Factors affecting the effectiveness of head-only electrical stunning in sheep

The effects of factors such as the position of the tongs, the presence of wool, and the wetness of the skin on the efficiency of the head-only stunning procedure, and the duration of the periods of unconsciousness and analgesia were studied in lambs. The degree of insensibility was determined from the evaluation of physiological responses and electroencephalograms. The proportion of successfully stunned animals was significantly higher (P<0-05) in the animals stunned with the tongs in a frontal position than in those stunned with them in a caudal position, in the animals stunned with wet electrodes than in those stunned with dry electrodes and also in the animals without wool than in those with wool. The interval between stunning and sensibility to pain was affected significantly (P<0-01) only by the position of the tongs, being longer in animals with them in a frontal position than in those with them in a caudal position.