WO1999051103A1

WO1999051103A1 - Device and method for stunning animals, in particular poultry

Info

Publication number: WO1999051103A1
Application number: PCT/NL1999/000199
Authority: WO
Inventors: Cornelis Meijn; Pieter Meijn; Evert Kikstra
Original assignee: Jm Poultry Technology B.V.
Priority date: 1998-04-06
Filing date: 1999-04-06
Publication date: 1999-10-14
Also published as: AU3174099A; NL1008817C2

Abstract

In a method of stunning animals (3), in particular poultry, at least practically only the head of the animal is exposed to stunning means for efficient stunning of the animal prior to slaughter. The stunning means of the device comprise at least a first and a second electrode (6, 8) which are both situated below a liquid level (10) in a liquid reservoir (4). With the electrodes (6, 8) an electrical current is conducted through the liquid reservoir. By immersing at least the head of the animal in the reservoir, a current will be passed at least through practically only the head whereby the animal is stunned rapidly and efficiently without this resulting in convulsions or other muscle spasms which could adversely affect the meat quality.

Description

-1- Device and method for stunning animals, in particular poultry

The present invention relates to a device for stunning an animal, in particular poultry, comprising a liquid reservoir for receiving therein at least a head of the animal and stunning means intended to act on at least the head of the animal. The invention further relates to a method of stunning an animal, in particular poultry, wherein stunning means act upon at least a head of the animal.

Such a device and method are used here in this country particularly in poultry slaughterhouses wherein birds are first stunned and eventually killed by means of a neck cut. In an existing method and device of the type stated in the preamble the chickens, suspended from their legs, are guided with their head through a water bath. The chickens herein hang from a metal chain which is connected to a first potential, normally earth, while the water bath is maintained at a second, differing potential. As a result of the potential difference applied over the chicken a current flows through the chicken, which results in the intended stunning. This stunning is important for good positioning of the head for the purpose of automatic cutting into the animal so as to cause bleeding of the animal until death occurs. With a view to the welfare of the animals it is important that the stunning is rapid and efficient such that the animal no longer regains consciousness. Animals can thus be prevented from thrashing about wildly, injuring themselves in the slaughter line and suffering unnecessarily.

In order to induce in broilers irreversible termination of brain activity and a cardiac arrest in at least 90% of cases immediately after stunning, an amperage of a minimum of 120 mA is found to be necessary in the case of stunning in a water bath. Although this amperage is to be recommended from the animal welfare viewpoint, such a flow of current results in the existing stunning method in considerable carcass damage and a reduction in meat quality. This loss of quality is the particular consequence of convulsions of the body muscles of the animal which are induced by the current running through the body, this manifesting itself in haemorrhaging in the otherwise wholly white meat, which therefore becomes less attractive and loses value. The present invention has for its object to provide a device and a method of the type stated in the preamble with which animals, and in particular poultry, can be brought into a stunned or, if required, inanimate state in an exceptionally short time, wherein there is no danger, or at least markedly less danger, of convulsions.

In order to achieve the stated objective a device of the type stated in the preamble has the feature according to the invention that the stunning means comprise at least a first and a second electrode which are both arranged in the liquid reservoir, and that at least during operation the electrodes are coupled to a power source so as to conduct an electrical current via the liquid reservoir at least through practically only the head of the animal. For this purpose a method of the type stated in the preamble has the feature according to the invention that at least the head of the animal is carried through an electrically at least lightly conducting liquid reservoir and that an electrical current is conducted via the liquid reservoir at least through practically only the head of the animal.

Other than in the above specified known device and stunning method, in this device and method at least practically no electrical current is conducted through the body of the animal, but only through its head. Convulsions or other muscle spasms as in the known stunning method are thus avoided, which results in an undamaged quality of the final meat. The liquid reservoir herein provides an effective contact surface with the head of the animal.

A particular embodiment of the device according to the invention is characterized in that the liquid reservoir comprises an elongate basin which can be filled to a liquid level with a suitable, electrically at least lightly conducting liquid and that the electrodes comprise two strip-like conductors placed on either side of the basin below the liquid level and extending over at least a large part of the length of the basin. Owing to the elongate configuration the animal can be guided in a fully continuous process between the electrodes, wherein the amperage through the head remains virtually the same and the desired stunning eventually takes place. It is also possible to -3- thus carry and stun more animals simultaneously one after another between the electrodes. In this respect a particular embodiment of the device according to the invention has the feature that the device is provided with transport means for carrying the animal, suspended from the legs, with at least the head through the liquid reservoir along a path extending at least substantially parallel to the first and second electrode.

