Operational guideline: Humane slaughter guidelines for mammalian food animals

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1.0 Purpose

The purpose of this document is to provide guidance to Canadian Food Inspection Agency (CFIA) Inspection Staff on humane slaughter of mammalian food animals, including rabbits.

This document is intended to be used in conjunction with other guidance documents as referenced in section 3.0 since it is limited to information not included in these documents.

The guidance outlined below should be used when verifying compliance with regulatory requirements related to humane slaughter activities of mammalian food animals including rabbits.

2.0 Authorities

The inspection powers, control actions and enforcement actions authorized by the above legislation are identified and explained in the Food regulatory response guidelines.

3.0 Reference documents

4.0 Definitions

Unless specified below, definitions are located in either the:

Additional technical definitions are located in the Mechanical, electrical, gas stunning, slaughter methods and monitoring signs of unconsciousness or consciousness.

5.0 Acronyms

Acronyms are spelled out the first time they are used in this document and are consolidated in the food business line acronyms list (under development).

6.0 Operational guideline

The legal framework for humane stunning and slaughter of food animals is sections 141, 142, 143(1) and 143(2) of the Safe Food for Canadians Regulations (SFCR). Other applicable SFCR regulatory provisions include sections 128, 135(1) and 135(2), which protect all live animals at the establishment from the time of arrival until death.

The information presented in this document is intended to help CFIA staff undertake their inspections and to be used in conjunction with the following documents:

CFIA must understand Industry requirements to be able to verify compliance to SFCR. Additionally, this document provides guidance intended specifically for inspectors to enable them to conduct compliance verification activities and to take enforcement action.

6.1 Compliance verification

  • Use Compliance Verification System (CVS) Task 5.1.03 – Humane Stunning and Bleeding Activities – to verify that regulatory requirements for humane slaughter are met. Other CVS tasks applicable to stunning and bleeding include:
    • task 5.1.06 – Design of Stunning and Bleeding Areas/Facilities/Equipment
    • task 5.1.12 – Animal Welfare Control Program
  • Rabbits are normally handled and slaughtered in a manner similar to avian species. Use CVS Task 5.1.03 to verify regulatory requirements for humane slaughter and Task 5.1.08 – Stunning and Bleeding Areas/Facilities/Equipment – instead of Task 5.1.06.

6.2 General principles of compliance action applicable to humane slaughter

Please refer to the Food regulatory response guidelines as each situation is unique and different compliance and/or enforcement actions could be taken depending on the context. In the following sub-sections, general examples are given but judgement needs to be applied as well as consultation with the appropriate resources in your Area.

6.2.1 Compliance actions for issues which directly contravene SFCR provisions

  • Issues which directly contravene SFCR are those where the observed deficiency represents non-compliance with a regulatory requirement.
  • Refer to sections 6.2.1.1 and 6.2.1.2 for guidance on zero-tolerance issues and deliberate acts of cruelty.
  • If the operator identifies the issue independently (without being notified by CFIA) and takes immediate and effective corrective action, the process is in control. CFIA takes no action and no Inspector's Report-Corrective Action Request (IR-CAR) is issued.
    • example: the employee sees a bovine returning to sensibility on the bleed line, before or at the same time as CFIA, and immediately re-stuns it
  • If CFIA identifies the issue and the operator takes immediate and effective corrective action upon being made aware of the issue, the process is still not in control because the issue failed to be identified by the operator. CFIA had to take action in this case and alert the operator so that immediate corrective action would be taken. An IR-CAR is issued.
    • example: the employee does not notice a hog returning to sensibility until CFIA draws his attention to it; the employee then immediately re-stuns it
  • If CFIA identifies the issue but the operator either fails to respond, or responds with incorrect action, or the corrective action is not effective, the process is not in control because of deficiencies in development or implementation of the Animal Welfare Preventive Control Plan (AWPCP). CFIA must take control at this point. An IR-CAR is issued.
    • example: the employee does not notice a goat returning to sensibility until CFIA draws his attention to it. The employee then either does nothing at all, or re-sticks it (incorrect action), or tries to re-stun it but the shot fails to render the animal unconscious
  • If the operator identifies the issue but fails to respond or responds incorrectly or ineffectively, the process is not in control. CFIA must take control. An IR-CAR is issued.
    • example: a hog is poorly stunned as it comes out of the automated electric stunner. The sticking employee immediately attempts a re-stun with the back-up captive bolt gun but the bolt does not exteriorize, so he proceeds to stick the hog as it tries to crawl off the bleed table
  • If the operator identifies the issue and takes immediate and effective corrective action each time, but non-compliances to the same section of the SFCR reoccur frequently, this represents a pattern of failure and the process is not in control. This could happen whether or not preventive measures were implemented, in which case they are ineffective. An IR-CAR is issued.
    • the definition of a pattern of failure is subjective. It requires judgement and knowledge of the operator's history of repeat failures
6.2.1.1. Compliance actions for zero tolerance issues
  • Zero-tolerance issues are those where a single occurrence is unacceptable because of the severe animal welfare impact. Zero-tolerance events during mammalian food animal slaughter are animals returning to sensibility on the bleed line and deliberate acts of cruelty. Refer to section 6.2.1.2 for deliberate acts of cruelty (refer to Objective performance criteria for humane slaughter).
  • The operator has full responsibility for monitoring that they remain in compliance with SFCR at all times.
  • The operator's AWPCP must include measures to identify problems and take effective corrective action and preventive measures to prevent reoccurrence.
  • Compliance action depends on the operator's response.
    • an IR-CAR is not issued if the operator identifies the issue independently (without being notified by CFIA) and takes immediate and effective corrective action
      • example: the employee sees a rabbit returning to sensibility on the bleed rail before or at the same time as CFIA and immediately re-stuns it
    • an IR-CAR will be issued either when CFIA identifies the issue and has to request corrective action, or when the operator identifies the issue but either fails to respond; or responds with incorrect action; or the corrective action is not effective
      • example: When you arrive in the stunning area, the floor supervisor tells you hog stunning is not going very well. He calls another employee to re-stun all hogs showing signs of consciousness on the bleed line, and restarts the line without making any stunner adjustments. The problem persists. An IR-CAR is issued
    • an IR-CAR will be issued if a zero tolerance issue is no longer a rare occurrence, even if the operator identifies the issue and responds appropriately
      • example: Hogs are returning to sensibility on the bleed line several times during the day, every day. They are immediately and effectively re-stunned at the first sign of consciousness. The operator has consulted with the manufacturer and adjusted stunner settings according to their recommendations and has increased monitoring, but the issue persists
  • Review the AWPCP to see what it says about zero-tolerance issues, including follow-up procedures to determine the reason for the non-compliant event and effective measures to prevent reoccurrence.
  • Do not confuse zero tolerance issues with self-audit criteria that result in automatic self-audit failure. An automatic self-audit failure because of a failed zero-tolerance criterion does not mean an automatic IR-CAR unless it is a deliberate act of cruelty. IR-CAR issuance depends on who identified the issue and the operator's response to it.
6.2.1.2. Compliance actions for deliberate acts of cruelty
  • Do not confuse zero tolerance issues (e.g. return to sensibility) with deliberate act of cruelty.
  • Deliberate acts of cruelty are those where a single occurrence is unacceptable because of their willful nature and the severe impact on animal welfare.
  • Use judgment to decide whether the action was unintentional or truly deliberate with the clear intention of harming animals.
    • example: the gate at the back of the stunning box falls on the back of an animal and injures it. The intent of the operator must be determined in this case. Did the gate suddenly malfunction and then fall, or did the employee deliberately slam the gate on the animal? Was the gate control mechanism properly maintained, or was this an accident waiting to happen?
  • Deliberate acts of cruelty during slaughter of mammalian food animals could include :
    • intentional hitting or beating an animal with any implement that could cause injury
    • deliberately slamming gates on animals
    • willful misuse of powered equipment or causing injury due to improper maintenance
    • deliberately stunning an animal and allowing it to recover
    • deliberate, multiple applications of a stunner that is obviously malfunctioning
    • deliberately hoisting, shackling, before the animal has been rendered insensible
    • failing to take immediate corrective action if an animal returns to sensibility on the line
    • dressing procedures commenced on an animal with any sign of sensibility or is not dead
  • Compliance and/or enforcement actions (IR-CAR and/or INCR) will automatically be taken by CFIA even if the operator has responded to it because of the intention to harm an animal and the severe impact on animal welfare.
    • example: A bison climbed half-way out of the knock box. An employee ran over and started to beat the animal on the face and over the head with a steel pipe while another employee prodded it in the face with an electric prod to prevent it from climbing all the way out. The supervisor immediately ran over and ordered the employees to stop, and the struggling animal was shot with a firearm
    • example: The operator installed a new Controlled Atmosphere Stunning (CAS) system over the weekend and wishes to test it before start-up of operations. On Sunday evening, the operator runs 20 market hogs through the stunner for a short-duration exposure and lets them recover after they exit the chamber, while evaluating how long it takes for them to regain consciousness. The 18 hogs which recovered from the test stun are returned to their pen for normal slaughter on Monday. You learn about this on Tuesday when an employee confides what happened

