MECHANICAL STUNNING of PIGS AND SHEEP AND GAS STUNNING/KILLING OF PIGS

MECHANICAL STUNNING of PIGS AND SHEEP AND GAS STUNNING/KILLING OF PIGS

DEFINITION OF STUNNING Stunning is any intentionally induced process which causes loss of consciousness and sensibility without pain Mechanical stunning equipment delivers blow to the head of an animal at 60-75 m/sec, stuns animal within 5-8 ms (and makes nerves dysfunctional). Speed for sensory pathways to brain is 50-80ms

PURPOSE OF MECHANICAL STUNNING To render animal unconscious so it does not feel any pain ( insensible ) To enable further safe and prompt killing of an animal while it is unconscious. Unconsciousness means animal cannot be aware of any peripheral stimuli, including pain

MECHANICAL STUNNING Mechanical stunning requires a delivery of energy to brain in order to affect immediate (temporary or permanent ) dysfunction of the brain and so render insensibility Delivery of that energy inside skull due to propagation of compression-rarefaction wave in cerebral fluid Sources of energy when mechanical stunning is used - gun powder or other explosives - compressed air pressure EQUIPMENT = CAPTIVE BOLT STUNNING GUN

TWO KEY ELEMENTS ENERGY OR ENOUGH POWER - Energy = kinetic energy that hits the brain CORRECT POSITION - Position where maximum impact can be expected

RESTRAINT OF SHEEP PRIOR Restraint same principles as in electrical stunning Restrainer conveyer Group pen

On the top of the head in the midline position aiming straight down POSITION 1 (source HSA, 2006)

POSITION 2 Behind the ridge of horns while aiming to the base of tongue (source HSA, 2006)

POWER Appropriate size of cartridges according to the producer s guidelines

Immediate collapse POST STUNNING No rhythmical breathing Eyes wide open No corneal reflex Tonic phase ( 10 20 seconds) Clonic phase IF RHYTHMIC BREATHING OR KICKING are observed immediately post stunning MUST STUN AGAIN!!!!

(source HSA) RECAPITULATION VIDEO

BLEEDING Even chance of recovery is low, sheep must be bled as soon as possible after stunning Usually in first 10 seconds within the tonic phase It is important that all major blood vessels are severed.

MECHANICAL STUNNING OF PIGS Should not be used routinely for commercial purposes Might be used for emergency slaughter/killing of animals that cannot move or other emergency situations. Reasons??????? Small volume of a pig brain Large skull and thick frontal bones (up to 4 cm) well protecting pig s brain Vigorous and long lasting clonic phase Source: HSA, 2006

VIGOROUS CLONIC PHASE AFTER MECHANICAL STUNNING

CAPTIVE BOLT IN PIGS Source: HSA, 2006

CAPTIVE BOLT STUNNING ATTRIBUTES OF CORRECT STUNNING. Correct position of gun Correct angle Proper triggering followed by hit Animal collapses immediately Absent peripheral sensitivity Absent corneal reflex Vigorous clonic phase ( very strong kicking) If eyelids are wide open the animal is dead!!!!! NO RHYTHMIC BREATHING!!!!

CAPTIVE BOLT STUNNING INCORRECT STUNNING Incorrect position of stunner on skull Stunning device misfires or insufficient velocity: Wrong cartridge Poor gun maintenance Damp powder Animal does not collapse Eyes are rolled out Standing kicking or escape behaviour!!!!! RHYTHMIC BREATHING!!!!

EQUIPMENT FOR MECHANICAL STUNNING

A Bolt B Stop washer C Recuperative Sleeves D Flange Washer,E Flange F Piston G Combustion Chamber H Breech I Cartridge J Firing Block K Hammer L Undercut M Trigger N Barrel

Stunning equipment - Magnum knocker

DAILY CLEANING MAINTENANCE - Clean barrel from inside and outside - Clean bolt - Clean recuperative sleeves and washers WEEKLY MAINTENANCE - Clean expansion chamber (carbon buildup) REGULAR SERVICING - replace sleeves, washers etc. before efficiency is reduced

VIDEO - MAINTENANCE

GAS STUNNING/KILLING ADVANTAGES - meat quality - easy handling systems (Butina) DISADVANTAGES - aversive reactions of pigs to high concentrations of CO2 / respiratory distress

