Butchering – Slaughtering – Stunning
Reexamination Certificate
2001-05-25
2002-01-15
Little, Willis (Department: 3643)
Butchering
Slaughtering
Stunning
Reexamination Certificate
active
06338673
ABSTRACT:
The present invention relates to apparatus for stunning and/or killing domestic poultry species electrically. The invention is also applicable to the electrical stunning and killing of ostriches. Although ostriches are not strictly speaking poultry, the term “poultry” as used herein will be taken to include ostriches. In some aspects, the invention relates to the handling and electrical stunning/killing of animals in general. The invention, in all its aspects, is particularly suitable for use with broiler chickens.
Current systems for electrically stunning broiler chickens involve the broiler being suspended by its legs on a moving shackle line. The shackles from which the broilers are suspended are electrically grounded; as the broilers proceed along the line, their heads pass through an electrified water bath, thereby completing the electrical circuit between the shackle and the water bath. An electrical current thus flows through the entire bird from its head to its legs. It is necessary for this current to be maintained for several seconds to achieve an effective stun and, therefore, to achieve an acceptable throughput of broilers, it is necessary that a number of the birds are passing through the water bath at any given time; this number will obviously be somewhat variable.
The above system has several problems, one of which is that, with a variable number of birds completing the electrical circuit between the shackle line and water bath at any one time, the current through any individual bird will vary. This results in some cases in an ineffective stun. In order to solve this problem, a system has been developed whereby a constant current passes through each individual bird irrespective of the number of birds passing through the water bath at any one time. The system is described in co-pending international patent applications numbers WO 97/1283 and WO 97/01284, each assigned to the applicant of the present application.
Whilst the system referred to above is very effective in that it ensures that each bird completes a separate electrical circuit, there are still problems with the water bath method of electrocution. The current passing through each bird can still be unpredictable because the path which the current takes is not always predictable; for example one of the birds' wings may touch the surface of the water bath providing an additional current path. The systems in use at the moment also require a relatively high voltage, of the order of 200 volts, and it would be desirable if this could be reduced.
At present, in poultry systems at least, electrical methods are generally used only for stunning. The neck of the stunned bird is then cut and the bird dies through exsanguination. This procedure has been followed for a number of reasons, including the fact that there is a generally held view that the amount of blood draining from the bird's body is increased if the bird's heart is still beating when the neck is cut. It has been determined through experimentation with poultry that, whilst the initial blood flow rate is higher if the heart is beating when the neck is cut, the amount drained is no different if the heart has stopped beating.
A system is currently in use with pigs which involves applying to the head a voltage sufficient to stun the animal and then applying an electrode to the chest to induce a current through the heart to cause death by fibrillation.
This method would be unsuitable for use with poultry because it may have a negative effect on the quality of the breast meat. This problem does not arise in pigs and other red meat animals where the chest area yields very little meat.
The inventors have found, however, that an electrical stun/kill process can be used with poultry by applying the fibrillating voltage using an electrode placed at the rear of the bird rather than on its chest. It is somewhat unexpected that an electrode in this position would produce a flow of current through the heart, and still more surprising that the electrical resistance offered for example between the rear of the bird and its head would be as low as it has been found to be.
It is postulated that the high electrical conductivity of the spinal cord and viscera is in the main responsible for the low electrical resistance of this current path.
The present invention, in its various aspects as detailed below, has one or more of a number of objectives. These include the minimising, preferably to substantially zero, of the possibility of the bird being conscious when its neck is cut. A further objective, which is at least partly connected to the above objective, is to minimise the electrical resistance in an electrical stun and/or kill process and to make this resistance as consistent as possible. Minimising the voltage means that the electrical safety of the system in case of accidental contact by operators is improved. Low voltage requirements also mean that electrical equipment reliability is likely to be improved. Making the resistance consistent means that the current flowing through the bird for a given applied voltage is made as predictable as possible, with consequent reduction of the possibility of any bird not being effectively stunned and/or killed.
Another objective is to allow the humane stunning and/or killing of animals, especially poultry, in a normal position, ie head uppermost. A system has recently been devised (see EP-A-0584142 ) for restraining and conveying poultry such that the bodies of the birds are substantially localised with respect to the moving conveyor and the orientation of the birds is fixed in a predetermined direction. However, no stun/kill apparatus using this conveyor has yet been devised as far as the inventors are aware. It represents a considerable improvement in welfare terms to avoid suspending birds by their legs before they are rendered unconscious.
Another objective of the invention in one or more of its aspects is to provide apparatus and a method for stunning and killing poultry which avoids excessive wing flapping and other movement of the bird during the process. This has advantages in welfare terms and avoids damage to the carcass. In current known systems, dislocated joints, broken wings and other bones, and damage to edible meat are all problems.
A further objective of the invention is the humane restraint of the head and/or neck of animals, particularly poultry, on a conveyor system, to allow for an electrical stun/kill process to be performed on their heads
ecks.
According to a first aspect of the present invention, poultry slaughter apparatus comprises:
(a) a first device for inducing a stunning electrical current to flow through the head of a bird;
(b) a device for applying an electrical voltage between the head and the rear of the bird such that a fatal electrical current passes through the heart of the bird;
(c) restraint means; and
(d) a control system arranged to cause the said first device to commence operating on a given bird restrained by the said restraint means and, simultaneously or subsequently, to cause the said second device to commence operating on the said restrained bird.
It has been found that this apparatus can deliver a slaughtered bird in a short space of time with little or no wing flapping, although the bird may stiffen when the fibrillating current is applied. The slaughtered bird is limp, as compared to conventional systems where the killing stage involving exsanguination, induces “headless chicken” flapping. The apparatus involves the use of relatively low voltages, which consistently produce the desired currents.
The apparatus preferably further comprises a conveyor for conveying restrained poultry to the said stunning and slaughter devices. Most practical commercial slaughter operations, employ an automated moving production line.
The apparatus also preferably comprises a device for locating the bird's head and/or neck to facilitate operation of the first device (stunning device. This may take the form of an elongate track running substantially parallel to the conveyor and space
Berry Paul Simon
O'Callaghan Michael
Raj Ambur Balakrishnan Mohan
Tinker David Bernard
Wilkins Lindsay John
BTG International Limited
Little Willis
Nixon & Vanderhye
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