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

## TL;DR

This study identifies reliable signs of consciousness in rabbits after electrical stunning and finds key factors to improve stunning efficiency in slaughterhouses.

## Contribution

The study proposes a refined list of consciousness indicators and identifies key operational factors for effective stunning in commercial rabbit slaughter.

## Key findings

- Tonic-clonic seizure, breathing, blinking, and vocalisation are relevant indicators of consciousness after stunning.
- Maintaining a short stun-to-stick interval, high current, and wetting rabbit heads improves stunning effectiveness.
- Up to 93% of rabbits showed signs of consciousness during bleeding, highlighting the need for improved monitoring.

## Abstract

Head-only electrical stunning (HOES) is the predominant method for stunning rabbits in commercial slaughterhouses. It carries the risk of ineffective stunning and, as a reversible stunning method, regaining consciousness before death through exsanguination. Operators must be trained to recognise signs of consciousness and reapply stunning if necessary to minimise pain and suffering. However, the lack of a standardised list of indicators for assessing consciousness results in variability in evaluations. While the European Food Safety Authority (EFSA) has evaluated the validity and feasibility of such indicators, their repeatability remains underexplored. This study aims to assess the repeatability of valid and feasible consciousness indicators to evaluate the efficiency of stunning, with the goal of proposing a refined list of indicators for use in commercial slaughterhouses. The findings offer insights for improving animal welfare standards and developing standardised monitoring protocols for consciousness assessment.

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.