6.2.2 Compliance actions for issues which do not directly contravene SFCR provisions

  • CFIA's role is to verify compliance to regulations. When the observation is not a regulatory requirement, and does not result in animal suffering (therefore no violation of SFCR 128 or 135), CFIA conducts the corresponding CVS task and rates the task accordingly.
    • example: You observe that horses are often vocalizing, swaying back and forth and pawing the floor as they stand in the knock box. There is no restraint being applied and the animals are not distressed, struggling or attempting to escape. In this case, CFIA will verify what the AWPCP says about time limits for keeping animals in the knock box and conduct CVS Tasks 5.1.03 and 5.1.06

6.3 Guidelines for verifying compliance to humane slaughter regulatory requirements

  • Observe pre-slaughter restraint, stunning, shackling, hoisting and bleeding activity for a sufficient amount of time to be able to conclude that the process is under control.
  • A consistent, systematic approach is recommended in order to assess all activities in the same manner each time the verification activity is conducted.
  • An efficient approach to verify handling immediately prior to slaughter, stunning effectiveness and bleed rail insensibility is to count a representative amount of animals at each step or over a sufficient amount of time so that effectiveness can be calculated.
    • example: count 50 cattle being stunned and note how many are poorly stunned; multiply the number of poorly stunned cattle by 2 to obtain a percentage and to determine if stunning effectiveness is within expected standards of acceptable performance
    • example: if hog slaughter line speed is 1200 carcasses per hour, observing for 10 minutes will be the equivalent of counting 200 pigs for each criterion assessed; divide the number of pigs not meeting the desired outcome (e.g. hot wanded; poorly stunned) by 2 to obtain a percentage and compare with expected standards of performance)
  • In the above examples, knowledge of actual stunning performance during the verification (refer to Objective performance criteria for humane slaughter) is useful information because it allows CFIA to observe whether industry is taking appropriate corrective action when equipment is functioning below established performance standards.
  • Observe if employees are taking effective control action for ineffective stuns (refer to section 6.8.2), if animals are returning to sensibility on the bleed line, or if there are any hogs reacting when entering the scald tank.
  • Use visual observation to monitor for signs of sensibility, insensibility, or return to sensibility. Avoid touching the animal to test eye reflexes, pain withdrawal reflexes or muscle tone unless you have some doubt about what you are observing. Refer to section 6.7 for more details.

6.4 Restraint for stunning

  • Animals struggling and vocalizing in the restraint system may be an indication that something is wrong (e.g. too much pressure; something causing injury or discomfort; hold-down racks to prevent rearing that press down on the animal's back; slippery floor).
  • Verify that the animal is not restrained for such a long time that it becomes agitated.
  • Verify that the restraint device restrains the animal in a comfortable position.
  • Electro-immobilization must never be used as a form of restraint, for any type of slaughter.

