«October 2009 SCIENTIFIC COORDINATOR Pierre Le Neindre, Senior research scientist, INRA (French National Institute for Agricultural Research) ...»
As far as we know, no study has examined the genetic impact of breeding programmes for beef cattle on aggressive or deviant behaviours. There is reasonable genetic variability for ease of handling and docility. This could have implications not only for the safety of the stockbreeders but also for the frequency of the incidents during handling and therefore on painful events. However no experimental proof yet supports this hypothesis.
4.5. Known or potential sources of pain associated with slaughtering
In France there are about 64 commercial poultry abattoirs and 340 large animal abattoirs of which some are specialised (29 for pork; 9 for adult cattle and 2 for calves). The number of abattoirs has fallen in recent years.
About a third of these slaughterhouses are licensed to carry out Halal and Shechita ritual slaughter.
4.5.1. The regulatory framework for slaughtering The slaughter of commercial animals destined for consumption is regulated by articles R214-63 and R214-72 of the rural law code. We will refer here only to some particularly important points. First, the fact that the measures
provided by these articles are not applied in three specific cases:
• technical and scientific experiments which are under the control of veterinary services,
• animals put to death during cultural or sporting occasions,
• game killed in the course of hunting (see article R214-63).
All stages of the slaughter process are covered, starting with transportation and including lairage at the abattoir, immobilization, stunning and finally killing/ slaughtering the animal (note that slaughtering corresponds to causing the death of animals by bleeding). Article R214-67 points out that all sites, installations, and equipment of abattoirs must be designed, constructed, maintained and used so as to spare the animals any avoidable stress, pain and suffering.
Expertise scientifique collective "Douleurs animales" 67 Among the most important stages of the process is the stunning of the animals which is compulsory before
slaughtering or killing, except in three cases:
• ritual slaughter,
• putting farmed game to death when the killing method leads to immediate death. The techniques for killing animals without bleeding them are only permitted for small farmed, feathered game and for fowl for recognised traditional culinary usage (article R214-72).
• putting animals to death as a matter of great urgency/ emergency slaughter (article R214-70).
For ritual slaughter, special measures are fixed by the rural law code (articles R214-73 to R214-75) which point out that it is mandatory for ritual slaughter to take place in an abattoir, after mechanical immobilization for sheep, goats and cattle both before and during bleeding. It must, by definition, be carried out by a sacrificer authorized by the recognised religious organisations.
For killing or slaughtering animals outside of slaughterhouses, special rules are fixed by articles R214-77 and 78 of the rural law code and concern only the following cases: the fight against infectious diseases, dangerous or potentially dangerous animals, animals bred for their fur, chickens and embryos that are eliminated at the hatchery level, or certain big farmed game slaughtered or put to death on the farms where they are reared and where hunting is allowed.
The measures for slaughter or killing animals as part of a biosecurity process (for example outbreaks of certain epizootic of diseases), are regulated and will not be covered in this review. The killing conditions are defined only for animals with fur and chickens and embryos eliminated at the hatchery level. In addition, euthanasia of animals on the farm by stockbreeders is a currently debated topic (see Chapter 5). We have practically no data on the number of animals put to death on farms by stockbreeders or the conditions under which this is carried out, except for the particular case in rabbits where one study notes that about 7 % of young rabbits are eliminated by farmers at birth. It seems that this type of euthanasia is also practised in certain cases by pig farmers but no data are available. This situation has led the Veterinary Academy of France to suggest that this practice be tolerated in particular situations and under precise conditions of practice and regulation.
4.5.2 Pain associated with slaughter of farmed animals The period prior to slaughter This period consists of loading the animals at the farm, transport to the abattoir (with or without passing through a sale-yard), unloading at the abattoir and holding them in lairage until it is time to lead them to the stunning area.
