Following a request from the European Commission, the Panel on Animal Health and Welfare was asked to deliver scientific opinions on monitoring procedures at slaughterhouses for different animal species, stunning methods and slaughter without stunning.
In particular, the opinions will (i) provide indicators assessing signs of (a) consciousness, in the case of slaughter with stunning, and (b) unconsciousness and (c) death of the animals, in the case of slaughter without stunning, which have been selected based on their performance (i.e. sensitivity, specificity and feasibility of the indicator); (ii) indicate the most common risk factors and their welfare consequences to determine the circumstances of the monitoring procedures; and (iii) provide examples of sampling protocols, based on different possible scenarios.
The current opinion deals with the assessment of consciousness in poultry after stunning with waterbaths or gas mixtures and the assessment of death in poultry during slaughter without stunning.
The Panel on Animal Health and Welfare agreed that, although it is traditional to look for outcomes of unconsciousness in poultry following stunning, the risk of poor welfare can be detected better if bird welfare monitoring is focused on detecting consciousness, ie. ineffective stunning or recovery of consciousness. Therefore, the indicators were phrased neutrally (eg. corneal reflex) and the outcomes were phrased either suggesting unconsciousness (eg. absence of corneal reflex) or suggesting consciousness (eg. presence of corneal reflex). This approach is commonly used in animal health studies (eg. testing for the presence of a disease) but very new to animal welfare monitoring in slaughterhouses.
A toolbox of selected indicators is proposed to check for signs of consciousness in poultry after stunning with waterbaths or gas mixtures; a different toolbox of indicators is proposed for confirming death of the birds following slaughter without stunning. Various activities (two stakeholder consultations, a systematic literature review, an online survey addressed to experts involved with monitoring welfare at slaughter) were carried out in order to obtain information on the sensitivity, specificity and feasibility of the indicators. Based on such information, the most appropriate indicators were selected and a toolbox of indicators to be used in monitoring procedures was proposed. The use of animal-based indicators is similar to the use of a diagnostic or statistical 'test' with either a positive or negative outcome. In the case of slaughter with stunning of poultry, the major interest is to detect the undesired outcome, namely the presence of consciousness in birds. The toolbox proposes indicators and their outcomes. In the case of slaughter without stunning, the interest is to detect whether the animals become unconscious and to detect when the animal dies, as this determines the start of the next operational phase at the slaughterline. However, the indicators applied for this task also have to correctly detect animals as conscious or alive. The toolbox proposes indicators and their outcomes.
Each of the toolboxes provides a set of recommended indicators and another set of additional indicators. The people responsible for monitoring have to choose the most appropriate set of indicators (at least two indicators) from these toolboxes according to their expertise and the available infrastructure in a slaughterhouse.
Toolboxes for slaughter with prior stunning using electrical waterbath:
After stunning of the birds prior to slaughter the indicators should be repeatedly checked to detect signs of consciousness through the two key stages of monitoring during the slaughter process: between the exit from the waterbath stunner and neck cutting (key stage 1) and during bleeding (key stage 2).
The recommended indicators in Toolbox 1 (for monitoring between the exit from the waterbath stunner and neck cutting) are tonic seizures, breathing and spontaneous blinking. Additionally, the corneal or palpebral reflex and vocalisations may be used. In Toolbox 2 (for monitoring during bleeding) the recommended indicators are wing flapping and breathing. In addition, the corneal or palpebral reflex, spontaneous swallowing and head shaking may also be used.
Toolboxes for slaughter with prior stunning using gas mixtures:
After stunning of the birds with gas mixtures prior to slaughter, the indicators should be repeatedly checked to detect signs of consciousness through the two key stages of monitoring during the slaughter process: between the exit from the gas stunner and the entrance to the scalding tank, especially during shackling (key stage 1) and during bleeding (key stage 2).
The recommended indicators in Toolbox 3 (for monitoring between the exit from the gas stunner and neck cutting, especially during shackling) are breathing, muscle tone, wing flapping and spontaneous blinking. Additionally, the corneal or palpebral reflex and vocalisations may be used.
In Toolbox 4 (for monitoring during bleeding) the recommended indicators are wing flapping, muscle tone and breathing. In addition, the corneal or palpebral reflex may also be used.
Toolboxes for slaughter without stunning:
In the case of slaughter without stunning, all birds should be checked to confirm death before undergoing scalding. Moreover, consciousness or life in checked animals should be correctly identified. On this basis, the indicators were selected for the toolbox.
The recommended indicators in Toolbox 5 (for monitoring death before scalding) are breathing, the corneal or palpebral reflex, pupil size and bleeding. Additionally, muscle tone may be used.
The personnel performing stunning, and/or bleeding will have to check all birds to rule out the presence of consciousness following electrical waterbath or gas stunning or confirm death during slaughter without stunning. The person in charge of monitoring the overall bird welfare at slaughter (ie. animal (poultry) welfare officer) has to check a certain sample of slaughtered birds for approval. A mathematical model is proposed which can be used to calculate the sample size that he/she needs to check at a given throughput rate (total number of animals slaughtered in the slaughter plant) and threshold failure rate (number of potential failures—birds that are conscious after electrical waterbath or gas stunning). Finally, different risk factors and scenarios are proposed to define, in addition to a 'normal' sampling procedure, a 'reinforced' protocol to be used if particular circumstances and needs of the slaughterhouse so requires.