Solving return-to-sensibility problems after electrical stunning in commercial pork slaughter plants
Temple Grandin
Department of Animal Science
Colorado State University
Fort Collin, Colorado, USA
Journal of American Veterinary Medical Association, 2001, Vol. 219:608-611
Objective
To determine causes and solutions for return-to-sensibility problems after electrical stunning in pigs.
Design
Case Studies
Sample Population
6 federally inspected pork slaughter plants
Procedure
One hundred to 200 pigs were scored in each plant for stunner positioning, squealing when stunner was applied, and signs of insensibility. All pigs were held in a V-shaped restrainer conveyor and stunned with a manually applied head-to-body electrical stunner.
Results
Percentage of pigs that had blinking after stunning ranged from 0.5 to 7. None of the pigs had a righting reflex or kicked in response to stimuli. All signs of possible return to sensibility disappeared before bleeding pigs reached the scalding tub. Spontaneous eye blinking was eliminated by improving bleeding practices to increase blood flow, ergonomically redesigning the stunner operator's work station to make correct placement of the stunner easier, redesigning the head electrode to facilitate correct placement, reducing line speed from 1,200 to 1,080 head/hr, correcting problems with poor initial contact of the stunner, and increasing amperage of a stunner that was set too low for sows. In 1 plant, a fatigued operator was the cause of stunner placement mistakes that resulted in signs of returning to sensibility.
Conclusions and Clinical Relevance
Problems with electrial stunning can be easily corrected, but effective stunning requires monitoring of correct electrode placement, amperage, and bleeding procedures. Observation of spontaneous natural eye blinking without touching the eye is recommended for use under field conditions, because it is less prone to misinterpretation than are other methods.
Click here to return to the Homepage for more information on animal behavior, welfare, and care.