On-Farm K i l l ing Of Poul t ry Using Gas – UK Ex per ienc es

David Pr i t c hardGordon Hic k m an23 J anuary 2007

Overv iew

Recent developments & UK experience of:q R&D Programme of physiology of gas

mixtures q Containerised Gassing Units (CGUs)q Whole House Gassing (WHG)q Foam

Bac k ground

q Permissible techniques for killing birds for disease control (WASK, schedule 9):yDislocation of the neck (NB OIE

code)yDecapitationyLethal injectionyFree bullet XXXyElectrocutionyExposure to lethal gasesyPercussion killer

Bac k ground - Wheel ie B ins

q Use Carbon dioxideq Welfare issues: gas, bird

monitoring, physical trauma & crushing; smothering

q Technical issues: ygas supply ytemperature

q Consequently there was a perceived need for an improved system that addressed some of the welfare and technical issues presented by the wheelie bin system

R& D – Modi f ied Bins

q Study initiated at Bristol University - “Emergency Killing of Poultry on Farm using Gas Mixture”

q Led by Dr Mohan Rajq Major objectives

yInvestigate alternatives to CO2

yModify design of binyExamine rates of filling with

gas in a variety of circumstances

R& D - Al t ernat ive gases

qAvailable gases:y inert gases (argon,

nitrogen);y inert gases + CO2;y carbon monoxide;y cyanide

qAversiveness of gas mixtures

qSelected: Ar: CO2 in an 80:20 mixyWelfare; ycost;y availability; ypracticality; yhealth & safety

Conc ept Developm ent (CGU)

q Subsequent “brainstorming”resulted in birth of the Containerised Gassing Unit or CGU

q Principle of ramping up usual procedures during crisisyUse available catching teamsyUse available Poultry transport

module and cratesq Principle of simple robust

systemsyGas tight containerySupply of argon/CO2yMonitoring equipment - Oxygen

meter

Cont a iner ised Gass ing Uni tq The containerised gassing units consist of a gas

- tight steel (3mm thick) container (1.5m W x 3.0m L x 1.5 H = 6.75m3)

q A number of standard poultry transport modulesq A supply of a 80% argon and 20% carbon

dioxide gas mix.

q2 CGUs and 6 modules stored on an articulated trailer for rapid response

q Gas sourced separately

qBoth deployed in less than 24 hours

q50 CGUs in total

Port ab le Syst em for Rapid Deploym ent

q The container is pre-fitted with gas pipe work and diffusers to disperse gas and reduce noise and are secured to the metal container.

q Each container comes with two gas regulatorsand a manifold

q For transport these are securely attached to inside back panel of CGU

q A rack full of individual gas cylinders

qManifold system and gas regulators

q One standard chicken transport module containing poultry are placed inside the CGU using a forklift

q Capacity depends on size of bird

q 12 drawers each with 25 birds = 300 chickens per unit

q The door is shut and secured.

q The gas supply is turned on and maintained at 3 bar delivery pressure for up to three minutes or until a residual oxygen of 5% by volume is registered in the oxygen analyser.

q The birds are held in the gas mixture for up to five minutes from the moment of turning the gas on or until wing flapping has stopped (as determined from listening to the sound)

Oxygen analyser

q A forklift is used to remove the module full of birds and it is placed in atmospheric air.

q Each draw is pulled out and examined to check that there are no survivors.

qAfter checking for survivors, carcases are sprayed with disinfectant

q The dead birds are emptied into bags or direct into leak-proof lorries

q Self-emptying modules can be used to minimise manual handling

Each module will hold about 300 chickens (2 kg)q CGU can be filled in 2 minutes and an additional 30

seconds exposure to gas mixture will effectively kill the birds

q Operating with two metal containers on a farm would therefore facilitate killing 600 chickens in 5 minutes

q Allowing an interval of 5 minutes between each cycle, for the purpose of unloading and reloading metal containers with modules, would in theory allow the killing 6,000 birds per hour.

Work ing Assum pt ions

q For planning purposes a maximum throughput of 4,000 birds per hour is used.

q Incidentally, a catching team of 5 people can also work at the rate of crating 6,000 birds per hour

q Therefore, one catching team could supply birds to operate two containers on each farm.