6.5 Stunning

  • The goal of effective stunning is to render the animal unconscious and to have it remain unconscious until it dies from blood loss after bleeding/sticking. To remain in compliance with SFCR 141, the animal must not regain consciousness before death.
  • The sequence of steps after stunning is flexible according to species, stunning method and facility design. After being effectively stunned, the unconscious animal may be shackled, hoisted and then bled, or it may be bled and then shackled and hoisted. The shackle may be applied at any point after stunning, but hoisting must not occur if the animal shows any signs of sensibility.
  • It should never be assumed that a stunning method is 100% irreversible, even if there has been validation (e.g. by the manufacturer or the operator). Indeed, there is always a risk for some animals to be inadequately or lightly stunned in a given lot either because of the equipment and / or the employee; monitoring is therefore always required because zero risk does not exist even when the manufacturer alleges that the equipment and / or the parameters used always result in a stunning which is completely irreversible and is supposed to cause death and/or when the operator alleges that employees are well trained and experienced.

6.5.1 Testing stunning equipment

  • Verify that live animals are never used to test equipment. If the equipment is not immediately and fully capable of producing an effective stun, avoidable suffering will result in non-compliance with SFCR 128 and 135(1) (b).
  • Equipment is available to check electrical and mechanical stunners.
    • resistors can be used to measure current flow in electrical stunners
    • a velocity checker is the only acceptable method to validate captive bolt stunner effectiveness
      • frequency of captive bolt velocity checks will be outcome-based
      • a velocity check is mandatory if there is any doubt about stunning effectiveness that is not linked to employee performance (training, knowledge, physical ability) and/or animal restraint issues, but is linked to equipment performance itself
      • frequency also depends on how extensively a particular stunner is used (for example, a back-up device used only a few times daily vs. a primary stunner used 100 times a day)
  • CAS systems should be validated based on research data using gas concentrations and exposure times that are known to consistently produce an effective stun on the same age, size and species.
    • Monitoring must occur at start up, after breaks in production and for a group of hogs differing in size or age from previous groups, for example, from different producers. More frequent monitoring may be required if there are problems with induction.
    • Even with parameters known to be effective, animals must be monitored closely every time any change to the gas mix or concentration is made

6.5.2 Mechanical stunning

  • Effective stunning involves destruction of the vital centres (for breathing, for the circulatory system and for consciousness) located in the brainstem structures (pons and medulla).
  • Refer to Annex 1 – Brain and brainstem anatomy and Neurological Basis of Effective Stunning – for further information on the anatomy and function of the brainstem structures.
6.5.2.1 Penetrating captive bolt stunning
  • Approaches other than frontal midline (e.g. top or side of the head) may be aimed too far back and sever the spinal cord instead of destroying the pons and medulla, resulting in a paralyzed yet conscious animal.
  • Physical damage to the brain from a captive bolt is less extensive than from a bullet. Unusual or inconsistent indicators of consciousness may be observed with incomplete damage to one or more of the vital centres if the captive bolt is slightly off-target.
  • If a second captive bolt stun is required, the second shot should avoid the same spot as the first shot because immediate swelling around the wound will absorb the impact of the second shot and make it less effective. The second shot should then be above (higher) and to one side of the first shot and as close to the correct position as possible.
  • An effective captive bolt stun will cause immediate collapse with an initial tonic phase where the body will be stiff, followed by a clonic phase where the body relaxes and vigorous uncoordinated kicking or paddling leg movements may occur. The eyes will remain wide open and will have no movement; the head will be completely dead.
6.5.2.1.1 Penetrative captive bolt euthanasia
  • Captive bolt stunners are often the method of choice for euthanizing mammalian food animals that will not be processed for food (e.g. animals that are euthanized by the operator or those condemned on ante-mortem inspection), although other euthanasia methods can be used (firearm; gas for pigs or poultry).
  • Since the stun is considered reversible, verify that the operator is taking measures to ensure animals are killed. These measures include either
    • applying a secondary kill method and confirming death, or
    • remaining with the animal until there are demonstrable signs of death
  • Signs of death are:
    • no breathing
    • no corneal reflex
    • no anal tone
    • cyanotic mucous membranes
  • Secondary kill methods applied to unconscious animals include:
    • intra-thoracic bleeding (chest sticking) to cause internal exsanguination
    • neck sticking to cause external exsanguination
    • pithing
      • pithing can only be performed on animals that are not destined for human consumption
      • pithing of bovines over the age of thirty months (OTM) is prohibited unless controls are in place to ensure the entire carcass is treated as specified risk material (SRM)
    • second application of the captive bolt stunner
      • Some operators do this to avoid exsanguination. A second shot does not ensure death will occur, so it is not considered a secondary kill method. Death must still be confirmed
6.5.2.2 Non-penetrating captive bolt stunning
  • Non-penetrative concussive stunning is not recommended for bovines because it requires much more accuracy and does not work well for thicker skulls of bulls and older cows, or long/thick hair on the forehead. It is better suited to very young bovines and small ruminants, with excellent head restraint.
  • If an operator wishes to use non-penetrating concussive devices to stun cattle, they must demonstrate that they can consistently stun (refer to the Objective performance criteria for humane slaughter) with a single shot, such that the animal is immediately rendered fully unconscious, and that it does not regain consciousness before death. 
  • Non-penetrating captive bolt stunners are often used immediately after the cut during ritual slaughter. For post-cut stunning after ritual slaughter, SFCR 141 is exempted (SFCR 144 applies) but the stun must still be effective at immediately rendering the animal unconscious and not creating avoidable suffering.
6.5.2.3 Firearm stunning
  • Firearms cause severe destruction in the brain and are therefore more forgiving in terms of accuracy, but it is possible to miss the brainstem target and have a poor stun or a reversible stun.
  • Firearm stunning may be the best option for horses, adult bison, water buffalo, large bulls and mature sows and boars when penetrative captive bolt stunning fails to consistently be effective.
    • although penetrative captive bolt stunners can have longer, heavier bolts and sufficient power and velocity to stun very large animals or those with thick frontal bones, the chance of failure in these animals is increased compared to when high-caliber firearms are used
    • horses are head-shy and require a very high stunning approach, which makes effective captive bolt stunning very difficult
  • An effective firearm stun will result in immediate collapse and generally no further movement, although uncoordinated leg movements may occur. The eyes will be open with a blank stare and the head will be completely dead.
6.5.2.4 Security knocks
  • The concept of security knocks is only applicable to mechanical stunning and is a preventive measure.
  • A security knock is a second stun applied to an already unconscious animal. This is acceptable as long as the first stun has been effective. On the other hand, if the first stun has not been fully effective, the second is a re-stun and is a correction procedure and not a security knock.
  • A security knock is delivered to:
    • ensure the animal is well stunned
    • ensure it remains unconscious until it is dead
    • ensure a good stun when the stunning employee has a feeling that the first blow was not precisely applied and the brainstem target was not reached perfectly, but the animal appears unconscious
    • reduce excessive clonic convulsions (for personnel workplace safety)
    • give peace of mind
  • The stunning employee occasionally or routinely give security knocks following penetrating captive bolt stunning of horses and of larger or older animals which will have thicker craniums.
  • The use of security knocks must be described in the AWPCP.
  • A security knock must not be used to compensate for defective or inadequate stunning equipment (e.g. a captive bolt stunner designed for smaller or younger animals).
  • Security knocks may be used in case of a short unexpected delay as a preventive measure, e.g. hoisting preparation.
    • it is not acceptable to use security knocks in situations where bleeding is routinely delayed due to operational factors (e.g. weighing the animal before bleeding) or facility design. In these situations, a well-stunned animal may return to sensibility before it is bled out and corrective measures are required as well as the factors delaying bleeding need to be addressed
  • It should never be necessary to deliver more than one security knock. A second or third security knock means the first security knock was not effective, either because it missed the target or because equipment is defective, inadequate or poorly maintained.
    • verify that the first stun was effective at immediately rendering the animal unconscious
    • discuss your concerns about multiple security knocks on a given animal with the operator

