Small-Scale Poultry Stunning

1. Small-Scale Poultry Stunning Anne Fanatico, Ph.D. National Center for Appropriate Technology February 2009

2. Poultry are not included in Humane Slaughter Act However, Birds should be stunned before slaughter because they feel pain Electric stun is not a painful shock”, insensibility is instantaneous Birds should be insensible to pain at the time of slaughter Neck cut without stun, bird stays conscious for at least 15-30 seconds This suffering is avoidable.

3. Restrain Stun/Kill Bleed

4. Restraint/Immobilization Position the bird for kill/stun Protect carcass quality by reducing wing flapping and convulsions • Methods • Manual • Shackles • Kill cone Gas stun/kill generally uses a container

5. Humane slaughter • Slaughter that occurs without causing avoidable fear, anxiety, pain, suffering, distress • (Raj seminar) • Stun • Not required by law for poultry • Large plants: Universal (to immobilize bird and reduce carcass damage) • Small plants: Common • Small farms: Rare • Welfare programs require stunning • Birds feel pain and should be insensible at slaughter • Stun method should induce immediate loss of consciousness (Raj seminar) • Stun should be longer than time interval between stun and neck cut (at least 40s) • Zero tolerance for birds entering scalder alive • Religious kill does not stun: kosher or halal

6. Stunning and Immobilization Electric stunning immobilizes bird and positions it for automatic killer Stunning also reduces massive involuntary wing flapping and muscular activity that may damage carcass and meat quality

7. Types of Stun/kill • Electric • Waterbath, group • Whole body • Handheld, individual • Stun knife, whole body • Electrodes, head-only • Mechanical • Penetrative captive bolt • Nonpenetrative captive bolt (concussive) • Firearm with free projectile • Maceration (only for embryos and young chicks) • Cervical dislocation • Gas • Atmosphere

8. Electrical Electrical stun must be instantaneous Head only Causes a generalized epilepsy Severe wing flapping if unrestrained (Gregory, 2004) Whole body Exposes the body to a current generating a generalized epileptic form and, possibly, fibrillation or stopping of the heart (killing) Currents travel through paths of least resistance (skin, breast muscle, cardiac muscle, leg muscle (abdominal fat has greatest resistivity of tissues) As a result, muscle contractions (tonic spasms and tremors) are stimulated Heart and respiratory rates decrease and blood pressure increase (Bilgili 1992) Majority of current may pass through body (only 20% through head) (Raj seminar) Impact on meat quality

9. Signs of effective stun • Absence of rhythmic breathing • Absence of third eyelid reflex • Constant rapid body tremors • Wings held tight against body • Signs of effective kill • Absence of rhythmic breathing • Absence of third eyelid reflex • Wings droop • Dilated pupils • Signs of ineffective stun/kill • Rhythmic breathing • Tension in neck • Ability to control head • Third eyelid reflex Recoverable stun commonly used in US Regular breathing returns (signaled by return of abdominal movements in vent area) Bird should be cut and bled before recovery

10. Low voltage electric stun results in: Epileptic seizure phase All or nothing threshold event; Can occur as low as 8 mA (notes) Although 45 mA needed for effective immobilization (Bilgili 1992) Theorized that epileptic waveform are insensible to pain and are unconsciousness Humans who have experience of grand mal or epileptic seizure report no pain

11. Electrical circuit should be in form of a closed loop Electrical stun parameters Impact of waveform (AC, DC constant, DC pulsed) Impact of frequency (Hz, waveform per second) (household currents at 60 Hz) Impact of amount of current or amps (mA) or voltage (V) Period of time stun is applied Amps do the actual stunning

12. Electric Water bath Stun Causes epileptic waveform In Europe, causes cardiac arrest Electrical circuit passes through whole body

13. Electric Water bath Stun U.S. Low voltage stun used 30-60 V, 20-45 mA/bird Recoverable stun Europe High voltage stun used; stun to kill (for welfare reasons) 150 V, 100 mA/bird (Bigili, 1999) Causes 90% heart fibrillation Over 120 mA can cause carcass damage (Wilkins, 1999) However carcass and meat quality issues can result from high voltage stun Increased breast muscle hemorrhages Red wingtips Broken pectoral bones (clavicle, scapula) Use of high frequency can reduce problems (increase from 60 Hz to 500 Hz) However, birds only stunned rather than killed by cardiac arrest Use constant current rather than constant voltage (Raj seminar)

14. Electrical Water Bath Stun Welfare Issues Handling can be problematic: Dumping, inversion and shackling live birds Pre-stun shocks possible Inadequate stun possible Mis-stun (flock uniformity issues, insufficient feet-shackle contact (heavy scales on feet, not wetting feet-shackle contact point, wet birds (causes current to flow over surface of bird); high variation in resistivity of skull depending on thickness and density) Live birds may enter scalder; no red birds (associated with short bleed out time) Stunning monitors (anmeter) can help insure adequate stun (Gregory, 2004) Bleed for 90 s (Bilgili 1992)

15. Handheld Electrical Stunning Stun knife Electrical circuit passes through whole body Uses a metal grounded support (i.e. hang bird from a shackle Current runs through entire bird (whole body stun) Usually delivers about 200 mA, depends on setting Problem: There are no protocols for use with animal welfare in mind Little metering is done To determine volts and amps

16. Handheld electric stunner: Head Only Two electrode pads on forked handset Head-only stun Delivers 130 volts Available in Europe Problem: when converting to US Electricity, amps and volts may change

