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Guidelines for Stunning Techniques of Mammalian Food Animals
1. Cattle

1.1 Mechanical

Important factors:

  • Handling and restraint facilities should be appropriate to avoid movement of cattle during stunning.
  • Cattle, especially mature males with horns, have very thick frontal bones overlaying the brain.
  • Plan the trajectory so that the bolt or projectile travels through the brain (cerebral hemispheres, midbrain, brainstem). The most significant of these are the midbrain and brainstem, which are at the level of the bottom of the attachment of the ears.

Note: Together the midbrain and brainstem are responsible for eye movement and body movement, the level of consciousness and maintaining vital body functions, such as breathing and heart rate. (The cerebral hemispheres are associated with higher brain functions.)

The trajectory is especially important when a firearm is used and the shooter may need to be on steps or an elevation to achieve the proper angle. Be aware that the trajectory of the projectile must pass through the midbrain and brainstem (angle is very important). (See [b] below.)

1.1.1 Landmarks and approaches

1.1.1.1 Perpendicular to the front of the head approach

Penetrative Captive Bolt

The intersection of diagonal lines from the middle of the attachment of each horn, or the nuchal crest (the ridge at the back of skull where the neck muscles attach to the head) to the eyes, depending on cattle breed and head shape. The muzzle of the gun should be perpendicular to the front of the skull surface to direct the bolt through the upper brain towards the brainstem. (See [a] and [b] below.)

This is the approach used with captive bolt stunning devices (pneumatic and cartridge fired). This approach is sometimes used with firearms. (See pictures [a] and [b] below.)

Perpendicular to the Front of the Head Approach
[a] Frontal View
Perpendicular to the Front of the Head Approach - Frontal View
HSA
Frontal view of bovine head with landmarks.

foramen magnum
brainstem
and midbrain
[in the centre
of the skull]

[b] Side View
Perpendicular to the Front of the Head Approach - Side View
Legend - Perpendicular to the Front of the Head Approach
Image Description
Landmark and angle relative to the front of the skull when cattle are stunned with either a penetrating captive bolt stunning device or firearm Landmark and angle relative to the front of the skull when cattle are stunned with either a penetrating captive bolt stunning device or firearm. They are discharged perpendicular to the front of the head.
Location of the foramen magnum, brainstem and midbrain in centre of the skull Location of the foramen magnum, brainstem and midbrain in centre of the skull.
Intersection of the diagonal lines indicates the entry point for the bolt or projectile of a mechanical stunning device held perpendicular to the front of the skull Intersection of the diagonal lines indicates the entry point for the bolt or projectile of a mechanical stunning device held perpendicular to the front of the skull.
Non-penetrative Captive bolt

This method requires an extremely accurate aim. As the amount of damage to the skull is reduced, placement of the shot must become precise to achieve instantaneous insensibility. Observations indicate that non-penetrating stunners may be less effective on cattle with woolly heads such as Herefords compared to short haired cattle.

The position of the non-penetrative captive bolt pistol is approximately 20 mm above the position used for the penetrative captive bolt. The animal must be bleed within 30 seconds. The muzzle of the gun must be perpendicular to the front of the skull surface to direct the impact of the blow through the upper brain towards the brainstem.

HSA
Frontal view of bovine head with landmarks for non-penetrative captive bolt that is approximately 20 mm above the intersection of an X formed by diagonal lines from the eyes to the base of the horns.

1.1.1.2 Firearm discharged with the operator standing at ground level in front of the animal

When an animal is stunned with the operator standing at ground level in front of the animal, the entry point of the projectile into the front of the head (skull) must be much lower than what is used with the perpendicular approach, if it is to penetrate the midbrain and brainstem. (See pictures [a] and [b] below.)

In general, it is recommended that the employee to be on steps or an elevation so the firearm shooting can be done perpendicularly to the skull to achieve a better angle more readily. When done this way, the targeted areas will be the same as for captive bolt except for the poll shot which should be used for firearms only (the firearm is the most reliable method to destroy the brainstem from this angle). This angle is for animals with thick skull mass, horns or the frontal shot is difficult to make.

The midbrain and brainstem are the central and lower portions of the brain. They are located in the central and lower portion of the cranial vault [space containing the brain]. (See [a] and [b] below.)

Ground Level Approach
[a] Side View
cow with firearm and projectile aimed at the midbrain and brainstem

[firearm and projectile aimed at the midbrain and brainstem]

[b] Front view
front view of a cow showing the brainstem and the entry point at the front of the head
Legend - Operator Standing at Ground Level
Image Description
Level of the brainstem - in the middle of the skull Level of the brainstem - in the middle of the skull
location of the brainstem and midbrain Location of the brainstem and midbrain - middle of the skull
entry point of the projectile Entry point of the projectile (bullet) if the operator is standing at ground level
indicates the direction that the stunning device should be pointed and the entry point Trajectory of the projectile as it travels to the midbrain and brainstem