6.5.3 Electrical stunning

  • Electrical stunning is most frequently used in pigs, small ruminants and rabbits, but it can be used in bovine slaughter too.
  • Electrocution refers to killing an animal, by causing a cardiac arrest, with an electric current.
  • Electro-narcosis refers to stunning an animal with an electric current. In this case, brain function is temporarily disrupted, and the animal will recover if it is not bled out rapidly.
6.5.3.1 Head to body electrical stunning
  • Head to body stunning causes immediate unconsciousness when current flows through the brain, and causes cardiac arrest when current simultaneously or subsequently flows through the heart.
  • Head to body stunning is theoretically irreversible. It should be considered potentially reversible because current of insufficient duration or strength may not trigger ventricular fibrillation and cardiac arrest. Monitoring is required to ensure animals do not return to sensibility.
  • There are different methods of achieving a head to body electrical stun, using either automated equipment or hand-held equipment.
  • Electrical current must be applied to the heart either at the same time as the head stun or in a second phase following the head stun. It must never be applied to the heart prior to the head stun because this causes pain.
  • Verify proper electrode placement. Refer to Annex A – Guidelines for stunning techniques of mammalian food animals for landmarks.
  • An electrocuted animal will become rigid with slight body tremors, and will then gradually relax with no further movement.
  • Clonic paddling of the legs may occur, and this is an indication the animal did not go into cardiac arrest (and will wake up if it is not bled rapidly).
  • It is possible to have cardiac arrest without an effective stun. The animal will soon die, but it will be sensible until it does. Verify that there are no signs of sensibility and that the animal is immediately re-stunned if such signs are present.
6.5.3.2 Head-only electrical stunning
  • Verify that the electrodes are placed correctly to span the brain so that an imaginary line drawn between the two electrodes goes right through the brain.
  • Acceptable stunning approaches are described in Annex A – Guidelines for stunning techniques of mammalian food animals.
  • Unacceptable positions for head-only stunning include:
    • on only one side of the head
    • top to bottom position over and under the muzzle
    • across the neck
    • in any position where an imaginary line drawn between the two electrodes does not go through the brain
  • A head-only stun will not cause cardiac arrest and will be of shorter duration than a head to body stun. Verify that bleeding occurs preferably within 10 to 15 seconds of the end of stun application, and that animals are not returning to sensibility before dying of blood loss.
  • Head-only stunning of mammalian food animals will result in a grand mal epileptic seizure with two phases:
    • tonic phase occurs first, where the animal is rigid, often with a raised head and arched back, front limbs extended rigidly and hind limbs flexed under the body, and eyes tightly shut
    • clonic phase occurs next, where the body relaxes and vigorous uncoordinated kicking or paddling occurs. The eyeballs will move downward and there may be urination or defecation. Eventually the eyes relax into a blank stare
  • If the animal is not bled, it will return to sensibility after the kicking stops. During this recovery phase, normal rhythmic breathing will resume and there will be response to painful stimuli.
  • If these phases are not obviously present, the stun is poor or ineffective. The animal must be re-stunned.
6.5.3.3 Hot wanding and electrode placement error
  • Verify that pigs are not squealing as stun application begins, or during stun application.
  • Hot wanding occurs when the stunning electrode is energized before it is fully pressed against the animal's body, thus giving it a strong shock. It also occurs when operator breaks and re-makes the circuit during the stun, or if the cardiac stun occurs before the head stun.
  • Verify that the operator takes immediate corrective action to address improper electric stun application if the incidence of hot wanding exceeds acceptable performance standards as per Objective performance criteria for humane slaughter.
  • Improper stunning electrode placement, where electrodes do not span the brain, is likely to result in an ineffective stun or in electro-immobilization.
  • Verify that the operator takes immediate corrective action to address improper stunning electrode placement if placement error exceeds 1%. Refer to Objective performance criteria for humane slaughter.
6.5.3.4 Double stuns for electric stunning
  • With electrical stunning, a routine second application of reduced electric current to control clonic convulsions for shackling ease is not the same as a security knock. The effect of the second electric current is to induce immobilization and therefore stop clonic kicking.
  • Because it masks clonic convulsions, it is not possible to determine if the first stun was effective or not.
  • The immobilizing current also masks signs of return to sensibility.
  • An operator wishing to apply a second electric stun must demonstrate that the first stun is effective.

