A new study suggests that when calves are slaughtered according to Jewish and Muslim religious law, they really do feel the pain.
"I think our work is the best evidence yet that it's painful," New Scientist quoted Craig Johnson, who led the study at Massey University in Palmerston North, New Zealand, as saying.
Johnson's work is based on findings in human volunteers of specific patterns of brain electrical activity when they feel pain.
Recorded with electroencephalograms, the patterns were reproducible in at least eight other mammal species known to be experiencing pain.
Johnson developed a way of lightly anaesthetising animals so that although they experienced no pain, the same electrical pain signals could be reliably detected, showing they would have suffered pain if awake.
The team first cut calves' throats in a procedure matching that of Jewish and Muslim slaughter methods. They detected a pain signal lasting for up to 2 minutes after the incision. When their throats are cut, calves generally lose consciousness after 10 to 30 seconds, sometimes longer.
The researchers then showed that the pain originates from cutting throat nerves, not from the loss of blood, suggesting the severed nerves send pain signals until the time of death.
Finally, they stunned animals 5 seconds after incision and showed that this makes the pain signal disappear instantly.
"It wasn't a surprise to me, but in terms of the religious community, they are adamant animals don't experience any pain, so the results might be a surprise to them," Johnson said.
Johnson's research, therefore, suggested that if the animal is concussed through stunning, signals corresponding to pain disappear.
The findings increase pressure on religious groups that practice slaughter without stunning to reconsider.
The study has been in the New Zealand Veterinary Journal.