School of Agriculture and Forestry
University of Melbourne
Parkville, Vic. 3052 (Australia)
Accepted for publication 28 February 1986
Thirty-six Merino wethers were forced along a sheep race and were either electro-immobilized using a commercially available instrument, restrained with the electro-immobilizer electrodes attached, physically reatrained in a sheep handling machine or allowed to run freely through the race. The degree of aversion shown to the place where the treatment occurred was measured by the time taken by the sheep to run through the race on a subsequent occasion ("transit time") and the push-up time required. All forms of restraint increased the push-up and transit times. Sheep that had been electro-immobilized had a greater average transit time after four treatments and a greater average push-up time after two treatments than sheep that were physically restrained, with or without the electrodes attached. These results suggests that sheep find electro-immobilization more aversive than physical restraint. Push-up time was increased if a high current was used, but was unrelated to the duration of electro-immobilization (up to 3 min). Increasing the current increased the time required by the sheep to recover breathing, which was strongly and positively related to subsequent push-up time. The degree of aversion shown decreases with experience of electro-immobilization.
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