6.5.4 Controlled atmosphere stunning

  • Verify that the gondolas (elevator boxes) holding groups of pigs are not overcrowded. This means that pigs must have sufficient room to stand comfortably on their feet without being on top of each other. As a guideline, no more than 4% of the gondolas should be overcrowded. If the percentage of overcrowded gondolas exceeds 4%, the operator must take corrective action to reduce the number of pigs per gondola to an acceptable level. Refer to Objective performance criteria for humane slaughter.
  • Observe stunning especially during the induction phase, from the point of first exposure to gas until they lose consciousness. This is the time where adverse behaviour could occur.
  • During the induction phase, visually observe that pigs are not adversely reacting to gas exposure. They should not be panicking, climbing on top of each other, vocalizing or actively attempting to escape.
  • Be aware that mild aversive behaviour may occur before pigs collapse, even with acceptable gas mixtures and gas concentrations. This is due to:
    • the nature of the gas (carbon dioxide is irritating to respiratory mucous membranes)
    • hog genetics (some are more excitable and show more aversive behaviour) and
    • pre-slaughter handling (pigs that are excited, subjected to electric prod use or handled roughly will take longer to become unconscious and will struggle more upon gas exposure)
  • The ability to monitor animals at all times means that someone can observe induction at any time they wish to do so. It does not mean that the operator must constantly monitor induction.
  • Monitoring must occur at start up, after breaks in production and for a group of hogs differing in size or age from previous groups, for example, from different producers. More frequent monitoring may be required if there are problems with induction.
  • Even with parameters known to be effective, animals must be monitored closely every time any change to the gas mix or concentration is made.
  • An effective gas stun will result in a completely limp, floppy carcass, although slow limb movements may occur. Agonal breathing and nystagmus may also be observed.
  • For plants with shorter gas exposure times, there is a risk animals may not be fully unconscious when they emerge from the CO2 chamber, or that they return to sensibility before being shackled and hoisted.
    • verify that all pigs are unconscious from the point of stunner exit
    • verify that the operator is monitoring sensibility/insensibility while animals are still on the shackle table, and not just on the bleed rail
  • It is not acceptable to have sticking located so far from the gas stunner that the pigs require or are given a second stun prior to sticking.
  • CAS may be used for euthanasia. Gas concentrations and exposure times usually need to be greater than for stunning, and they must be verified for effectiveness. Death must always be confirmed. Refer to section 6.5.2.1.1 for signs confirming death.

6.5.5 Ritual slaughter with prior stunning

  • If an operator wishes to stun animals prior to ritual slaughter, the requirements of SFCR 141 fully apply; the stun has to be effective; monitoring must ensure stunning is effective; and corrective action must be taken if it is not effective.
  • Light stunning or electro-immobilization, as a means to immobilize the animal prior to the ritual cut, is not acceptable. The operator can adjust stunner settings to ensure animals are not killed by voltage/current/frequency combinations known to cause electrocution and cardiac arrest, but the electrical current flowing through each animal must be strong enough to stun effectively (electro-narcosis) and to keep the animal unconscious until it has died from blood loss.

6.6 Bleeding

  • Prompt and effective bleed-out is important to ensure the requirements of SFCR 141are met and the animal dies before it can regain consciousness.
  • Verify that the animal is unconscious before it is bled, and that it does not regain sensibility on the bleed rail.

6.6.1 Stun-to-stick interval

  • Stun-to-stick intervals are not specified for penetrating captive bolt stunning, firearm stunning and gas stunning with long duration immersion because these stunning methods are generally assumed to be irreversible, although this is not always the case.
  • Return to sensibility can occur in animals stunned by any method if bleeding is delayed.
  • Best practice is to stick as soon as possible after stunning.

6.7 Monitoring sensibility, insensibility and return to sensibility

  • Refer to the "Table of signs for monitoring the outcome of stunning in mammalian food animals" in Mechanical, electrical, gas stunning, slaughter methods and monitoring signs of unconsciousness or consciousness for a complete list of signs of unconsciousness and consciousness (or return to consciousness) in mammalian food animals following electrical, captive bolt and gas stunning.
  • Refer to Annex 2 – Signs of a properly stunned animal by stunning method for a summary of indicators for cattle, pigs and sheep with captive bolt, electrical and gas stunning.
  • Note that the terms "consciousness" and "sensibility" are interchangeable and mean the same thing. Likewise, "unconsciousness" and "insensibility" are equivalent terms.
  • Always evaluate signs of return to sensibility collectively (as a whole), instead of focussing attention on a single sign.
  • By itself, a single sign (e.g. corneal reflex; twitching of the nares; lip movement; reaction to a pin or needle prick on the snout) may not necessarily indicate that an animal is sensible.
    • 3 things can happen when you see a single sign of sensibility:
      • the sign may disappear and never reappear: the animal is unconscious
      • the sign can persist: questionable insensibility; corrective action required
      • the sign can persist and then be followed by one or more other signs of sensibility: the animal is returning to sensibility; immediate corrective action required to re-stun or kill the animal
  • Immediate corrective action must be taken if there is any doubt the animal is returning to sensibility no matter where, either on the shackling table or on the bleeding rail.

