Origins of movements following stunning and during bleeding in cattle. (December 2015) - Claudia Terlouw, E.M.
Abstract: At slaughter, after stunning, the absence of certain physical signs such as eye movements/reflexes or rhythmic breathing helps determine whether the loss of consciousness was actually achieved. Cattle frequently show movements of neck and/or legs during the post-stun period. We evaluated 1) the origins of these movements in stunned unconscious cattle and 2) relationships with presence of ocular signs or breathing and shot characteristics. In stunned unconscious cattle, movements appear to be reflex-like, generated in the brain stem and/or spinal cord. First, in stunned unconscious cattle, movements could continue until 3 min after the start of bleeding. Second, severing the spinal cord in stunned unconscious cattle did not influence amount of movements. Third, in reaction to the skin cut and sticking, some unconscious animals showed a nociceptive withdrawal reflex. In bulls, following longer stun-stick delays, this response was weaker. Shot placement, post-stun movements and initial bleeding efficiency seemed related but the underlying mechanisms remain to be elucidated. Highlights: Post-stun movements were influenced by shot placement and skull dimensions. Stunned, unconscious cattle may make movements until 3 min following bleeding. These movements appear to be generated in the brain stem and/or spinal cord. In reaction to the bleeding cut cattle may show a nociceptive withdrawal reflex. For bulls, this withdrawal reflex weakened with longer delays until bleeding.