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Early June 1977 the Clinic for small clawed animals and forensic medicine and mobile clinic of the veterinary university of Hanover published a short report on this research brief (Hazem, A.S., Gross, R., Schulze, W., 1977).
These documents reveal the following: The investigations carried out aimed at providing objective data for the evaluation of ritual slaughter from an animal welfare legislation point of view. As part of the research project the effectiveness of captive bolt stunning was first analysed using EEG. Comparable data about the ritual slaughter were then gained using the same method of deduction and evaluation. The ritual cut experiments were carried out on 17 sheep of the breed “black headed meat sheep” and 15 calves of various breeds. To further investigate the occurrence of low frequency potentials in sheep stunned by captive bolt followed by a bloodletting cut, six sheep were stunned in a second phase of the experiment by captive bolt and then bled at various intervals.
The approach of these studies can be summarised as follows:
Experiments for measuring the heart frequency and brain activity during slaughter conditions were carried out on 23 sheep and 15 calves. After implanting permanent electrodes into the Os frontale the cerebral cortex impulses were measured for 17 sheep and 10 calves during ritual slaughter and for 6 sheep and 5 calves during captive bolt application with subsequent bloodletting. Some sheep were additionally subjected to thermal pain stimuli after the ritual cut.
The investigations had the following results:
a) For slaughter by ritual cut:
1. After the bloodletting cut the EEG initially is the same as the EEG before the cut. There is a high probability that the loss of reaction took place within 4 – 6 seconds for sheep and within 10 seconds for calves.
2. The zero line in the EEG was recorded no later than after 13 seconds for 17 sheep and no later than 23 seconds for 7 calves.
3. Thermal pain stimuli did not cause an increase in activity.
4. After the cut the heart frequency rose for calves within 40 seconds to 240 heart actions per minute and for sheep within 40 seconds to 280 heart actions per minute.
b) For slaughter after captive bolt application:
1. After captive bolt stunning all animals displayed most severe general disturbances (waves of 1-2 Hz) in the EEG, which almost with certainty eliminates a sense of pain.
2. The zero line in the EEG was reached for 4 calves after 28 seconds.
3. For two sheep the cerebral cortex activity only stopped in one half of the brain, whilst it continued in the other in the –region (up to 3.5 Hz) until the bloodletting cut.
4. The bloodletting cut resulted for all animals in a brain activity (e and d waves).
5. Thermal pain stimuli caused an increase in activity in one sheep.
6. The heart frequency rose directly after stunning to values above 300 actions per minute.
In summary the following conclusions are possible:
1. Slaughter after captive bolt stunning
A. Calves
After captive bolt stunning most severe general disturbances (waves of 1-2 Hz) occurred in the EEG, which almost with certainty eliminates a sense of pain.
B. Sheep
Similar disturbances were also seen in sheep, but besides the somewhat higher frequency there are still clearly superimposed waves. For one animal waves could be recorded after pain stimuli until after the 200th second. Apparent cramps were registered for all sheep with the exception of one animal.
2. Slaughter in the form of ritual cut
A. Calves
After the bloodletting cut loss of reaction (loss of consciousness) occurred with high probability within 10 seconds. A clear reaction to the cut could not be detected in any animal. For 7 animals a zero EEG was recorded no later than after 23 seconds. Cramps occurred in the animals regularly only after the brain currents had stopped.
B. Sheep
After the bloodletting cut loss of reaction (loss of consciousness) occurred after 10 seconds the latest. A clear reaction to the cut could not be detected in any animal. The zero line was recorded no later than 14 seconds after the cut. Cramps only occurred after the zero line had been detected and were much shorter than after captive bolt stunning.
The slaughter in the form of ritual cut is, if carried out properly, painless in sheep and calves according to the EEG recordings and the missing defensive actions.
During the experiments with captive bolt stunning no indications could be found for proscribing this method for calves.
For sheep, however, there were in parts severe reactions both to the bloodletting cut and the pain stimuli. A proof of the reliable effectiveness of captive bolt stunning could not be provided using the methods applied.
These first experiments carried out under clinical conditions and the insights for the correlations of sensory physiology during stunning/slaughter of small ruminants initially lead to the following factual and legal considerations for the preparation of legislation:
These experiments on sheep and calves carried out within a clinic show that during a ritual slaughter, carried out according to the state of the art using hydraulically operated tilting equipment and a ritual cut, pain and suffering to the extent as has since long been generally associated in public with this kind of slaughter cannot be registered; the ritual slaughter carried out under these experimental conditions complies with the requirements of article 4 para. 1 TierSchG. The EEG zero line – as a certain sign of the expiration of cerebral cortex activity and according to today’s state of knowledge also of consciousness – occurred generally within considerably less time than during the slaughter method after captive bolt stunning.
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