Annex A - Species-Specific Stunning Guidelines - Red Meat Species
4. Bison

4.1 Mechanical

Important Factors:

4.1.1 Handling and restraint

  • Handling and restraint facilities must be sturdy and meet current industry standards for bison, including safety measures and sight lines.
  • Suitable facilities are essential.
  • Restraint must facilitate stunning the animal from the front of the head.

4.1.2 Landmarks and approaches

  • Mature bulls have very thick frontal bones overlaying the brain. The hide over the frontal bone and the frontal bone itself can each be up to 1.5 in (3.8 cm) thick.
  • Mature bulls frequently have long thick hair on their heads, which makes it difficult to see landmarks other than the horns.
  • Bison typically hold their heads lower than cattle.
  • Know the approximate location of the brain in the skull.
  • Plan the trajectory so that the bolt/projectile travels through all parts of the brain (cerebral hemispheres, midbrain, brainstem). Of these the midbrain and brainstem are the most important parts of the brain. They are located in the centre of the brain at the level of the attachment of the ears. (See [d].)
  • Landmarks are very important and they are not the same as for cattle. (See [a] to [i] below.)
  • Intersection of the midpoint of the front of the head and a line running between the lower part of the attachment of each horn. (See [b], [e], [f] and [h] below.)
  • Discharge the stunning device perpendicular to the front of the head. (See [a], [c], [d], [g] below.)
  • Do not stun from the top of the head or behind the head, or behind the ears, due to the risk of pithing the animal instead of properly stunning it.
  • Discharging the mechanical stunning device at the locations on the skull other than the front of the head is not permitted due to the risk of missing the appropriate sections of the brain.
  • Stunning problems are usually due to using improper landmarks and/or holding the mechanical stunning device at an angle other than perpendicular to the skull. (See [a] to [i] below.)

Proper Landmarks for Stunning

Mature males
[a]
mature male bison - side view with arrow pointing to stun site
[b]
mature male bison - front view with indication of the entry point for the projectile
[c]
mature male bison - isometric view with arrow pointing to stun site
Immature Males
[d]
bison immature male - side view with location of brainstem and midbrain indicated and arrow pointing to stun site
[e]
bison immature male - front view with entry point of the projectile indicated
Mature Female
[g]
bison mature female - side view with arrow pointing to stun site
Projectile Entry Point
[e]
bison immature male - front view with entry point of the projectile indicated

[f]

bison skull - top view with arrow pointing to properly located bullet hole
Projectile entry point

Projectile Entry Point

[e]
bison immature male - front view with entry point of the projectile indicated

[h]

bison skull - top view with arrow pointing to properly located bullet hole and imaginary line from the base of one horn to the othe
Projectile entry and imaginary line from the base of one horn to the other
Legend - proper landmarks for stunning bison
ImageDescription
line from the base of one horn to the other Line running from the base of one horn to the other.
location of the brainstem and midbrain Location of the brainstem and midbrain - in the middle of the skull.
entry point of the projectile Entry point of the projectile (bullet).
trajectory of the projectile Trajectory of the projectile as it travels to the midbrain and brainstem.
arrow indicating projectile entry point Arrow indicating projectile entry point to the skull and brain cavity.

Improper Landmarks for Stunning

Bison Skull
[i]
bison skull - top view with arrow pointing to properly located bullet hole

Note: This is an example of the impact of using improper landmarks. This bison skull contained 10 bullet holes. They were in the front, side and back of the skull. Most of the bullet holes in the front are too low (bovine landmarks), or too much off the midline of the skull (thereby missing the midbrain and brainstem) to be effective.

4.1.3 Mechanical Stunning Devices

4.1.3.1 Captive Bolt

  • The bolt length for immature animals must be at least 12 cm (4 ¾ in); the bolt length for animals over one year of age must be at least 15 cm (6 in).
  • The .25 calibre and larger captive bolt stunning devices with heavier charges are far more effective.
  • Use the manufacturer's recommended charge, cleaning, maintenance and stunning protocols.
  • Assess bolt velocity daily by using the manufacturer's bolt velocity testing device, or similar means.
  • Can be used on immature animals.
  • See 4.1.2 Landmarks and approaches for stunning problems.

Note: Standard bolts are not long enough for large bulls.

Penetrating Captive Bolt
AnimalCalibreBolt LengthMuzzle Velocity (ft/s)Energy (ft/lb)
Immature > .25 > 12 cm (4 ¾ in)
or 15 cm (6 in)
> 72 m/s (236 ft/s) Heavy Charge
Over one year
of age
>.25 15 cm (6 in) > 72 m/s (236 ft/s) Heavy Charge

4.1.3.2 Firearms

  • Perforation and ricochet are a safety concern with high velocity calibre firearms.
  • Use the slowest velocity and minimum energy required to effectively stun the animal.
  • Maximum velocity < 2000 ft/s to help prevent ricochet from the surface of the skull.
  • Maximum energy < 1000 ft/lb to help prevent skull perforation (exiting the opposite side of the skull).
  • Plan the trajectory so that the bullet travels through the midbrain and brainstem, which are located below the horn and between the ears.
  • See 4.1.2 above for stunning problems.
Rimfire Rifle Cartridges
AnimalCalibreGrainMuzzle Velocity (ft/s)Energy (ft/lb)
Immature + Cows .22 Winchester Magnum 40 1910 324
Centrefire Rifle Cartridges
AnimalCalibreGrainMuzzle Velocity (ft/s)Energy (ft/lb)
Mature Bulls .30 Remington Carbine 110 1990 967Table Note 1

Table Notes

Table Note 1

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

Return to table note 1 referrer

Shotgun Shell
AnimalGaugeLengthSlugMuzzle Velocity (ft/s)Energy (ft/lb)
Mature Bulls .410 2 ½ in 1/5 oz (87 g) 1830 651
Mature Bulls .410 in ¼ oz (108 g) 1800 788
Ammunition
ammunition
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