Abstract
BACKGROUND: Slaughterhouses for all animals, including reindeer, must achieve the goal of high animal welfare. They must carry out regular checks on stunning effectiveness and key parameters to ensure that animals do not display any signs of consciousness, and display the expected signs of unconsciousness, in the period between stunning and death. The official control verifying this performance must be based on scientific evidence. Experience gained and scientific development are to be considered when control and regulations are developed. The purpose of this study was to evaluate penetrative captive bolt-stunning quality in stunning of reindeer (Rangifer tarandus tarandus L.). We investigated stun-to stick interval in relation to indicators of consciousness and unconsciousness as well as factors affecting the time between stunning and sticking to generate evidence-based knowledge for optimising animal welfare by best practise at stunning. Stun-to-stick interval was measured for 1,590 reindeer during eight slaughter days at two abattoirs during slaughter season 2015-2016. The variables recorded were abattoir (AA, AB), season, type of stunning (cartridge-powered/ pneumatic captive bolt gun), level of experience of the stunning operator (one/three/five years), animal category (calf/male/female), and origin of the reindeer (mountain/forest), number of stunning attempts per reindeer, indicators of possible remaining or regaining of consciousness and indicators of unconsciousness until the end of bleeding. RESULTS: Mean stun-to-stick interval for effective stuns was 44.1 s (95% confidence interval (CI 95%) = 43.6-44.6). Longer stunning experience was associated with shorter mean stun-to-stick interval (P < 0.001) as well as a quicker slaughter hoisting process in one of the two abattoirs (P = 0.016). In 5.3% (83/1,569) of one-shot stuns, stun-to-stick interval exceeded 60 s, where stunning operators with short experience had significantly more cases than more experienced operators (P < 0.001). Ineffective stuns (> one shot/reindeer), with continued standing posture of a reindeer post-shot, comprised 1.3% (21/1590) of all stuns with significant relationship to adult male reindeer and none to stunning operator experience. CONCLUSIONS: Proper standard operating procedures including maintain of equipment as well as a supervised training period for operators as suitable risk management activities are recommended. Official controls could be most effective by focusing on these factors.