Stunning

[1] A primitive form of stunning was used in premodern times in the case of cattle, which were poleaxed[broken anchor] prior to being bled out.

However, prior to slaughter pistols and electric stunners, pigs, sheep, and other animals (including cattle) were simply struck while fully conscious.

The belief that it was unnecessarily cruel to slaughter an animal against its will eventually led to the compulsory adoption of stunning methods in many countries.

One of the first campaigners on the matter was the eminent physician, Benjamin Ward Richardson, who spent many years of his later working life developing more 'humane' methods of slaughter.

As early as 1853, he designed a lethal chamber that would gas animals to death supposedly painlessly and without their knowledge, and he founded the Model Abattoir Society in 1882 to investigate and campaign for other methods of slaughter.

[4][non-primary source needed] Modern methods, such as the captive bolt pistol and electric tongs were required and the Act's wording specifically outlawed the poleaxe.

The CrustaStun is a device designed to administer a lethal electric shock to shellfish (such as lobsters, crabs, and crayfish) before cooking.

[5] With gas stunning animals are exposed to a mixture of breathing gases (argon and nitrogen for example) that produce unconsciousness or death through hypoxia or asphyxia.

After confirmation of the first U.S. BSE case, FSIS issued regulations (69 FR 1887, 12 January 2004) prohibiting the use of the most widely used stunning device (air-injection captive bolt stun gun) because the compressed air device (in contrast to the blank cartridge-driven or non-penetrating captive bolt) has been shown to force pieces of brain and other central nervous system (CNS) tissue into the bloodstream.

Cattle blood is processed primarily for use as a protein supplement in animal feeds and milk replacer for calves, and could transmit BSE if it contained specified risk materials (SRMs include brain and CNS tissue).