A further embodiment of the device has the feature according to the invention that at least during operation the electrodes are coupled to an alternating current generator. Although the invention can also be applied with a direct current generator, an AC generator is recommended in practice since herewith not only the amperage but also the frequency thereof can be adapted to an optimum stunning process. It is otherwise noted in this respect that where the present application refers to an alternating current, this is not understood to mean exclusively a purely sinusoidal alternating current, but any form of current with a varying amperage, such as particularly saw-tooth currents and pulsating currents.

For the purpose of fine-adjustment of the stunning process a further embodiment of the device according to the invention has the feature that an output current and frequency of the AC generator are controllable and more particularly that the AC generator comprises a lock-in multistable vibrator with which the form of the alternating current can also be controlled.

In a preferred embodiment the device according to the invention is characterized in that the AC generator is provided with separated current circuits, wherein a primary circuit is connectable to a mains electricity supply and both electrodes are incorporated in a secondary circuit decoupled therefrom. Because the electrodes, and therewith the liquid reservoir, thus receive a floating potential relative to the mains electricity supply, there is no danger of electrocution if someone unexpectedly comes into contact with the liquid reservoir or one of the electrodes, which contributes significantly to the safety of the device. In a preferred embodiment the method according to the invention has the feature that the head of the animal is exposed to an electrical alternating current with a frequency of less than about 500 Hz and an amperage of between about 50 and 150 mA, and more particularly a frequency of between 100 and 200 Hz at an amperage of between 50 and 100 mA. These values have been found in practice to be particularly effective in causing the animal to be completely stunned within a few seconds such that it no longer exhibits any eye reflex although it is still alive. Although the invention can also be used per se to kill the animal, this preferred embodiment has the advantage that the heart of the animal is still beating when a neck cut is applied, thus enhancing bleeding to death of the animal.

The invention will now be further elucidated with reference to an embodiment and a drawing. In the drawing: figure 1 shows a schematic representation of an embodiment of the device according to the invention in which an embodiment of the method according to the invention is applied; and figure 2 is a top view of the slaughtering station of figure 1.

The drawing is otherwise purely schematic and not drawn to scale. Some dimensions in particular are highly exaggerated in the figure. Corresponding parts are designated where possible with the same reference numeral.

The device of figure 1 comprises feed means in the form of a sprocket chain 1 with hanging members 2 from which an animal 3, in this case broilers, can be suspended by the legs. Chain 1 runs in the direction indicated by the arrow over a liquid reservoir 4 filled with mains water 5 or other electrically lightly conducting liquid.

Liquid reservoir 4 comprises an elongate basin which is fillable to a determined liquid level 10. Below this level 10 are situated stunning means in the form of a first electrode 6 and a second electrode 8, which are arranged on both longitudinal sides thereof and extend along practically the whole length of basin 4. The wall of bath 4 is preferably manufactured from a suitable plastic or other electrical insulator so that the danger for the vicinity or of a short-circuit is obviated. Both electrodes 6,8 are both coupled to a current source in the form of an AC generator 20 with which a suitable alternating current can be conducted through the electrodes and the basin. The alternating current preferably comprises, as in this embodiment, two separate circuits, of which a primary circuit 21 is connected to the mains electricity supply and a secondary circuit 22, which is electrically decoupled therefrom, comprises electrodes 6,8. Such a safety power supply avoids an operator being able in unfortunate circumstances to come into contact with a voltage possibly fatal to him.

At the position of bath 4 the chain 1 follows a first bend downward respectively a second bend 7 upward. When chickens 3 reach liquid bath 4,5 they are thus immersed therein with just their head and raised therefrom when leaving the bath. In the bath the head of the chicken thus follows a path extending between both electrodes 6,8 and parallel to their longitudinal direction. Using AC generator 20 a low-frequency alternating current is herein conducted through the bath which will ultimately flow through the head of the animal so as to thus stun the animal quickly and efficiently. Used in this embodiment as alternating current source 20 is a so-called lock-in multistable vibrator with which the amperage, the frequency and the form of the output current can be precisely adjusted. A suitable amperage, frequency and form of current is hereby chosen experimentally in accordance with the size and type of animals such that the animals are completely stunned within a few seconds, which can be verified by the absence of any eye reflex. In practice an amperage of between 50 and 150 mA and a frequency below 500 Hz is found to be adequate for a wide range of animals in achieving the intended objective, wherein a frequency of between 100 and 200 Hz at an amperage of between 50 and 100 mA has been found particularly efficient for broilers.