6.7.1 Interpretation of specific signs

  • Eye reflexes (corneal, palpebral):
    • eye reflexes indicate that an animal is alive but they do not necessarily mean the animal is conscious, especially when there are no other signs of sensibility
    • research has determined that an animal with a weak corneal reflex is unconscious if no other indicators of consciousness are present
    • a weak corneal reflex may occur in animals properly stunned by electricity or gas because the brainstem is intact
    • the presence of a weak corneal is one of the first signs of potential return to sensibility, so continuous observation is necessary to determine if the reflex becomes stronger or is followed by another sign (e.g. rhythmic breathing) In these cases, the animal must be immediately re-stunned
    • brainstem reflexes are not consistently reliable indicators of insensibility or return to sensibility for stunning methods that leave the brainstem intact. They should not be used routinely because of variability and inconsistent interpretation 
    • however if there is any doubt that natural blinking or other signs of sensibility may have been observed, eliciting eye reflexes is justified 
    • wait a few seconds before attempting to elicit corneal or palpebral reflexes in electrically stunned animals because the epileptiform seizure masks eye reflexes and makes them hard to interpret. It is not recommended to routinely test eye reflexes in electrically-stunned animals
    • the corneal reflex must be absent before dressing procedures begin, regardless of stunning method
    • do not confuse palpebral reflexes with muscular fasciculation of the eyelids following electrical stunning. These muscle movements are normal
    • do not confuse eye reflexes with spontaneous blinking. An animal with spontaneous / natural blinking is sensible
    • test eye reflexes sparingly because they require close contact with the animal. Rely instead on visual observation from a distance of eye movements and other indicators of consciousness/unconsciousness. If you see an animal with questionable signs, testing eye reflexes may provide valuable information at this time
  • Eye movements:
    • the following eye movements are all indicators of sensibility:
      • spontaneous (natural) blinking without touching the eye
      • blinking following a threat reflex, where a hand is waved in front of the eyes but does not touch any part of the eye or eyelashes
      • tracking movements, where the animal's eyes focus on and follow movement of persons, objects, etc.
    • all eye movements, including nystagmus or any rotation, must be absent in mechanically stunned animals. If this is not the case, the animal must be re-stunned
  • Nystagmus (vibrating eye):
    • nystagmus may occur following electrical or gas stunning. It must always be absent after mechanical stunning
    • nystagmus is usually associated with higher electrical stunning frequencies or shorter gas exposures. Nystagmus following gas stunning should be an infrequent observation
    • the presence of nystagmus in mechanically stunned animal is an indicator of return to sensibility
  • Tongue, lip and muzzle movements:
    • the tongue should hang out and be straight and limp, with no muscle tone
    • a tongue moving in and out, or a curled, stiff tongue, are indicators of partial sensibility or return to sensibility
    • the tongue may not hang out in all unconscious animals. It may be trapped in the mouth
    • twitching lips, nares or muzzle are a sign of potential return to sensibility in mechanically stunned animals. These signs are more difficult to interpret in electrically-stunned animals, especially during the tonic phase
  • Vocalization:
    • any vocalization (squeal, bellow, moo etc.) is an indicator of sensibility
  • Rhythmic breathing:
    • rhythmic breathing occurs when the ribcage moves in and out following a regular rhythm (inspiration-expiration) and at least two times in a row. It is on the edge between the transition phase and consciousness
    • presence of rhythmic breathing indicates that the animal is either returning to sensibility, or is already sensible
    • return of rhythmic breathing in an animal regaining consciousness may begin as regular gagging
  • Agonal breathing:
    • agonal breathing may occur normally following effective electrical or gas stunning because the respiratory center of the brainstem is intact. It must always be absent after mechanical stunning
    • agonal breathing is not a sign of actual or potential return to sensibility. It does not indicate the animal might be waking up.  Agonal breathing during electric or gas stunning indicates the animal is dying
    • agonal breathing does not have any regular rhythm, no in and out movement of the rib cage and no tongue muscle tone
    • it may appear as a single or repeated open mouth inspiratory gasp, like a fish out of water
    • the mouth may open wide, and the head may arch ventrally during an agonal gasp if the animal is hoisted
    • do not confuse agonal breathing with rhythmic breathing or gasping attempts to breathe
  • Response to a painful stimulus:
    • test pain response either by pinching the nose or pricking the nose or snout with a pin or needle
    • wait until the tonic phase is over before testing pain response in electrically-stunned animals
    • a single or weak pain response may not necessarily indicate sensibility if it is the only sign observed. Look for other signs as well
  • Leg movements:
    • uncoordinated, spastic leg movements are normal in unconscious animals following effective mechanical and electrical stunning
    • the hind limbs will have kicking movements, while the front limbs will have paddling movements
    • slow paddling leg movements may be seen following effective gas stunning
    • leg movements may persist for a long time in unconscious animals
  • Righting reflex:
    • a conscious animal will try to regain its upright posture, even when hanging by one leg on the shackle line, by raising its head and arching its back
    • the head is not always raised. In some cases it can be flexed toward the abdomen or turned sideways
    • the animal with a righting reflex will have muscle tone. The head and neck will be stiff and will not be limp
  • Head:
    • an unconscious animal will have a floppy, limp head (like a rag doll) with absolutely no muscle tone

6.7.2 Progression of signs during return to sensibility

  • When an animal returns to sensibility, the progression from full insensibility to full sensibility occurs gradually in a continuum of events. An animal does not automatically go from unconscious to sensible.
  • The transition zone between unconsciousness and consciousness can be confusing and difficult to interpret as signs gradually begin to appear, possibly weakly or intermittently at first, possibly one or more at a time.
  • An animal can progress from fully unconscious to fully conscious in as little as 15 to 20 seconds. Therefore it is important not to hesitate too long when trying to interpret indicators and decide if they are significant or not.
  • An animal that is fully unconscious (insensible) has none of these 3 indicators:
    • corneal reflex
    • palpebral reflex
    • rhythmic breathing
  • An animal that is beginning to transition back to consciousness has 1 or more of these indicators:
    • corneal reflex
    • palpebral reflex
    • rhythmic breathing

An animal that is beginning to transition back to consciousness must be re-stunned before the next indicators of sensibility appear

