry. Dorothy was appointed as the BVA Animal Welfare Foundation lecturer at Glasgow in February 2005, and her teaching role involves delivering an integrated teaching programme for animal welfare and ethics across the undergraduate curriculum. As a member of the Division of Animal Production and Public Health, Dorothy continues to pursue her research interests in avian sensory physiology, pain perception and poultry welfare. In current projects she is investigating avian pain, humane emergency slaughter and the welfare implications of production-related conditions. Dorothy also has an educational research interest in the teaching and assessment of ethical reasoning in veterinary students.

1. 10/21/2011
1
High Expansion Gas-foam: a
humane agent for emergency
killing of poultry?
DEF McKeegan, MA Gerritzen, JM Sparrey,
TGM Demmers and CM Wathes
Background
• Ongoing threat posed by Avian Influenza requires the
availability of rapid, practical and humane methods of
emergency killing for poultry
• Range of methods developed
• Considerations
• Practicality
• Cost
• Availability for rapid deployment
• Disease transmission risk
• Welfare consequences

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2
Emergency killing methods
• Containerised Gassing Units
• Flexible but birds must be handled
• Slow throughput
• Whole house gassing
• Birds killed in their production housing
• No handling
• CO2 availability?
• Ventilation Shutdown
• Controversial, available only as a last resort
• Foam (in development)
• Potential to use inert gases
• In situ killing without sealing buildings
Foam as an emergency killing method
• Use of low expansion foam for
emergency killing in the USA has
been criticised on welfare grounds
as its mode of operation is occlusion
of the airway
• We investigated the welfare
implications of application of high
expansion foam, intended as a gas
delivery method
• Examined in laboratory studies
involving individual birds and
groups, with Nitrogen and Carbon
dioxide filled foam

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• Hens, broilers, ducks and turkeys
• Surgery to implant EEG electrodes
then recovery
• Individually exposed to foam filled
with air (control), nitrogen or carbon
dioxide in a 1m3 Perspex box
• Foam introduced from above with
hand held generator
• EEG and ECG continuously
monitored – baseline and during
exposure – via a logger worn in a
lycra backpack
• Cameras to the side and below,
oxygen sensors in corner of the box
at 10 cm, 30 cm and 90 cm
Individual trials - methods
Telemetry/logging unit

4. 10/21/2011
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Hen trials – Oxygen concentrations in N2 foam
Results - heart rate responses to foam in hens
0
100
200
300
400
500
-200 -150 -100 -50 0 50 100 150 200 250
Time (s)
Heartrate(bpm)
0
100
200
300
400
500
-200 -150 -100 -50 0 50 100 150 200 250
Time (s)
Heartrate(bpm)
Air filled foam (control) Nitrogen filled foam
F FS S S S M M
M - MotionlessS - SubmergedF – Foam start
Hen trials – Oxygen concentrations in N2 foam
EEG responses to nitrogen filled foam (UK)
6.0 36.2 36.4 36.6 36.8 37.0 37.2 37.4 37.6 37.8
s
375.6 375.8 376.0 376.2 376.4 376.6 376.8 377.0 377.2 377.4
s
Baseline
Transitional
Transitional Suppressed Isoelectric
Hens
Mean(± SD)
9.8 ± 2.8 30.1 ± 6.8 65.7 ± 11.5
Broilers
Mean(± SD) 8.3 ± 4.4 17.6 ± 3.5 46.9 ± 8.3
Time taken (s) to reach EEG phases in relation to submersion

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Transitional Suppressed Isoelectric
Broilers CO2 -2 ± 4 16 ± 2 66 ± 25
Ducks CO2 -11 ± 2 1 ± 2 58 ± 24
Turkeys CO2 -2 ± 3a 15 ± 4 60 ± 8
EEG responses to carbon dioxide filled foam (NL)
Time taken (s) to reach EEG phases in relation to submersion
Hen trials – Oxygen concentrations in N2 foam
Behavioural responses to nitrogen foam
Headshakes
Ataxia/loss of
posture (s)
Flapping
onset (s)
Flapping
bouts
Flapping
duration (s)
Time to
motionless (s)
Hens
Mean
± SD
2.0 ± 1.8 15.5 ± 3.9 17.8 ± 3.9 3.9 ± 1.4 13.7 ± 4.2 65.2 ± 10.9
Range 0 – 6 10 - 23 13 – 24 2 – 6 5 – 21 43 – 81
Broilers
Mean
± SD
2.4 ± 2.1 9.2 ± 4.0 15.3 ± 4.7 3.6 ± 1.0 13.7 ± 5.5 51.4 ± 7.6
Range 0 – 7 0 – 14 10 – 23 2 – 5 6 – 20 40 – 64
T test NS P = 0.001 NS NS NS P = 0.004
Timings in relation to submersion