This period is complicated with several factors that could potentially cause pain. Handling procedures and aggressive interactions between animals are the most frequent reasons for animals having pain. Many steps have been taken by the industry in this domain. The first is the training of the persons associated with transport and handling. The design of trucks has been overhauled and the transport fleet has been improved to a great extent.
Handling yards have also been improved considerably to avoid mixing young cattle, to facilitate the movement of animals and to minimize risks for both them and the handlers. It should be pointed out that these improvements concern not only animals being sent to abattoirs but are equally applicable to animals that are transported long distances to change farms. In particular this concerns cattle from dairy herds intended for fattening (young bulls fattened in Italy for instance).
Poultry are gathered either manually or mechanically (see section 4.2.2.) and transported to the abattoir. At the abattoir, when stunning by electronarcosis is in use, the bird is hung upside down by the legs and moved, head down, to an electrified bath. This technique is probably painful, especially if the shackle size is badly adapted to the size of the legs.
Ruminants have to be moved from the lairage area at the abattoir to the stunning box. The most frequently used methods to encourage forward movement of the animals through the facilities comprise not only vocal means, but also include prodding with sticks and electric goads, both of which cause pain. A recent study showed that more than 97 % of carcasses of large cattle had contusions, some due to blows with a stick, but also because the animals bash against barriers when being moved or due to fighting among themselves. The frequency and degree 68 Expertise scientifique collective "Douleurs animales" of contusions are a function of the density of the animals in trucks, whether or not they have been through a saleyard and the quality of roads and conditions during transport. In the abattoir, these contusions may be due to poorly designed or unsuitable equipment in the raceways and the stunning box (absence of devices for head restraint, swinging rails and anti back-up devices). In slaughter calves, sliding and falling, linked to their being frightened or having spent a long time in transport and waiting at the abattoir, also cause contusions and potential pain.
In pigs, a common practice is to mix several rearing pens of animals together for transport and this leads to fighting between animals, resulting in lesions and wounds.
In fish, the preparation for slaughter requires the animals to be grouped. They are either slaughtered next to the rearing pond, transported a short distance to a slaughter room at the breeding site, or transported over a distance of variable length to a specialized abattoir. All of this requires that the fish be removed from their normal environment and often exposes them to air. At the moment we do not know if exposure of fish to air causes nociception. Nevertheless, harvesting the fish in big nets constrains them and can damage scales or gills, and is a potential source of nociception. Different techniques for loading fish are used depending on the species (by pump, fishnet, or conveyor belt). Harvesting and loading result in hormonal changes and behavioural responses that are more or less marked according to the species and the conditions. These responses vary according to the techniques used.
Stunning Except under exemption, pre-slaughter stunning (either reversible or not) is mandatory. The objective of stunning is to induce rapidly an unconscious state that lasts long enough so as the animal does not regain consciousness during bleeding. The technique itself should not cause pain. The method of choice depends in general on the species. Depending on how the technique is implemented, it may induce psychological stress due to isolation or unfamiliarity with the environment. The main techniques used are: electronarcosis, the captive bolt and stunning by gas.
Bearing in mind the signs covered in Chapter 3 under the heading of slaughter, the source or sources of pain at each of the stages of stunning and/or bleeding were evaluated on the basis of the time taken for the animal to lose consciousness. We will discuss unconsciousness rather than pain, because the state of unconsciousness guarantees the absence of pain.
By passing a current through the brain, electronarcosis (or electrical stunning) consists of inducing a synchronized discharge of the neurones (epileptiform EEG). These neurones no longer function properly until they are repolarised. In addition, the electronarcosis causes a release of glutamate and aspartate in the brain which are also partly responsible for the loss of consciousness. Depending on the species (pig, cattle or sheep), and according to the age of the animal, "head only" electronarcosis causes epileptiform waves for 25 [±2] seconds in calves, (250 Volts for 3 seconds), or for 65 [±3] seconds in sheep (200 Volts for 3 seconds). We often see a tonic stage then a stage of more or less regular contractions (clonic), of variable length according to species. The main behavioural sign of lack of consciousness is the absence of a corneal reflex, which reappears before the clonic stage in sheep, and after it in pigs and calves. If a third electrode is put on the breast ("head-body" electronarcosis), it leads to cardiac fibrillation. Preliminary studies show that "head-body" electronarcosis causes cardiac fibrillation that extends unconsciousness and often results in the death of the animal by cardiac arrest. "Head-body" electronarcosis therefore seems to augment, in most species, the effectiveness of electronarcosis (unconsiousness in 24 [±12] seconds in sheep), but these results are yet to be confirmed.
