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Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to welfare aspects of the main systems of stunning and killing the main commercial species of animals

doi:10.2903/j.efsa.2004.45
  EFSA Panel on Animal Health and Welfare (AHAW) Acknowledgment The AHAW Panel wishes to thank Dr Mohan Raj, Dr Martin von Wenzlawowicz, Dr Steffen Holst, Dr Claudia Terlouw, Dr. Antonio Velarde Calvo, Dr. Bjorn Roth, Dr. Steve Kestin for the preparation of the Scientific Report and for the contributions to the Scientific Opinion.
Type: Opinion of the Scientific Committee/Scientific Panel Question number: EFSA-Q-2003-093 Adopted: 15 June 2004 Published: 06 July 2004 Last updated: 11 October 2004. This version replaces the previous one/s.
Abstract

No abstract available

Summary

The EFSA Scientific Panel on Animal Health and Welfare was asked by the Commission services to report on the welfare aspects of the main systems of stunning and killing in the main commercial species of animals with consideration of Directive 93/119/EC. Species referred to in the present opinion are: cattle, sheep, pigs, poultry, horses and farmed fish. Welfare aspects of the systems for stunning other species, such as rabbits, deer, ratites or goats, have not been included in the present opinion.

Stunning before slaughter is a statutory requirement in the EU (with exceptions in some Member States for religious slaughter) to induce unconsciousness and insensibility (inability to perceive stimuli) in animals, so that slaughter can be performed without avoidable fear, anxiety, pain, suffering and distress.

This Scientific opinion is a scientific assessment of the welfare during stunning and killing adopted by the EFSA AHAW Panel based on the data of the Scientific Report. In drafting this Scientific Opinion, the panel did not consider ethical, socio-economic, cultural or religious aspects of this topic. Considering the mandate, the present opinion concentrates on the welfare of the animals concerned at the point of application of the stunning and stun / killing techniques and does not consider in detail other preceding or subsequent procedures, although it is recognised that, for instance, transport to the slaughterhouse, lairage conditions, pre-slaughter handling and restraint prior to stunning may cause serious welfare problems. Scientific data on other issues such as food safety, BSE (Bovine Spongiform Encephalopathy), human operator safety, economic impact are not reviewed in this opinion.

This opinion considers the main stunning and stun / killing methods under commercial slaughterhouse and under farm conditions in Europe. Killing of animals without stunning and stun / killing methods for disease control are also considered.

Stunning methods induce temporary loss of consciousness and rely solely on prompt and accurate sticking procedures to facilitate bleeding and to cause death. Sticking involves the severing of major blood vessels e.g. neck cutting or chest sticking. If unbled, even the adequately stunned animal has a potential to regain brain and body functions. Stun / killing methods induce unconsciousness and death either simultaneously or sequentially.

Procedures appropriate to cattle, sheep, pigs, chickens, turkeys, farmed fish and horses and their related minimum requirements such that unconsciousness and insensibility are induced and poor welfare is minimised, are recommended.

An understanding of the states of unconsciousness and insensibility and the measures to assess these permit evaluation of the effectiveness of the different methods applied. Efficient stunning methods disrupt the neurons or neurotransmitter regulatory mechanisms in the brain, causing a long-lasting depolarised neuronal state that renders animals unconscious and insensible. Indeed, most of the known or established stunning methods also induce high degrees of electrical synchronisation in the brain leading to a quiescent or isoelectric electroencephalogram. During and immediately after stunning, depending on the method and species involved, animals show typical behaviour patterns and physical reflexes, which can help to monitor the effectiveness of stunning under commercial conditions. In general, vocalisation in animals during the induction of unconsciousness with any stunning method is indicative of pain or suffering (however, absence of vocalisation does not guarantee absence of pain or suffering). Under practical conditions, eye reflexes and reactions to painful stimuli should always be investigated and evaluated, in combination with the resumption of normal rhythmic breathing and righting reflexes, to assess stunning effectiveness.

The duration of unconsciousness and insensibility varies between methods, species and animals. The stun-stick interval should be sufficiently short to induce death through blood loss before the animal recovers from the stun. Sticking procedures vary between species; however, the supply of oxygenated blood to the brain should be stopped as rapidly as possible.

Stun / killing methods, which induce unconsciousness and death either simultaneously or sequentially, do not rely on bleeding to cause death and therefore should be preferred when available and proven to be effective.

In all the stunning and stun / killing methods (excluding gas mixtures), animals should be restrained appropriately and heads properly presented to the operator for effective application of the procedure(s).

Due to the serious animal welfare concerns associated with slaughter without stunning, pre-cut stunning should always be performed.

As a general rule, each method should be applied only once, i.e. animals should be rendered unconscious and insensible by a stunning or stun / killing method or device applied for the first time. In the event of a failure (unsuccessful stun), the animal should be killed immediately by an appropriate backup killing method.

It is important that all operators involved with stunning and slaughter are competent, properly trained and have a positive attitude towards the welfare of the animals.

All the equipment used for stunning or stun / killing should be maintained in good working conditions and recorded evidence of parameters applied, maintenance and rectified defects should be kept.

There are no ideal methods for the stunning and killing of farm animals for commercial slaughter or disease control purposes and it is therefore necessary to select those procedures whose proper application have most advantages in terms of animal welfare. Bad practice increases the disadvantages of any method.

The penetrating captive bolt, if applied properly, can render sheep and cattle insensible with minimal effects on welfare. Captive bolt usage is appropriate for some pigs, but there can be problems if it is used for boars and old sows. Captive bolt has the disadvantage that there is no automated method for practical use available today and depends essentially on the education and skill of the person who performs the stunning.

Gas stunning has a high potential for humane stunning or stun / killing if non-aversive gases or gas mixtures are used. It requires sophisticated technical equipment. The animals are exposed to a moderate handling stress only.

Electrical stunning can immediately cause unconsciousness and makes the animal insensible. It requires high standards of technical equipment and skilled people to perform and monitor the stun and a system to record the stunning details such as voltage, current and frequency of the current for each individual stun. For automated applications the animal has to be restrained. There is still a lack of knowledge about mechanisms of brain function during application of electrical currents to the head.

There is an urgent need for further detailed investigations of the mechanisms and effects of the different stunning methods, their technical and organisational performance in practice and improved and continuing education of the staff to ensure good animal welfare.

Keywords

cattle, sheep, pigs, poultry, horses, fish, animal welfare, stunning, killing, slaughterhouses, disease control, consciousness, mechanical stunning methods, mechanical stun / killing methods, electrical stunning methods, electrical stun / killing methods, gas stunning methods, gas stun / killing methods, controlled atmospheres, waterjet stun / killing method, microwave irradiation, needle bolts, percussive stunning, mechanical spiking, asphyxia, thermal shock, salt bath, ammonia solution, decapitation, exsanguinations, anaesthesia, slow live chilling, shooting, electric harpoon, barbituric acid derivates, T61, chloral hydrate, magnesium sulphate, potassium chloride, biosecurity.