1.1.2 Mechanical Stunning Devices

1.1.2.1 Captive bolt

  • Use the appropriate landmarks. (See 1.1.1.1.)
  • Do not stun from the top of the head or behind the ears, due to the risk of pithing the animal.
  • Discharge the stunning device perpendicular to the front of the head.
  • For class of animals other than veal calves, the bolt length must be at least 12 cm (4 ¾ in.). The bolt length for bulls must be 15 cm (6 in.).
  • Calibres (diameter) available for the cartridge bolts include .22, .25, and .33.
  • The .25 calibre and larger captive bolt stunning devices with heavier charges are far more effective on bulls than the .22 calibre. (Temple Grandin recommends .25 calibre or larger.)
  • Trigger and contact firing options are available.
  • Use the manufacturer's recommended charge, cleaning, maintenance and stunning protocols.
  • Assess bolt velocity by using the manufacturer's bolt velocity testing device, or similar means. (daily)
Penetrating Captive Bolt
Animal Calibre Bolt Lengths Muzzle Velocity (ft/s)
Calves .22 Depends on size Depends on size
Steers, heifers, cows .22, .25, .33 12 cm (4 ¾ in.)
or 15 cm (6 in.)
≥ 55 m/s (183 ft/s)
Young bulls .22, .25, .33 15 cm (6 in.) ≥ 72 m/s (236 ft/s)
Mature bulls .25, .33 15 cm (6 in.) ≥ 72 m/s (236 ft/s)
(> 100 m/s preferred)

1.1.2.2 Firearms

  • Muzzle (kinetic) energy is frequently used as an indicator of a bullet's destructive potential
  • The heavier the bullet and the greater its velocity, the higher its muzzle energy and capacity for destruction of objects in its path
  • Selection of an appropriate bullet and firearm is critical to good performance when conducting stunning or humane killing
  • Lighter weight, higher velocity bullets can have a high muzzle energy but decreased penetration which can be an issue when penetrating thick bones
  • Use the slowest velocity and minimum energy (muzzle) required to effectively stun the animal.
  • Maximum velocity < 2000 ft/s to help prevent ricochet from the surface of the skull.
  • Maximum energy (muzzle) < 1000 ft/lbs to help prevent skull perforation (exiting the opposite side of the skull).
  • Plan the trajectory so the projectile travels through the midbrain and brainstem, which are located at the level of the bottom of the attachment of the ears. See 1.1 "Important factors" above.
Rimfire Rifle Cartridges
Animal Calibre Grain Muzzle Velocity (ft/s) Energy (ft/lb)
Calves .22 S (short)Table Note 1 29 1095 77
Calves .22 LR (long rifle)Table Note 1 40 1255 140
Steers, heifers, cows .22 LR (long rifle)Table Note 1 40 1255 140
Steers, heifers, cows .22 Winchester Magnum 40 1910 324
Bulls .22 Winchester Magnum 40 1910 324

Table Notes

Table Note 1

Do not use hollow point; use solid point bullets. If possible, .22 Magnum recommended for general use to kill livestock over long rifles.

Return to table note 1  referrer

Centrefire Rifle Cartridges
Animal Calibre Grain Muzzle Velocity (ft/s) Energy (ft/lb)
Large Bulls .30 Remington Carbine 110 1990 967Table Note 2

Table Notes

Table Note 2

Upper limit of energy as the projectile may perforate the skull and enter the neck muscle.

Return to table note 2  referrer

Shotgun Shell
Animal Gauge Length Slug Muzzle Velocity (ft/s) Energy (ft/lb)
Large Bulls .410 2 ½ in. 1/5 oz (87 gr) 1830 651
Large Bulls .410 in. 1/4 oz (108 gr) 1800 788
Ammunition
ammunition

1.2 Electrical

Important Factors:

  • Handling and restraint facilities must meet current industry standards.
  • Individual animal restraint is required.
  • The electrodes are firmly pressed against the animal until stunning is complete. This is to ensure they remain in contact and to facilitate current flow.
  • A water spray is to be used to improve contact.
  • Immediate post stun sticking is required (before or after hanging on line).
  • OSH provisions required due to high amperage and voltage.

1.2.1 Landmarks and approaches

  • Electrodes are firmly pressed against the top of the head (nuchal crest), the chin and the brisket.
  • A two-stage stunning technique must be used; a third stage may be used if required.

1.2.1.1 Phase I - Head-to-head

  • In this stage a current is sent through one electrode that is firmly pressed against the top of the head (usually behind the nuchal crest) and a second electrode is firmly pressed pressed against the chin. (See [a] below.)

1.2.1.2 Phase II - Head-to-brisket (body)

  • Follows phase I
  • In this stage a current is sent through an electrode firmly pressed against the top of the head and a third electrode that has been firmly pressed against the brisket [heart area]. (See [a] below.)

1.2.1.3 Phase III (Optional)

  • Follows phase II
  • This is an optional phase of electrical stunning in bovine.
  • Current is sent from the electrode pressed against the top of the head to a fourth electrode pressed against the spine.
  • This phase is used to minimize post stun kicking. (See [a] below.)
Recommended Electrical Stunning Parameters - Cattle

Phase I - Head to Head

  1. Check the electrical settings as per the following table.
    Electrical settings
    Amperage Frequency Volts Time
    2.0 - 2.5 50 - 60 Hz 400 4 seconds
  2. Apply current; when insensible (unconscious), start Phase II.

    arrow pointing down to next phase

Phase II - Head to Brisket

  1. Check the electrical settings as per the following table.
    Electrical settings
    Amperage Frequency Volts Time
    3 - 4 50 - 60 Hz 450 4 - 15 seconds
  2. There is less kicking with a longer stun, and/or use Phase III spinal depolarization.

    arrow pointing down to next phase

Phase III (Optional) - Head to Spine

  1. Check the electrical settings as per the following table.
    Electrical settings
    Amperage Frequency Volts Time
    3 - 4 50 - 60 Hz 450 as required
  2. Apply current as required.
Landmarks for electrical stunning
[a]
image of a cow with four indications of landmarks for electrical stunning
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