Relevant Indicators of Consciousness After Head-Only Electrical Stunning in Rabbits, Stunning Efficiency, and Risk Factors in Commercial Conditions

Abstract

This study evaluates the inter-observer repeatability of valid and feasible animal-based indicators (ABIs) for assessing the state of consciousness in rabbits subjected to head-only electrical stunning (HOES). Four observers assessed 11,540 rabbits from 38 batches across 16 commercial slaughterhouses in Europe. Indicators evaluated immediately after stunning included tonic-clonic seizure, breathing, spontaneous blinking, and vocalisation. During bleeding, the same indicators were evaluated with the addition of the righting reflex. Combinations of indicators were analysed to identify associations and the list of relevant indicators. Logistic regression was performed to identify key factors influencing effective stunning. The refined list of indicators for assessing consciousness immediately after stunning comprises tonic-clonic seizure, breathing, spontaneous blinking, and vocalisations. During bleeding, relevant indicators include breathing, spontaneous blinking, and vocalisations. The presence of at least one sign of consciousness of these indicators means the stunning system failed at rendering the rabbit unconscious or the rabbit regained consciousness before death. The prevalence of rabbits showing indicators of persistence or gradual recovery of consciousness within a batch ranged from 0 to 15% immediately after stunning and 2 to 93% during bleeding, underscoring the need for effective monitoring and prompt corrective actions. The identified key factors for effective stunning, listed in order of importance are as follows: maintaining a stun-to-stick interval under 5 s, applying electrical currents above 200 mA with a frequency of 50 Hz, and wetting the rabbits’ heads prior to stunning. These findings provide insights for refining monitoring protocols and improving the welfare of rabbits at slaughter.