Work ing Assum pt ions

Fie ld ex per ienc e w i t h CGUs

qOver 120 staff trained using DVD, SOP and practical course

qUsed on three farms in Norfolk LPAI outbreak with about 48,700 birds killed in less than 48 hours

qUsed for East Lothian NDV outbreak for 12745 birds ( partridge, quail, pheasant chicken)

qPlanned throughput achieved with safe operation and humane kill

qPositive media coverage

Cont a iner ised Gassing Uni t sStrengthsq Used in last 2 UK poultry disease outbreaksq Modest costq Proven techniqueq Humane – non-aversive gas mixq FlexibleWeaknessq Individual birds need to be handledq H&S associated with use of gasq Moderate throughput Usesq Medium sized units (10 - 20,000 birds)q Free range and Caged units

Whole House Gass ing Tr ia l

qBirds being culled for disease reasonsqNE England October 2006qUsing liquid Carbon dioxide direct injection into the houseq to kill 13,000 chicken poults

Rec ord ing probes for gas &Tem perat ure

Preparat ion of houseHouse m easuredLengt h 30 mWidt h 12 mHeight t o

r idge 4m

Plac ingBiosec ur i t y and Safet y Barr iers

Preparat ion

Trailer with variable height assembly for lance fitted with high pressure hose

( pressure over 5 bar)

Preparation of site and presite briefing

Closed inlet flaps in side walls immediately prior to gas delivery

Del ivery lanc eLance placed at approximately 1.5 meters above floor

End of lance cut at 30 0to direct gas to roof of house

Temperature probe in situ

Video Moni t or ing us ing IR c am eras

Gas del ivery equipm ent and s t a f f

Gas m oni t or ingPersonal Carbon dioxide meter Continuous gas monitor

Perimeter security

Gas Del ivery t o House

4 Tons of Liquid CO2 delivered in 4 minutes

Housed closed for 1 hour

Safet y Chec k sPost gass ing

Operatives work in pairs for safety

Engineers using Breathing apparatus used to check gas levels to certify safe entry for vet to check birds are killed

Ind ic at ors o f hum ane k i l l observed post c u l l

qDistribution of birds e.g. clumping or stacking of birds indicating signs of panic or suffocation

qPosition of birds post cull – lateral recumbency or supine or ventral

qExternal signs on birds of injury or damqSigns of convulsions e.g. disturbed litter

Dist r ibut ion of b i rds post k i l l

Ventral recumbency

Lateral recumbency

No signs of convulsions

Com par ing d is t r ibut ion before and af t er gas de l ivery

Before - showing free dispersion

After - showing a small amount of clumping

Post k i l l d is t r ibut ion

qBarrier placed half way down house to limit clumping

qSome clumping was seen around barrier Indicating that birds did move away from source of gas

Liqu id Carbon d iox ide k i l l ing of poul t s - Conc lus ionsqGood preparation of house – removal of

furniture and feeding systems and barrier put in place

qEffective delivery systems 4 minutes to 50% CO2 at 1.5 meters high

qNo evidence of poor welfare such as injury, suffocation, or convulsions

qSome evidence of movement from the incoming gas stream

qHumane acceptable system of killing small chickens

Gassing – w hole houseStrengthsq Widely used in Holland and Canada q Live birds do not need to be handledq Large numbers can be killed quicklyq Humane

Weaknessq Need technical supportq H&S associated with use of gasq Large quantity of gas requiredq Limited range of houses suitable ?

q Usesq Large broiler unitsq Some caged units?

Low Densi t y Foam For K i l l ing Poul t ry On-Farm

Using n i t rogen or s im i lar anox ic gas m ix t ure

Low densi t y foam For K i l l ing Poul t ry On-Farm

q Still under developmentqDetails subject to commercial confidentialityq Low density foam as a carrier for anoxic gasq Death by exposure to anoxic gas mixture and

not by physical obstruction of trachea/lungsq Trials using nitrogen and carbon dioxideq Trials using small buildingsq Laboratory scale trials with animals

Foam generat ionq Low density foam

produced using standard fire fighting foam generator from surfactant and water

q Instead of air, anoxic gas is used to create bubbles

q Surfactant specification and quantity is the key

q Fragile dry foam needed not not strong wet foam

Liqu id Ni t rogen & Vapor iser

qNitrogen is cheaper, readily available and non-aversive

qNitrogen has a higher boiling point and can be vaporised more easily than carbon dioxide

Gas Del ivery

q Gas (not liquid) delivered to foam generator at close to ambient temperature

qFoam rapidly fills building

Pr inc ip les

q Foam surfactant must be robust enough to hold gas and fill building to required height

BUT

q Fragile enough so that bird movement breaks bubble and releases gas

q accepted by the birdsq Further development required before it can be considered for practical on-farm use

Ac k now ledgem ent s

Thank s t o qBristol UniversityqRoslin InstituteqSilsoe Research Institute and University of

LondonqCommercial partners and poultry farmers qState veterinary service staff who developed

practical training and lead field operationsqDefra colleagues in AWD