Summary
Background
It is a requirement of meat production that animals processed are handled and slaughtered in a humane manner. Therefore, most animals are stunned prior to exsanguination, so that they are insensible throughout the process of sticking, and remain insensible until death has ensued. However, animals processed for the Muslim market (Halal meat production) are subject to the requirements of the relevant religious texts (the Al Qu'ran and Hadith), and there is often a conflict in opinion over the suitability of stunning procedures when slaughtering an animal for human consumption. The basic requirements of the religious texts are that the animal is healthy and handled in such a way that it is not injured at the time of carrying out the ritual slaughter cut for exsanguination. Thus, mechanical means of stunning, that cause skull damage, or those that result in the death of the animal, are not approved for the religious markets. Any method used to induce insensibility must not cause injury, and must be fully recoverable. In Australia, all cattle processed for the Halal market are stunned prior to slaughter, using a non-penetrating mechanical stun, referred to as a percussive, or non-penetrative stun. The requirements of the Malaysian Halal market demand that this percussive stun does not result in damage to the skull and low power compressed air systems are therefore used in commercial plants to deliver the stun. There are queries over the efficacy of low power percussive stunning in induction of insensibility, such that some countries have outlawed its use. If the animal is not properly stunned, there is the possibility that it will experience pain and suffering at the time of the neck cut.
The Malaysian Department of Veterinary Services, JAKIM and the National Fatwa Council approved the application of pre-slaughter electrical stunning (24 November 1988). Stunning procedures include the use of electrical stunning, penetrating and non-penetrating (percussive) captive bolts. One of the adverse effects of electrical stunning in cattle is that it may cause ecchymoses or petechial haemorrhage. JAKIM accepts non-penetrating percussive stunning (mushroom head) cattle but not penetrating captive bolt stunning. The basis for this is that mushroom head stunning is believed to be reversible while penetrating stunning is non-reversible. The magnitude of suffering or physiological stress reactions as a result of the non-penetrative or penetrative percussive stunning itself has yet to be satisfactorily ascertained. In Nov 2005 Department of Veterinary Services, JAKIM and the National Fatwa Council (NFC) approved post slaughter thoracic sticking (24 November 2005) procedures as practiced by major meat exporters like Australia and New Zealand. Hence, further studies were needed to provide insights into the physiological stress responses, welfare and meat quality of cattle following stunning, slaughter and sticking.
Research
Researchers at the Universiti Putra Malaysia approached CSIRO and MLA with a proposal to compare different methods of slaughter in terms of physiological stress, Electroencephalogram (EEG) changes and meat quality. Most of the published work on slaughter using different stunning and sticking methods focuses on individual aspects of animal welfare or meat quality. This study aimed to provide a comparative analysis of the effects of penetrative stunning, non-penetrative stunning, post-slaughter stunning and sticking by the 'thoracic' method versus non-thoracic sticking on physiological and biochemical parameters associated with stress in animals, and on meat quality.
The overall aims of project P.PIP.0197 and its associated communication project A.MFS.0167 were to:Evaluate the effects of stunning, slaughter and thoracic stick (according to Halal standards) on physiological stress reactions, cessation of vital functions (brain and heart electrical activities) and meat quality in beef cattle.Collect information to support application to JAKIM relating to halal slaughter procedures to be used in Australian meat processing plants
CSIRO hosted a visiting researcher from the Universiti Putra Malaysia for a period of 6 months in 2009 in order to facilitate sample collection. The study was carried out in a commercial abattoir. Ten animals were assigned to each treatment group (Unstunned, neck stick only; Penetrative stun with neck stick; Low Power Percussive Stun with neck stick; High Power Percussive Stun with neck stick; Penetrative stun with neck stick followed by thoracic stick 2 minutes later; Low Power Percussive stun with neck stick followed by thoracic stick 2 minutes later). For each animal, blood samples were taken before stun/slaughter; after stun (if applicable); after neck stick; after thoracic stick (if applicable), and tested for a range of plasma metabolites involved in the stress response; EEG traces were taken by telemetric means throughout the slaughter process and for up to 4 minutes after slaughter; and samples of longissimus dorsi and semitendinosus muscles were taken from the hot carcase, 45 minutes after slaughter, for assessment of meat quality attributes over 2 weeks of storage. The results were analysed by researchers at the Universiti Putra Malaysia.
Outcomes
The results of this study did not indicate significant differences between the slaughter methods in terms of physiological stress or meat quality. The study was carried out at a commercial abattoir and the animals had undergone the normal handling procedures in the lairage. As such, the meat quality and plasma metabolite measurements were confounded by the fact that the animals were already in an 'excited' or 'stressed' state, and therefore the baseline (pre-slaughter) measurements were often already elevated and a further response was not elicited. However, EEG measurements indicated that animals in the unstunned slaughter group were likely to have experienced conscious pain up to 30 seconds post slaughter. They also indicated that penetrative stunning would maximise the possibility of insensibility (i.e. most likely to be effective). Thoracic sticking carried out two minutes after the neck cut did not impart any further benefit on any of the measurements taken. Queries over the efficacy of Low Power Percussive stunning and the impact of ineffective stuns on meat quality, EEG and blood parameters were not addressed in this study – all stunning procedures used resulted in an effective stun.
The outcomes from this study were to be used by the researchers in Malaysia to produce industry guidelines and documentation suitable for submission to the regulatory and religious authorities on the potential use of other stunning methods for the Halal market. Repeating the work under more controlled conditions rather than in a commercial establishment may allow better elicitation of differences between the slaughter methods, as efforts can be made to ensure that the animals are less likely to be excited or stressed at the time of baseline sampling. Furthermore, to address the query over efficacy of low power percussive stunning and the impact of ineffective stuns on meat quality, samples and data should be gathered from animals in a situation where the stuns are not effective.