In France, electronarcosis is used principally for pigs, sheep and poultry. Electronarcosis has the advantage of having an instantaneous effect and being employable for all species. One of the major disadvantages of electronarcosis, especially when it is automated, is associated with poor handling and difficulties in positioning the electrodes and adjusting the settings. If wrongly used electronarcosis can stimulate pain receptors and cause pain without inducing unconsciousness. Depending on the abattoir, the quality of the equipment and the size and shape of the animals, the amount of current passed can be insufficient and painful. Thus, a New Zealand study in 2001 reported extreme values of percentages of unsatisfactory electronarcoses varying from 2 to 54 % in sheep depending on the circumstances.
In these animals, the presence of wool might have contributed to the ineffectual electronarcoses.
Expertise scientifique collective "Douleurs animales" 69 The second technology for stunning is the captive bolt. The bolt can be penetrating (the most commonly used which produces mechanical tissue damage) or not penetrating. In both cases, the technique produces a percussion, or, in other words, jolts the brain within the skull causing axonal damage. The captive bolt also produces considerable lesions on the skull and in the brain. It can be a reliable and very efficient way of inducing an instantaneous and lasting loss of consciousness. However, in practice, and depending on the type of animal, failure rates may range from 6 to 16 % in cattle at commercial abattoirs, and therefore there is a risk of pain.
The third technology is stunning by gas. This comprises immersing the animal in a mixture of gasses, often containing a high concentration of CO2; in general 40 % for poultry and at least 70 % for pigs. Other systems use argon and nitrogen. The behavioural responses of the animals, notably agitation and the attempts to escape, strongly suggest that the perception of this gas is unpleasant, or even painful. In poultry, the addition of oxygen reduces the adverse reactions. The time taken to induce loss of consciousness varies with gas concentration, but is around 17 seconds for the pig (collapse of the animal) and from 32 to 34 seconds for poultry (closing of the eyes). The technique is widely used in some countries of Northern Europe. In France, several pig abattoirs have recently been equipped with this system (cf. Chapter 5).
Bleeding The objectives of bleeding are to cause death of the animal and drain the blood from the carcass. There are two choices of incision site from which cattle and sheep can be bled: the throat (severing both carotid arteries and both jugular veins) or the thorax. For the latter in cattle, the jugular groove is first cut at the base of the neck. In sheep and pigs, thoracic bleeding is done with a single stroke. Persisting unconsciousness and death result probably from the lack of oxygen due to reduction in arterial pressure and the absence of breathing.
In calves and adult cattle, the effectiveness of bleeding from the throat is very variable. This variability is explained by the formation of blood clots, which appears to be related to the retraction of the artery within its connective tissue sheath. Impaired blood flow is reported in some studies to occur comparatively often (in up to 16 % of adult cattle and 25 % of calves). It is especially a problem if the stunning is reversible (electronarcosis) or in slaughter without pre-stunning (special case of ritual slaughter, see below). It postpones the death of the animal and can result in its regaining consciousness in the case of reversible unconsciousness. In general, thoracic bleeding is more efficient than bleeding from the throat as it allows better blood flow, but it takes longer and is trickier to perform in adult cattle so can only be used if the animal is stunned.
Unilateral bleeding gives poorer results in pigs and poultry than bilateral bleeding.