Effect of slaughter on the spontaneous and evoked activity of the brain.

The principal blood vessels in the neck which are severed at slaughter in commercial poultry processing plants are described. Mechanical slaughtering methods often severed the spinal cord without cutting the carotid arteries. The manual method of slaughter cut one carotid artery plus one jugular vein. The effects of 9 different slaughtering methods on spontaneous and evoked electrical activity in the brain were examined in anaesthetised chickens and ducks. Severing the spinal cord without cutting the carotid arteries was found to result in death from asphyxia, and cutting one carotid artery plus one jugular vein was one of the slowest methods of killing the birds. Inducing a cardiac arrest at electrical stunning was the quickest method of inducing death. Spontaneous activity in the brain was lost before visual evoked activity. The times before loss of spontaneous activity varied between 23 and 233 s according to the method of slaughter and loss of evoked activity ranged between 90 and 349 s after slaughter.