The animals can thus be brought into a properly stunned condition in relatively relaxed manner without convulsions or other muscle spasms occurring, in which condition the animals are further transported to a slaughter station 30 where by means of a rotating knife 31, see also figure 2, or in other manner an adequate neck cut is performed which kills the animals and allows the blood to drain out. In the further processing an exceptionally fine fillet can thus be obtained from poultry in a fully mechanized slaughterhouse, which fillet is in at least the majority of cases free of blood traces.

Although the invention is further elucidated in the foregoing with reference to only a single embodiment, it will be apparent that in terms of its field of application and modalities the invention is in no way limited to the given embodiment. On the contrary, there are many variations and embodiments which will already occur to the average skilled person without departing from the scope of the invention. The chosen disposition and device, although found to be highly practical and efficient, can thus be replaced by another device for performing of the method according to the invention. Particularly for stunning animals other than broilers, such as small game or other poultry, it is quite well conceivable for the device to be specifically adapted thereto.

A different AC generator can of course be applied than that of the embodiment, wherein for instance the safety provision and/or frequency and voltage control incorporated therein are omitted. Particularly when the slaughter line is always used for the same type of animals, a fixed setting of these parameters can for instance suffice, whereby a cost price reduction can be realized by omitting such controls.

Instead of two electrodes it is also possible to use more electrodes within the route to enable better bridging of the distance from the feed side to the outfeed side of the device. Various aspects will in practice usually be established experimentally in accordance with the specific dimensions and requirements.

Other types of feed means can also be applied within the scope of the invention instead of the shown feed means, even though these are very practical and of a widely used type in practice. Other than in the embodiment, the invention can, if desired, be used for immediate killing of the animals by applying different values of the amperage and frequency of the alternating current which are adapted for this purpose.

The invention generally provides a method and device which allow of very general deployment in at least stunning animals, particularly poultry and more particularly broilers and chickens, in a very effective, efficient and humane manner.

Claims

-8- Claims

1. Device for stunning an animal, in particular poultry, comprising a liquid reservoir for receiving therein at least a head of the animal and stunning means intended to act on at least the head of the animal, characterized in that the stunning means comprise at least a first and a second electrode which are both arranged in the liquid reservoir, and that at least during operation the electrodes are coupled to a power source so as to conduct an electrical current via the liquid reservoir at least through practically only the head of the animal.

2. Device as claimed in claim 1, characterized in that the liquid reservoir comprises an elongate basin which can be filled to a liquid level with a suitable, electrically at least lightly conducting liquid and that the electrodes comprise two strip-like conductors placed on either side of the basin below the liquid level and extending over at least a large part of the length of the basin.

3. Device as claimed in claim 2, characterized in that the device is provided with transport means for carrying the animal, suspended from the legs, with at least the head through the liquid reservoir along a path extending at least substantially parallel to the first and second electrode.

4. Device as claimed in any of the foregoing claims, characterized in that at least during operation the electrodes are coupled to an alternating current generator.

5. Device as claimed in claim 4, characterized in that the AC generator is provided with separated current circuits, wherein a primary circuit is connectable to a mains electricity supply and both electrodes are incorporated in a secondary circuit decoupled therefrom.

6. Device as claimed in claim 4 or 5, characterized in that an output current and frequency of the AC generator are controllable. -9-

7. Device as claimed in claim 6, characterized in that the AC generator comprises a lock-in multistable vibrator.

8. Method of stunning an animal, in particular poultry, wherein stunning means act upon at least a head of the animal, characterized in that at least the head of the animal is carried through an electrically at least lightly conducting liquid reservoir and that via the liquid reservoir an electrical current is conducted at least through practically only the head of the animal.

9. Method as claimed in claim 8, characterized in that an electrical alternating current is conducted through the head of the animal.

10. Method as claimed in claim 9, characterized in that the head of the animal is exposed to an electrical alternating current with a frequency of lower than about 500 Hz and an amperage of between about 50 and 150 mA.

11. Method as claimed in claim 10, characterized in that a frequency of between 100 and 200 Hz is applied at an amperage of between 50 and 100 mA.