Assessing pig welfare at stunning in Northern Italy commercial abattoirs using electrical method

SUMMARYto Council Regulation 1099/2009 regular checks at stunning are compulsory to ensure that the animals do not present any signs of consciousness or sensibility in the period between the end of the stunning process and death. So far there are no data available on the prevalence of correctly electrically stunned pigs in Italy and on the signs more effective to use in practice to evaluate poorly stunned animals or return of consciousness. The aim of this study was to evaluate the prevalence of correctly stunned pigs by electrical stun in Italian commercial abattoirs through the clinical analysis of signs of consciousness. Four commercial abattoirs using three different electric stunning systems were studied to assess the efficiency of stunning. The abattoirs A and C used head-only manual stunning with an intensity ≥ 1.3A; the abattoir D used head-only manual stunning with an intensity 0.4 - 2A and the abattoir B used head-heart automatic stunning with an intensity ≥ 2.5A and ≥ 1A for the head and the chest respectively. A total of 1620 heavy pigs were evaluated from stunning to complete bleeding to evaluate the presence of signs of consciousness (animal alert, presence of rhythmic breathing, head uplift, pain reaction) and other signs (vocalizations, tongue movements, etc.). At the end of the observation the evaluator expressed a judgment concerning the state of consciousness for each pig conscious: presence of rhythmic breathing and/or pain reaction and/or righting reflex and/or the animal appeared alert; unconscious: presence of loss of posture, tonic phase, and clonic phase (not for head-heart automatic stunning); absence of rhythmic breathing, pain reaction, righting reflex; doubtful: not clear presence of rhythmic breathing or pain reaction or righting reflex. A statistically significant difference was observed in the distribution of the state of consciousness between the different abattoirs (p=0.01) and between the three different stunning systems (p=0.04). Abattoir B resulted to be more efficient (0% conscious; 0.25% doubtful) in stunning, compared to the others: abattoir A (0.5% conscious; 1.5% doubtful); C (2% conscious; 0.5% doubtful); D (1.7% conscious; 0.7% doubtful). Pain reaction, rhythmic respiration and head uplift could be used as practical key parameters for a regular evaluation of stunning, however future investigations are needed to better clarify their effectiveness taking into consideration the site of application of tongs and the current applied to each animal. The importance of tongue movements in apparently unconscious animals should be also investigated with more attention. No correlation was found between the state of consciousness and any of the anamnestic variables considered (signs of recent fighting; weight higher or lower than the range; signs of stress).