  • An animal that is conscious has 1 or more of these indicators:
    • spontaneous natural blinking
    • menace (threat) reflex (wave hand near eye)
    • eye tracking movements
    • response to a painful stimulus
    • righting reflex and attempt to raise the head
    • voluntary vocalization
    • standing or sternal posture

A conscious animal conscious must immediately be re-stunned

6.8 Corrective actions for failed stuns and animals returning to sensibility

6.8.1 Understanding what an objective performance of 96% or 98% efficiency means

  • We do not expect stunning employee and automated stunning equipment to be 100% effective at all times (refer to the Objective performance criteria for humane slaughter).
    • employees performing mechanical stunning do become fatigued after a while or experience occasional difficulty with certain animals
    • automated equipment removes the human error element, but failure can occur due to individual animal electrical resistance and positioning
  • We expect that trained and skilled employees performing mechanical stunning with well-maintained equipment should be able to effectively stun animals with a single shot at least 96% of the time. If not, corrective action is required to improve stunning efficiency, either by rotating employees replacing the equipment or cleaning/maintaining the equipment properly.
  • We also expect automated electrical and gas stunning equipment to be at least 98% effective at all times. If it is not, corrective action on the equipment must be taken to increase stunning or bleeding efficiency.
  • This does not mean there is any tolerance for poorly stunned animals. Corrective action must be taken for every single improperly stunned animal regardless of equipment performance. "Tolerance" is for the employee/equipment performance itself. We will tolerate up to 2% failed electrical/gas stuns or up to 4% failed mechanical stuns without taking corrective action on the employee/equipment, but corrective action will always be taken on each animal that is improperly stunned.

6.8.2 Expected corrective

  • For failed stuns, immediate re-stunning is required, either with the same stunning device or with a back-up stunning device:
    • electric stunning: re-stun with hand-held electric stunning device or with captive bolt stunner
    • gas stunning: re-stun with captive bolt stunner
    • captive bolt stunning: re-stun with captive bolt stunner or firearm
    • firearm: re-stun with captive bolt stunner or firearm
  • For ineffective bleed-out (poor sticking):
    • re-stick if animal is unconscious
    • re-stun first, and then re-stick if animal is showing signs of return to sensibility
  • For animals returning to sensibility on the bleed rail:
    • immediate re-stunning
    • immediate follow-up to evaluate stunning effectiveness

6.9 Rabbits

  • Water bath electric stunning is not allowed because SFCR 143 prohibits shackling conscious rabbits.
  • For head-only electric stunning, the electrodes must never be applied on the neck or in any position that does not span the brain.
  • Captive bolt stunning may be performed while rabbits are still in their crates.
  • Bleeding time must not be less than 90 seconds to permit complete bleeding (IG under development).

7.0 Annexes

Annex 1: Brain and brainstem anatomy and Neurological Basis of Effective Stunning

Description follows
Figure 1: Target trajectory of the projectile in a horse brain to ensure effective stunning (median section)

Source: Konïg HE, Liebich H-G et al. Veterinary Anatomy of Domestic Mammals - Textbook and Colour Atlas, 2009, 4e edition

Although this is a picture of a horse's brain, the control centres are located essentially in the same place for all species. The brainstem is common to all mammals. The actual pathway of the trajectory may be variable, depending on how the animal's head is held when shot; however, the ultimate destination, mid-brain and brainstem, is what is most important.

Neuroanatomy:

The central nervous system (CNS) consists of the spinal cord and the brain.

The brain in very general terms is divided into the following;

  1. Brainstem
    • (1) medulla oblongata
    • (2) pons
    • (3) cerebellum
  2. Midbrain
  3. Forebrain
    • (1) cerebral hemispheres
    • (2) basal nuclei

Medulla oblongata

Contains the;

  1. Respiratory Centre - autonomic control of respiration
  2. Circulatory Centre - autonomic control of heart rate and blood pressure
  3. Reticular Formation (medulla oblongata portion of the Ascending Reticular Activation Centre)
  4. Nuclei for cranial nerves VI to XII

Pons

Contains the;

  1. Reticular Activation Centre (pons section of ARAS)
  2. Nuclei or centres for controlling motor functions of the body
  3. Nuclei for cranial nerve V

Midbrain

Contains the;

  1. Reticular Formation (midbrain section of the ARAS)
  2. Nuclei for cranial nerves III and IV

Forebrain

Contains many centres some of which are associated with respiration, circulation and consciousness, but none of which are as critical to life as those found in the brainstem and midbrain.

Neurology:

Medulla oblongata

Function;

  1. Respiratory Centre - autonomic control of respiration
  2. Circulatory Centre - autonomic control of heart rate and blood pressure
  3. Reticular Formation (medulla oblongata portion of the Ascending Reticular Activation Centre) – plays a role in consciousness in animals and humans
  4. Cranial nerves provide input to the ASAR

Pons

Function;

  1. Reticular Activation Centre (pons section of ARAS) - the KEY centre in the brain for consciousness in animals and humans
  2. Cranial nerve provide input to the ASAR

Midbrain

Function;

  1. Reticular Formation (midbrain section of the ARAS) - a role in consciousness in animals and humans
  2. Cranial nerves provide input to the ASAR

Forebrain

Note: a single focal forebrain lesion alone does not produce coma (complete loss of consciousness). There must be significant damage to the brainstem to induce coma.

Respiration

  • Control centre found in the medulla oblongata
  • Trauma to the brainstem (medulla oblongata) damages the respiratory control centre and/or blocks respiratory centre pathways resulting in the cessation of respiration.

Circulation

  • Control centre for circulatory system found in the medulla oblongata
  • Extensive trauma reduces ability to maintain effective heart rate and blood pressure

Consciousness

  • Consciousness is maintained by sensory stimuli that act through the ascending reticular activation system (ARAS)
  • All sensory pathways forward information to the reticular formation of the pons and midbrain
  • The pons is the KEY component of the ARAS for consciousness in animals and humans
  • R.A.S. of the brainstem (medulla and especially the pons) forwards this information to the midbrain and then the cerebral hemispheres.
  • The cerebral hemispheres play a role in consciousness; however, their role in the process is predicated on their having received sensory input from the lower levels of the ARAS, especially input from the pons
  • The deepest comas are related to brainstem (pons) injury

Types of Trauma to the Brainstem and Midbrain

Note: Sensory tracts are located lateral in the brainstem, midbrain and spinal cord, motor tracts are medial.

