RESUMEN
A total of sixty-two calves with body weights of 200 kg and with preimplanted ECoG electrodes on the dura mater, were electrically stunned using various currents, voltages and stunning equipment. To stun 90% of the calves effectively, a current strength of 0·87 A is estimated to be necessary when using scissor model tongs. Effective stunning means immediate (within 1 s) induction of unconsciousness by a general electroplectic insult. Atrial fibrillation is a frequently occurring phenomenon after electrical stunning when the electrodes are placed between the eye and the ear. The relatively short duration of the insult in calves compared with pigs, as well as the clonic spasms occurring 10s after stunning, are major drawbacks to the practical application of electrical stunning of veal calves. The experiments show that these drawbacks can be eliminated by modifying the form and position of the electrodes.
RESUMEN
Captive bolt stunning frontally, occipitally and on the nape of he neck was studied in 30 veal calves. The state of consciousness was judged from the electroencephalogram (EEG) recorded via surgically pre-implanted electrodes frontally on the right side of the head. Frontal stunning on the left side of the head and occipital stunning almost certainly ensured immediate unconsciousness because delta and theta waves (tending to an iso-electric line) appeared on the EEG directly after stunning. Additionally the corneal reflex was absent. Occipital placing did not result in macroscopical damage to the cortex as did frontal stunning. Shooting witha captive bolt in the nape of the neck caused unconsciousness after mean (+/- sd) 21 +/- 6 seconds. Until then the calves were fully conscious, according to the electroencephalogram and also showed a positive corneal reflex. It is therefore suggested that for the sake of animal welfare captive bolt shooting at the nape of the neck should be abandoned.
Asunto(s)
Mataderos , Bovinos/fisiología , Inmovilización , Animales , Estado de Conciencia/fisiología , Córnea/fisiología , Electrodos Implantados/veterinaria , Electroencefalografía , Masculino , Métodos , Reflejo/fisiologíaRESUMEN
In experiments with carbon monoxide euthanasia in 30 piglets, carbon monoxide was administered rapidly (five to 10 minutes), slowly (45 minutes) or in combination with nitrous oxide (15 minutes). When carbon monoxide was administered at a fast flow rate, visual signs of severe excitation were observed (sometimes before unconsciousness). With low carbon monoxide flow rates, and in particular, when carbon monoxide was combined with nitrous oxide, excitation was less evident and only occurred after unconsciousness.