1. Principles of Restraining, Stunning and Slaughtering of Red Meat Species, and Critical Points in these Processes Mohan Raj BVSc, MVSc, PhD School of Veterinary Sciences University of Bristol Langford BS40 5DU United Kingdom M.Raj@bristol.ac.uk

2. Critical Points - Why? Slaughter involves conversion of conscious farm animals into human food Animals remain sentient until unconsciousness is induced by stunning Unconscious animals have capacity to regain consciousness until death is induced via blood loss at slaughter

3. Restraining Main purpose is to facilitate effective stunning Method should be appropriate for species and size of animals and stunning methods Severity of restraint should be kept to the minimum Duration should be as short as possible

4. Restraining Methods Stunning pens – cattle ‘V’ type – Sheep and pigs Band – Cattle, sheep, pigs

5. Stunning Method should be Appropriate for species Size of animals Throughput rate Appropriate for expected stun-to-stick (bleed out) interval Appropriate for blood vessels cut at slaughter Stun animals only when shackling, hoisting and bleeding can commence without delay

6. Slaughter Method should be Appropriate for species Throughput rate – Faster bleed out – rapid onset of death – higher throughput Appropriate for expected stun-to-stick (bleed out) interval Bleed out time (duration of bleeding)

7. Stun-to-stick interval - general As soon as possible – Cattle = 60 seconds – Sheep, goat and pigs = ideally 15 seconds, within 25 seconds Stop blood supply to the brain Longer stun-to-stick intervals for irreversible stunning methods

8. Recovery of consciousness – probable causes Delayed bleeding (long stun-to-stick interval, e.g. longer than 60s in cattle) Poor bleeding – Cutting veins rather than arteries – Blood clot – Constriction of vascular muscles Re-stun animals showing signs of recovery – return of rhythmic breathing Back-up stunner

9. Main Stunning Methods Mechanical – penetrating and non-penetrating captive bolts – Free bullets are rarely used in slaughterhouses Electrical – Head only or head-to-body Gas mixtures – Carbon dioxide, nitrogen, argon or mixtures

10. Mechanical Penetrating captive boltNon-penetrating captive bolt

11. Captive bolt stunners (e.g.) Different bolt lengths available to suit different species

12. Captive bolt stunning Critical Points Gun Cartridge Shooting position Stun-to-stick or bleed interval Blood vessels cut at slaughter

13. Gun and Cartridge Gun Appropriate for the species and size of animals Maintained and used according to manufacturers’ instructions Cartridge Appropriate for the species (e.g. colour coded) Stored properly - keep dry – Avoid high humidity / dampness

14. Captive Bolt Parameters Diameter Penetration depth Velocity Fired perpendicular (90 o ) to the skull bone Ensure bolt is completely retracted into the barrel before using – Clean thoroughly and replace parts, if necessary

15. Shooting positions Source: EFSA 2004 report Perpendicular or 90 o to the skull Pointing towards mouth Pointing towards throat Be aware of sinuses in large boars and sows Induce concussion and / or brain damage

16. CB stunning cattle Source: Temple Grandin

17. CBS – severity of brain damage Good stun Poor stun Source: Temple Grandin

18. Inadequate stunning – frequent causes Poor maintenance of gun and cartridge Inappropriate shooting position Rim of the bolt is blunt or disfigured NormalDisfiguredBlunt

19. Electrical stunning methods Head-only – Electrodes should span the brain Head-to-body – Electrodes should span the brain and heart

20. Electrical stunning - sheep Source: Humane Slaughter Association Wetting of wool helps to improve electrical contact and achieve effective stunning

21. Electrical stunning - sheep Source: Temple Grandin Manual

22. Electrical stunning - pigs Manual or automatic

23. Electrode positions – applied during manual stunning of pigs

24. Electrical stunning Control Points Stunner & electrodes Stunning parameters Stun-to-stick or bleed interval Blood vessels cut at slaughter

25. Stunner & electrodes Bad Good Source: Dr. Martin von Wenzlawowicz BSI, Postfach 1469, Germany

26. Stunning Electrodes Should be appropriate for the species and size of animals Should have good electrical conductivity – Minimum electrical resistance Avoid carbon build-up – Use wire brush to clean frequently during use

27. Stunners Out put – Constant voltage stunners – Constant voltage – constant current stunners – Variable voltage – constant current stunners

28. Constant voltage – slow rise time Note: time to reach maximum intended current (red) is slow, as the voltage remains the same (blue) at 300V

29. Constant voltage – quicker rise time Note: shorter time to reach maximum intended current (red), as the voltage remains the same (blue) at 350V

30. Constant current – variable voltage Note: Amplitude of current remains (lower trace) but initial voltage varies (upper trace)

31. Electrical stunning - parameters Waveform of current – Alternating current (AC) – Pulsed direct current (DC) Frequency of current (Hz) – 50 to 1500Hz Amount of voltage (V) & current (Amp) – Depends upon species and method

32. Electrical Waveforms (e.g) Sine and square wave alternating currents (AC) Pulsed direct current (pDC) Ask manufacturers’ for details

33. SW – AC frequency (Hz) Frequency HzPeriod ms 2005.00 4002.50 6001.67 8001.25 10001.00 12000.83 14000.71 Current (A) 012345 200Hz400Hz 600Hz 800Hz Period in milliseconds (ms=1000 / Hz) 0 0.2

34. Frequency Hz Period ms 2005.00 8001.25 14000.71 Current (A) 0 12345 Period in milliseconds (1000 / Hz) 0 0.2 200Hz 800Hz 1400Hz pDC frequency (Hz)

35. Effect of applied voltage on electrical impedance Defra (UK) funded project MH0110 & MH0111.

36. Effect of applied pressure on current profile Defra (UK) funded project MH0110 & MH0111.

37. Manual error (e.g.) N.G. Gregory Manual stunning is more variable than automatic stunning Current profiles

38. Gas mixtures Used for pigs (poultry) Eliminates need for restraint – group stunning in pigs Killing is better than stunning – Eliminates chances of recovery – Stun-to-stick interval is not critical – Reduces pressure on personnel

39. Gas mixture - basics Rate of induction of unconsciousness is related to concentration of gas – Low concentrations require long exposure times Duration of unconsciousness is related to gas concentration and duration of exposure Prolonged exposure to high concentrations result in irreversible stun – death in some animals

40. Gas stunned pigs Source: Temple Grandin Completely relaxed carcasses

41. Gas stunning Ensure smooth entry and passage of animals through the system No bunching or grouping of animals Gas concentrations monitored and maintained during exposure Visible and audible alarm systems Calibrate gas monitors

42. Loading / stunning systems for pigs Single race loading system Low stress group loading / stunning system Source: Temple Grandin

43. Gas stunning Interval between end of exposure to gas and bleeding last animal in a group should be appropriate and adequate to prevent return of consciousness Provision to monitor and deal with recovery of consciousness Back up stunners

44. Literature Safety and maintenance of electrical stunning equipment: http://www.hsa.org.uk/Resources/Publications/Technical%20Notes/TN5.pdf Stun-to-stick time: http://www.hsa.org.uk/Resources/Publications/Technical%20Notes/TN17.pdf Wotton, S.B. & O’Callaghan, M. 2002. Electrical stunning of pigs: the effect of applied voltage on impedance to current flow and the operation of a fail-safe device. Meat Science, 60: 203-208. Electrical stunning of sheep and pigs – a video presentation by Dr, Grandin: http://www.youtube.com/watch?v=-FEUfkmJQuA http://www.youtube.com/watch?v=-FEUfkmJQuA Visit www.grandin.comwww.grandin.com

45. Thank you