  1. Bilateral destructive lesion of the rostral pons results in
    • (1) greatest extensor rigidity,
    • (2) deepest coma or brainstem death,
    • (3) pupils dilated and
    • (4) eyes unmoving
  2. Bilateral destruction of the medulla results in respiratory arrest
  3. Unilateral damage to medulla, pons or midbrain may result in short lived or incomplete cessation of responses

Brain dead (Kumar et al)

Coma and apneic humans that lack all brainstem reflexes have;

  1. Irreversible loss of consciousness
  2. Spontaneous respiration absent - loss of capacity to breath
  3. Oculocephalic reflexes absent (eyes fixed centre)
  4. Pupils dilated, fixed and unresponsive to light
  5. Corneal reflexes absent

Summary:

  1. Bilateral damage to the reticular formation of the pons causes the deepest forms of unconsciousness.
  2. Unilateral lesions in the brainstem can be associated with short lapses of consciousness or incomplete unconsciousness.
  3. The human upper pons (analogous to the rostral pons in animals) plays a crucial role in the maintenance of consciousness compared with the midbrain segment of the ARAS.
  4. Bilateral lesions to the medulla oblongata result in respiratory and circulatory failure.
  5. The most effective approach for an effective stun is a midline frontal approach where the stunning projectile is directed towards the midbrain, pons and medulla oblongata. Directing the stunning device at other targets (e.g.: the side of the head, behind the ear or near the poll at the top or the back of the head) increase the likelihood that crucial control centres (for consciousness, respiration and the circulatory system) in the brainstem and midbrain will be missed. A projectile directed at the poll can sever the spinal cord without causing unconsciousness.

References

  1. Konïg HE, Liebich H-G, et al. Veterinary Anatomy of Domestic Mammals - Textbook and Colour Atlas, 2009, 4th Edition.
  2. Dyce KM, Sack WO et al. Textbook of Veterinary Anatomy, 2002, 3rd Edition.
  3. Sisson S, Grossman JD, et al. The Anatomy of Domestic Animals, 1953, 4th Edition.
  4. Mayhew IGJ, et al. Large Animal Neurology, 2009, 2nd Edition.
  5. Oliver JE, Lorenz MD, et al. Handbook of Veterinary Neurology, 1998, 3rd Edition.
  6. Kumar P, Clark M et al. Clinical Medicine, 2005, 6th Edition.
  7. Parvizi J, Damasio AR et al. Neuroanatomical correlates of brainstem coma. Brain, A Journal of Neurology, Oxford (2003), 126, 1524-1536.

Annex 2 : Signs of a properly stunned animal by stunning method

Signs of a Properly Stunned Animal by Stunning Method
Head Tongue Back Eyes Limbs Vocalization Respiration Tail Response to Pain
Cattle
Captive
Bolt		 Must appear dead, hang straight and floppy Straight and limp Hanging straight, no righting reflex No natural blinking; wide open, blank stare, no response to touch; nystagmus absent Uncoordinated kicking of hind legs acceptable, no righting reflex present None Rhythmic breathing (ribs moving in and out at least twice) is absent.
Agonal gasping not acceptable		 Relaxes shortly after being on the rail A pinch or pinprick may be applied to nose only and no response should be observed
Cattle
Electric		 Must appear dead, hang straight and floppy Straight and limp Hanging straight, no righting reflex No natural blinking;
Eyes may vibrate (Nystagmus), 		Uncoordinated kicking of hind legs acceptable, no righting reflex present None Rhythmic breathing (ribs moving in and out at least twice) is absent;
Agonal gasping like a fish out of water normal; 		Relaxes shortly after being on the rail A pinch or pinprick may be applied to nose only and no response should be observed
Pigs
CO2		 Must appear dead, hang straight and floppy Straight and limp Hanging straight, no righting reflex No natural blinking Uncoordinated kicking of hind legs acceptable, no righting reflex present None Rhythmic breathing (ribs moving in and out at least twice) is absent;
Agonal gasping like a fish out of water normal		 Relaxes shortly after being on the rail A pinch or pinprick may be applied to nose only and no response should be observed
Pigs
Electric		 Must appear dead, hang straight and floppy Straight and limp Hanging straight, no righting reflex No natural blinking;
Eyes may vibrate (Nystagmus) 		Uncoordinated kicking of hind legs acceptable, no righting reflex present None Rhythmic breathing (ribs moving in and out at least twice) is absent;
Agonal gasping like a fish out of water normal; 		Relaxes shortly after being on the rail A pinch or pinprick may be applied to nose only and no response should be observed
Pigs
Captive
Bolt		 Must appear dead, hang straight and floppy Straight and limp Hanging straight, no righting reflex No natural blinking; Wide open, blank stare; no response to touch; nystagmus absent Uncoordinated kicking of hind legs acceptable, no righting reflex present None Rhythmic breathing (ribs moving in and out at least twice) is absent;
Agonal gasping not acceptable		 Relaxes shortly after being on the rail A pinch or pinprick may be applied to nose only and no response should be observed
Sheep
Electric		 Must appear dead; neck hangs on an angle with limp and floppy head Straight and limp Due to anatomical differences in sheep, back may not hang completely straight;
no righting reflex		 Eyes may vibrate (Nystagmus), but no natural blinking Uncoordinated kicking of hind legs acceptable, no righting reflex present None Rhythmic breathing (ribs moving in and out at least twice) is ABSENT
Agonal gasping like a fish out of water normal; 		Relaxes shortly after being on the rail A pinch or pinprick may be applied to nose only and no response should be observed

Source: Temple Grandin: June 2017 Recommended Animal Handling Guidelines & Audit Guide, NAMI (North American Meat Institute)

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