New Zealand is well advanced in slaughter practices in all meat works, where cattle, sheep, goats, and pigs are electrically stunned before their throats are cut severing the carotid arteries. The interval between stunning and sticking (bleeding) is well within the requirement of overseas markets, and research is constantly advancing technology to shorten this interval and prevent animal suffering at slaughter.
The concern now is for sheep that are slaughtered on farms for home consumption and for dog tucker. These sheep simply have their throats cut and then their necks broken severing the spinal cord. Skilled operators do both these actions with one blow of the knife and a twist of the head around the left leg.
In the past, we have assumed that cutting a sheep's throat using a sharp knife to cut both carotid arteries and the jugular veins in one swift stroke while subsequently breaking its neck produced complete insensibility to pain. But an investigation by the late Professor David Blackmore, has shown that our long-held assumption to be wrong.
Research on sheep has shown that the brain may react to pain after the throat has been cut and until the animal becomes unconscious through lack of oxygen. And whether the neck is broken and the spinal cord severed makes no difference. Professor Blackmore believed that attempting to sever the spinal cord could easily add to the pain felt by the animal before it dies. In addition, it does not affect the time it takes for the sheep to become unconscious and adds to the potential pain and distress of the procedure.
So the main question for shepherds killing sheep for the house or the dogs is how to kill sheep humanely, after 150 years of cutting their throats!
The most important thing to remember is that the humane destruction of sheep must be conducted in a manner that minimises unnecessary pain and distress prior to death, and the person doing it should be competent.
The spinal cord should not be severed or broken until after death.
A properly positioned captive bolt or firearm will dispatch animals in a humane manner but few farmers have these. The correct position for stunning hornless sheep is the highest point on the head, and on the mid-line, aiming straight down. An effective shot with .22 rifle will do the job correctly, but care must be taken to prevent stray bullets ricocheting. It's very important to know the correct position on the animal's head to aim the shot.
The .22 bullet should enter the sheep’s head along its midline, from the front. If you are not sure of the correct position, then check with your veterinarian.
If you cannot shoot the sheep using a captive bolt or a .22, then it should be rendered insensible rapidly, and remain in that state until death. This can be achieved by a blow on the correct position above the brain with a heavy blunt instrument (just be aware this is not OK for calves). Then the sheep’s throat should be cut immediately to prevent any possibility that it may recover consciousness. The overriding concern should always be to prevent the sheep from suffering further pain and distress.