The practice of certain religions requires animals to be slaughtered according to rules defined by ritual. These may involve slaughtering animals while they are conscious, such as by using a knife to drain them of blood.
Such religious rituals were originally defined to maximize hygiene and minimize pain to the animals. Because of the long period since the rituals were laid down, sanctity has come to surround the origins of them and present day leaders are reluctant to introduce the more humane methods which technology has developed in the meantime.
Ritual slaughter may be practised in a country where the particular ritual is part of the state religion, or it may be practised by a minority. In terms of total suffering of animals, the most important rituals are: Halal (practised by Moslems), Shehita (practised by Jews) and Jatka (practised by Sikhs). Halal on sheep and goats consists of cutting the throat and bleeding to death in order to remove as much blood as possible (tests now show that more blood actually remains in the flesh of animals killed ritually than when they are first made unconscious before bleeding). For Shehita a knife is used to cut the throat and major blood vessels in order to remove the maximum amount of blood. Jatka consists of the decapitation, usually by a single stroke, of sheep, goats and cattle. Many ancient African traditions, including animal sacrifice, have been integrated by independent churches into their interpretation of Christianity, thus contributing to their extraordinary popularity.