An Examination of the Performance of Blank Cartridges Used in Captive Bolt Devices for the Pre-Slaughter Stunning and Euthanasia of Animals

SIMPLE SUMMARY: In the United Kingdom, the main method of producing unconsciousness in cattle in abattoirs is the captive bolt device. This device comprises a piston (captive bolt) which is driven into the skull of the animal at a speed that renders it unconscious before it can perceive the impact. This speed of operation combined with unconsciousness allows for humane slaughter. The piston is driven forward either by compressed air or rapidly expanding gas from a blank cartridge, with the latter being the most common method. Blank cartridges produce gas by burning propellant and are available in a range of power (more propellant produces more gas which means more power). This paper examines variations in the performance of blank cartridges in producing sufficient velocity and therefore energy to stun animals, thereby affecting animal welfare at slaughter. ABSTRACT: Blank cartridges provide the power source for the majority of captive bolt devices used for rendering animals unconscious prior to slaughter within the United Kingdom or euthanasia worldwide. This paper presents the results of the examination of cartridges as one of the variables that can contribute to an unsuccessful application of this method in practice. Variation was found in cartridge weight, propellant fill volume and velocity within boxes of 1000 cartridges. The variation found was greater in lower charge (1.00 grain) cartridges than in 3.00 grain cartridges, however velocity was found to be variable in both sets. For example, in vivo velocity measurements with 0.25″ calibre 3.00 grain cartridges demonstrated an average velocity of 50.8 m/s over 200 shots with a range of 35.7 to 62.9 m/s when used in the same device. This work demonstrates that variation in cartridge performance does occur and can be due to various factors such as fill volume and propellant function, and simply weighing cartridges cannot be used to determine function, therefore cartridge performance must be a factor that is considered in the event of a miss-stun.