CO2 AND ITS MIXTURES CO2 is heavier than air therefore in chambers (in mixtures with air or oxygen) is usually located on the bottom of the chamber Therefore principle of moving pigs on the bottom of the pit ( gas chamber) are used

HOW DOES IT WORK When animal is placed into atmosphere with a higher concentration of CO2 CO2 replaces Oxygen in the respiratory and circulatory system which causes acute lack of oxygen in CNS /unconsciousness and brain death. Gas stun/kill is neither immediate nor induction is without stress Raj and Gregory (1995) found that pigs withdrew from an atmosphere of 90% CO2 in less than 5 sec

KEY PARAMETERS Concentration of CO2 - With increased concentration of the CO2 in the atmosphere, shorter time of exposure is needed to stun an animal - When same period of exposure applies unconsciousness increases with the concentration of the CO2 Time of exposure - In practice: from 80 250 sec. - EFSA recommendation : optimum exposure time of 100 sec should be mandatory for all systems. - GONDOLA WITH PIGS MUST REACH THE BOTTOM OF PIT PLACE WITH HIGHEST CONCENTRATION WITHIN 30 SECONDS FROM ENTERING THE CHAMBER.

GAS STUNNING SYSTEMS DIP LIFT SYSTEM PATER NOSTER SYSTEM

MONITORING OF CO2 Carbon dioxide concentrations should be monitored AND DISPLAYED continuously: A) IN PATERNOSTER - above the pig s head while standing, at both 1st stop position and bottom position. At the bottom - 0.2 m above floor level of the gondola. B) IN A DIP LIFT at the position the gondola reaches after 10 sec in dip-lift systems - 0.6 m above floor level of the gondola A clearly audible or visible warning must be given if the carbon dioxide concentration falls below the required levels.

SIGNS OF UNCONSCIOUSNESS The stunning efficiency shall be monitored regularly so no pigs regain consciousness during sticking or bleeding. Signs of unconsciousness are: Lateral recumbency Absence of rhythmic breathing. Gagging or gasping may be present briefly. No convulsions present. Absence of spontaneous blinking of the eye. Corneal reflex may be present briefly in a low frequency (<5%) of the total number of pigs, provided that other reflexes are absent.

RETURN TO CONSCIOUSNESS

BLEEDING AND STUN TO STICK INTERVALS In experiments 1 min of exposure to 80% carbon dioxide induced unconsciousness lasting about 1 min. In another study the recovery from exposure to 90% carbon dioxide was approximately 60 to 90 sec. Basic principle is to stick as soon as possible Time of exposure 90% (sec) Sticking within (sec) 100 30 120 30 130 60

GOOD PRACTICE In dip-lift and pater-noster systems, pigs shall be exposed to a minimum 80% carbon dioxide within 10 sec from leaving atmospheric air. The carbon dioxide concentration at the bottom of the pit shall be a minimum 90%. Exposure time to carbon dioxide shall be sufficient to ensure that no pigs regain consciousness before death supervenes through bleeding. A minimum exposure time, which cannot be shortened by the personnel, appropriate to the concentration gradient in the pit must be set.

DIP LIFT SYSTEM

PATER-NOSTER

AUTOMATIC DRIVEWAY SYSTEM

THE ADVANTAGES OF DRIVING THE PIGS IN AUTOMATIC No contact with personnel Low noise level Minimal shadows Adjustable pressure Variable driving speed Synchronization with CO2 stunning system

AUTOMATIC DRIVEWAY SYSTEM Model Butina Push Hoist Gates (PHG) Speed forward m/s 0,25-0,50 Total time Sec. 62-39 Capacity of the handling system / pigs pr. hour: 870-1380

HOW ABOUT THAT? Midas stunning system with three-electrode stunning capacity 300 700 animals per hour

OLD STYLE HANDLING SYSTEMS

BUTINA SYSTEM

Questions??

THANK YOU FOR YOUR ATTENTION Organisation mondiale de la santé animale World Organisation for Animal Health Organización Mundial de Sanidad Animal 12 rue de Prony, 75017 Paris, France - www.oie.int oie@oie.int