Heart Beat, Blood Pressure, Respiration, and Brain Waves of Broilers as Affected by Electrical Stunning and Bleed-Out

Abstract

Three electrical circuits were utilized to stun male broilers prior to the slaughter process. Before and after stunning, four physiological variables were measured: blood pressure, brain waves, and heart and respiratory rates. Based upon maximal bleed-out, the circuits were rated in the following order (maximal to minimal percent bleed-out): high frequency (HF), alternating current (AC), and direct current (DC). An attempt was made to correlate maximal bleed-out with the rate of change in heart rate and blood pressure following stunning for each electrical circuit. No correlation was found. It is suggested that the distribution of blood after stunning may be a more significant factor than the effect of a stun on heart rate and blood pressure. Perhaps both the high frequency and AC circuits effect better bleed-out by shunting more blood from peripheral regions to the viscera. Data suggest that the current industry practice of allowing a 10—15 sec. time interval between stunning and the severance of neck blood vessels is a reasonable one, in that it allows heart rate to return to normal levels prior to venesection.Brain waves were monitored before and after electrical stunning. In addition, simple sensory stimuli tests were conducted in an attempt to ascertain the humaneness of the slaughter process. The sharp decrease in brain activity following stunning and lack of response by broilers to painful stimuli suggest that it is a humane practice to electrically stun broilers as the initial step of processing poultry.