17. Captive bolt Stun/kill Cartridge-powered One person can restrain and stun birds Two people required for adult turkeys Generally used for euthansia Air-powered .22 Penetrating captive bolt Severe wing flapping; may be reduced in a cone maximum pressure of 135psi http://www.acclesandshelvoke.co.uk/cashpoultry.htm

18. Amount of air pressure needed for various bird types http://www.acclesandshelvoke.co.uk/cashpoultry.htm

19. Knocker head Convex or Flat http://www.acclesandshelvoke.co.uk/cashpoultry.htm

20. Position instrument at right angle to skull Hold beak loosely; release grip when firing http://www.acclesandshelvoke.co.uk/cashpoultry.htm

21. Flat or convex knocker head http://www.acclesandshelvoke.co.uk/cashpoultry.htm

22. Cartridge components must be cleaned after use http://www.acclesandshelvoke.co.uk/cashpoultry.htm

23. http://www.acclesandshelvoke.co.uk/cashpoultry.htm

24. Captive Bolt: Concussive Zephyr Stun Gun for Rabbits Modified nail gun Compressed air-driven, non-penetrating captive bolt to humanely stun rabbits Place stun gun between ears at top of skull Use minimum of 55 PSI Large rabbits: Increase PSI Two shots in quick succession Zephyr is 99.6% effective when used correctly

25. Nonpenetrating captive bolt; concussive Bleed animal quickly before consciousness returns Not recommended for euthanasia because animal may return to consciousness Modified nail gun vs captive bolt gun Nail gun pushes; must hold head Leaves wound size of quarter; little bleeding

26. Gas stunning Large scale Advantages: Less handling Birds can be killed in coop No inversion or shackling of live birds

27. Gas-stun Small scale Containerized http://www.fpmne.com/ Gas cart

28. Gas approaches Use argon/nitrogen with no more than 2% oxygen Use argon/nitrogen mixture with no more than 30% CO2 and no more than 2% oxygen High levels of CO2 (above 30%) is aversive to birds; causes breathlessness; acid is produced Anoxia (lack of oxygen) Leads to carcass convulsions after bird is unconscious (carcass damage) The use of CO2 at low levels can help reduce motor activity Two phase approach Uses CO2 at 30% for anesthesia and then increases to 80% for euthanasia

29. What if you don’t have any stunning equipment? • Cervical dislocation • Rapid decapitation • (Not universally accepted as humane) • (Practice with anesthetized birds; discard meat) • Spinal cord is severed • Carcass issues • Wing flapping, violent muscular contractions • Broken wings, poor bleeding, red discoloration (McNeal, 2003) • Meat quality issues • Convulsions involving wing flapping associated with acceleration in breast • muscle ATP and glycogen depletion and poor water-holding capacity Watch cervical dislocation demonstration on Humane Slaughter Association video

30. Impact of stunning on body movement (McNeal 2003) Reaction scores 1 = none to mild muscle quivering 2 = mild wing flapping 3 = moderate spasmodic body movement and full wing flapping 4 = violent wing flapping and full-body movement capable of damaging carcass Results: Body movements that can lead to carcass damage are more violent with decapitation than neck cut; stunning reduces wing flapping and muscle contractions compared to decapitation and neck cut

31. Not stunning Neck cut: Bird usually loses consciousness within 15 s, but some birds conscious for 30 s (Gregory, 2004) Decapitation: loss of brain activity within 15 s (McNeal, 2003)

32. Factors to consider in stunning/not stunning • Operator welfare • Bird welfare • Bleed out/carcass damage • Meat quality

33. Bleeding Efficiency • At neck cut, blood shunted to organs in attempt to maintain homeostasis; only about • half of the volume is lost • Bleeding efficiency depends on • Blood vessels that are severed • Ventral cut: cuts 4 blood vessels (2 carotid; 2 jugular) • Bilateral cut: only cuts 2 vessels (slower bleeding) • Size of cut • Orientation of carcass (vertical position) • Stun • Low voltage: muscle contractions force blood away from skeletal muscle • towards large vessels for more efficient bleeding • Cardiac arrest can slow bleed out but doesn’t necessarily reduce blood • loss (Gregory)

34. Bleeding Efficiency Source Newell and Shaffer (1950)

35. Meat Quality Basics • Conversion of muscle to meat • Based on biochemistry • Muscle evolved for locomotion • Muscle contracts, myofibrils interlock (sliding filament); cross bridges form • Muscle does not die immediate at death of animal • ATP is required to break crossbridges of myofibrils • Rigor mortis occurs because myofibril crossbridges cannot be broken after • ATP used up; (until proteins start to degrade) • Meat quality factors • pH • Water-holding capacity • Texture, tenderness • Color • Nutrients • Shelf life

36. Impact of Stress on Meat Quality Dark, firm, dry meat (DFD) Stress sensitive birds may exhaust glycogen stores and, after death, experience little pH reduction due to low production of lactic acid. This can lead to dark, firm, dry meat that has a high ultimate pH and is susceptible to bacterial growth and has a short shelf life. or Pale, soft, exudative meat (PSE) Accelerated metabolism which, when occurring in a carcass that is still warm, can lead to denaturation of protein and PSE-type meat with poor water holding capacity and a low ultimate pH.

37. Rate and extent of pH decline Rate: You don’t want pH to go down too fast while muscle is hot or denaturation occurs (PSE) Degree: You don’t want the pH to be too low (it might get to the isoelectric point) You don’t want the pH too high (poor shelf life) Electric stunning slows rigor