6. 10/21/2011
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Hen trials – Oxygen concentrations in N2 foam
Behavioural responses to CO2 foam (NL)
Gasping
(s)
Headshaking
(s)
Ataxia/loss of
posture (s)
Flapping
onset (s)
Time to
motionless (s)
Broilers 25 ± 6 23 ± 1 54 ± 16 65 ± 15 54 ± 15
Ducks 13 ± 4 10 ± 3 38 ± 10 43 ± 7 69 ± 21
Turkeys 14 ± 2 10 ± 7 47 ± 7 63 ± 19 60 ± 20
Timings (mean ± SD) in relation to foam onset
Individual bird trials – Results summary (1)
• Immersion in high expansion foam filled with
nitrogen or carbon dioxide achieved a rapid
and humane euthanasia, with broadly similar
responses in all species
• Carbon dioxide foam was slightly faster
acting, little response to immersion in air filled
foam
• Behavioural responses included headshaking,
loss of posture and vigorous wing flapping
characteristic of anoxic death
• Mean time to loss consciousness was 18-30 s
with N2 and up to 16 s with CO2

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Individual bird trials – Results summary (2)
• Foam did not occlude the airway
(confirmed by PM)
• Mode of action is anoxia (regardless of
gas used to make the foam), nitrogen
produced more consistent foam
• Wing flapping quickly destroyed high
expansion foam
• Height of foam achieved above the bird
before wing flapping begins is crucial –
60cm required – to retain foam covering
and prevent re-exposure to air
Group trials - methods
Cameras
Foam
generatorsLongitudinal pen
Lateral pen
• 4 trials with broilers (192-360 birds per trial), nitrogen filled foam
• 2 pen configurations (lateral or longitudinal)
• 2 stocking densities (40kg/m2 or 50kg/m2)
• 4 foam generators (achieving 42.5 m3 foam /min)
• 8 video cameras recorded the progress of foam
• In each trial, 3 instrumented birds were monitored (EEG and
ECG)

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Group trials - Foam parameters
Trial 1 Trial 2 Trial 3 Trial 4
Stocking density (kg/m2) 40 40 50 50
Number of birds 192 192 240 360
Pen arrangement Lateral Longitudinal Lateral Longitudinal
Calculated foam generated (m3) 98 102 107 96
Final foam at end of run (m3) 86 96 89 86
Estimated foam destroyed (m3) 12 6 18 10
Foam destroyed (m3 per 100
birds)
6.2 3.0 7.5 3.3
Expansion rate 346:1 350:1 337:1 342:1
Group trials – ECG responses
50kg/m
2
0
50
100
150
200
250
300
350
400
450
500
-300 -250 -200 -150 -100 -50 0 50 100 150 200 250 300
Time (s)
Heartrate(bpm)
F – Foam start
S - First and last
submersion
F S S

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Group trials – EEG and behavioural responses
Time to reach EEG phases* Transitional Suppressed Isoelectric
40kg / m2 Mean ± SD 5.8 ± 2.0 24.1 ± 5.8 39.8 ± 3.0
50kg / m2 Mean ± SD 4.2 ± 3.3 19.7 ± 6.5 51.7 ± 14.8
Wing flapping Flap onset (s)*
Number of
bouts
Total duration
(s)
40Kg / m2 Mean ± SD 3.8 ± 2.3 3.2 ± 0.8 14.8 ± 5.9
50Kg / m2 Mean ± SD 5.1 ± 5.0 3.3 ± 1.7 13.9 ± 4.7
*in relation to submersion
Group trials – Results summary (1)
• The quantity and depth of foam delivered was sufficient to
keep the birds covered during wing flapping - the foam front
was consistently higher than 40 cm and built up to a minimum
of 50-60 cm within15 seconds of submersion
• The width of the pen of birds had a greater effect on the
amount of foam destroyed than the distance it had to travel
over the birds - suggests that it is the width of a poultry shed
that will determine the volumetric flow rate of foam

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Group trials – Results summary (2)
• The stocking density of the birds did not greatly affect foam
destruction rate, but movement of the birds away from the
approaching foam meant that the actual stocking density at the time
of submersion was usually maximal
• Patterns of behavioural change and onset of changes in EEG
characteristics closely matched those observed in individual bird
trials
• Foam as deployed in these larger trials delivered a reliable and
humane anoxic kill which was robust even at maximal stocking
densities
• An advantage of the foam system means that large houses can be
treated in sections, leaving birds in other areas unaffected
Gas filled foam – a humane agent?
• Collectively, the results show that anoxic foam has the
potential to be a reliable and humane method of emergency
killing for poultry
• Particular attention must be paid to foam quality and
production rates must be sufficient to achieve the required
foam height over birds to combat the destructive effects of
wing flapping
• The method has particular advantages for systems which
would not be suitable for whole house gassing
• The industry are supportive of the approach and a proposal to
produce and test a full scale on-farm system in the UK (which
will be available for disease outbreaks) is currently under
consideration

11. 10/21/2011
11
Acknowledgements
• Joint project by Glasgow University, RVC and Wageningen UR
• Funded by Defra (UK) and Dutch Ministry of EL&I (NL)
• Livestock treatment (Frans Withoos)
• Livetec (Jules Sparrey)
• Ajax fire fighting equipment
Contact:
Dorothy.McKeegan@glasgow.ac.uk
Marien.Gerritzen@wur.nl