WELFARE OF CALVES .2. INCREASE IN VERTEBRAL ARTERY BLOOD-FLOW FOLLOWING EXSANGUINATION BY NECK STICKING AND EVALUATION OF CHEST STICKING AS AN ALTERNATIVE SLAUGHTER METHOD

The role of the vertebral arteries in delaying loss of sensibility following neck sticking in slaughter calves was investigated. Vertebral artery blood flow was measured using probes before, during and after electrical stunning and slaughter. Systemic blood pressure, electrocorticogram, visually evoked responses and the occurrence of carotid occlusions were also recorded. When carotid occlusion occurred, the time to onset of brain failure was delayed based on the development of an isoelectric state. In addition, when carotid occlusion occurred the mean arterial blood pressure was sustained for longer following slaughter, and concurrently vertebral artery bload flow could be maintained at about 30% of its initial level for up to 3 min. In some animals vertebral artery flow increased substantial following sticking. When chest sticking was used no occlusion of vessels occurred mean arterial blood pressure fell promptly (within 8 s) and the onset of an isoelectric state did not extend beyond one minute. In addition, visually evoked responses were not present after 5 s following chest sticking.