Electrical stunning of cattle

Cattle are normally stunned electrically by three sequential cycles, first a three-second head-only cycle, to stun the animal, secondly a 15-second cardiac cycle, to induce ventricular fibrillation (cardiac arrest), and thirdly a four-second discharge cycle, to reduce convulsions after death. An effective and immediate stun was produced when > or =1.15 amps sinusoidal AC at 50 Hz was applied between the nose and neck electrodes for less than one second. However, when applied for three seconds, head-only currents of >0.46 amp sinusoidal AC at 50 Hz were sufficient to induce epileptiform activity in the brain, identified as high amplitude low frequency activity in the electroencephalogram. The induction of effective head-only electrical stunning resulted in an average interval of 50 seconds before the return of rhythmic breathing movements, and positive corneal and palpebral reflexes. The cardiac arrest cycle successfully induced ventricular fibrillation when >1.51 amps sinusoidal AC at 50 Hz was applied for five seconds between the nose and brisket electrodes.