Electromyography of Electrically Stunned Pigs and Excised Bovine Muscle

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Abstract
Electromyographic (EMG) activity was recorded from samples of excised bovine sternomandibularis muscle and from pig carcasses (Yorkshire breed) after electrical stunning at 400 volts. In excised muscle, EMG activity started after a quiescent period of variable duration and was maintained for 1 to 4 hr at temperatures of 26 to 38 C. EMG activity was reversibly inhibited by cooling, was independent of the pH in the core of the sample and possibly originated from the irritability of transected myofibers and nerves on the sample surface. Major bursts of EMG activity in pig carcasses accompanied visible body movements after exsanguination. Suspension of carcasses before exsanguination (one hindlimb shackled to hoist) was accompanied by a low level of EMG activity. EMG activity in shackled hindlimbs revealed the occurrence of isometric muscle contraction concurrent with visible muscle contraction in unrestrained hindlimbs. In the shackled hindlimb, slight EMG activity (not accompanied by muscle movement in unrestrained limbs) between and following bursts of strong EMG activity (induced by exsanguination) continued for a variable period after the start of exsanguination (range, 3 to 38 min; mean 9 min; n = nine pigs). Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.