Method and apparatus for anesthetizing slaughter animals

Abstract

An anesthetization apparatus for anesthetization of slaughter animals prior to slaughter, wherein the anesthetization apparatus comprises: a chamber for accommodating slaughter animals, the chamber having an upper section, a lower section and a transition zone separating the lower section from the upper section, each of the upper section and lower section being shaped and sized to accommodate one or more slaughter animals, the transition zone allowing slaughter animals to be transferred between the upper section and lower section, each section having a proximal end, proximal to the transition zone and a remote end, opposite the proximal end, wherein the upper section and lower section are configured to be filled with respective gas mixtures so as to expose the slaughter animals to different gas mixtures by transferring the slaughter animals between the upper section and lower section, a first circulation system for circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper section and lower section, wherein the first circulation system is configured to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

Description

[0001] Method and apparatus for anesthetizing slaughter animals

[0002] TECHNICAL FIELD

[0003] The present invention relates to an apparatus and a corresponding method for anesthetizing slaughter animals, in particular four-legged slaughter animals, such as hoofed animals, in particular pigs and cattle.

[0004] BACKGROUND

[0005] Awareness of animal well-being is today highly respected e.g. in abattoirs. The purpose of anesthetizing animals is to deprive the animals of pain perception, such as prior to slaughter. The anesthetization procedure should ensure that no animals regain consciousness before, during or after the slaughtering process.

[0006] When anesthetizing animals by gas, there is a progressive loss of consciousness and anesthesia. The process may be described as a succession of stages, starting from an analgesia stage, followed by an excitation stage, an anesthesia stage and finally collapse.

[0007] A frequently used anesthetization method for anesthetizing pigs involves exposure to CO2. For pigs anesthetized with CO2the following can be observed: During the analgesia stage, the pigs are still standing upright; during the excitation stage, pigs are lying down; during the anesthesia stage, pigs still have a corneal reflex, though it disappears in the deep anesthesia; In the collapse stage, the pigs have no reflexes at all.

[0008] Despite previous efforts, there is still a need to further reduce the stress level of animals such as pigs associated with the anesthetization process. In particular, it is desirable to further improve animal well-being in connection with the anesthetization procedure. Moreover, the animal reactions may result in bruises and reduce meat quality. On this background and even though the observed reactions during the initial phases of the anesthetization process only last for a short period of time, it is desirable to reduce these reactions to the extent possible.

[0009] It is further desirable to provide an anesthetization apparatus and process that is efficient and yields a high throughput.

[0010] Yet further, it is desirable to provide a compact system. Yet further, it is desirable to provide a system that can be placed above ground.

[0011] It is also desirable to keep the consumption of gases low.

[0012] WO 2021 / 165279 discloses a method of reducing animal reactions when exposed to a preanesthetizing relaxation gas and / or anesthetizing gas during a pre-anesthetizing and / or anesthetization process, the method comprising: exposing at least one animal to a relaxation gas and / or anesthetizing gas for an exposure period; exposing the at least one animal to at least one smell additive at least during a part of said exposure period, in particular during an initial part of said exposure period. The process may involve exposure of the animals to a relaxation gas in a pre-anesthetizing chamber, followed by movement of the animals into an anesthetizing chamber where they are exposed to an anesthetizing gas. While this method considerably reduces animal reactions, it remains desirable to provide a more efficient method without exposing the slaughter animals to unnecessary stress and without compromising meat quality.

[0013] US6623347 discloses a method and apparatus for producing and maintaining a gas mixture in one or more phases, in which the phases are generated in zones of, for example, a stunning tunnel or a stunning shaft. The gas mixture includes carbon dioxide gas and oxygen gas, and the concentration of air is maintained at a level equivalent to a concentration level in air. Carbon dioxide is added based on the measured level of carbon dioxide in each zone.

[0014] When exposing slaughter animals to a sequence of different gas mixtures by moving the animals between different sections of a chamber, it remains desirable to ensure that uniform gas mixtures are maintained throughout one or more of the sections. It is further desirable to keep the gas mixtures in respective sections of the chamber separate from each other so as to avoid undesired leakage of one gas mixture from one section to another section.

[0015] SUMMARY

[0016] In general, at least some embodiments of the method and apparatus disclosed herein seek to mitigate, alleviate or eliminate one or more of the above-mentioned disadvantages and / or other disadvantages of the prior art, or to at least serve as an alternative to prior art solutions. According to one aspect, disclosed herein are embodiments of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter, wherein the anesthetization apparatus comprises:

[0017] - a chamber for accommodating slaughter animals, the chamber having an upper section, a lower section and a transition zone separating the lower section from the upper section, each of the upper section and lower section being shaped and sized to accommodate one or more slaughter animals, the transition zone allowing one or more slaughter animals to be transferred between the upper section and lower section, each section having a proximal end, proximal to the transition zone and a remote end, opposite the proximal end, wherein the upper section and lower section are configured to be filled with respective gas mixtures so as to expose the slaughter animals to different gas mixtures by transferring the slaughter animals between the upper section and lower section,

[0018] - a first circulation system for circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper section and lower section, wherein the first circulation system is configured to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

[0019] In some embodiments, the anesthetization apparatus is configured to fill one of the sections with a relaxation gas mixture, and the other section with an anesthetization gas mixture, i.e. one of the sections is operable as a stress-reducing section while the other section is operable as anesthetization section. During operation, the slaughter animals may thus initially be positioned in the stress-reducing section of the chamber, where they may be held for a period of time sufficiently long for the slaughter animals to calm down. The slaughter animals may then be transferred into the anesthetization section where the actual anesthetization takes place as the animals are exposed to the anesthetization gas mixture. The transfer between the sections does not involve any long transport, since the animals merely need to cross the transition zone, thereby reducing the risk that the animals are re-agitated again. In particular, the animals are not agitated by being transported from one chamber to another or even pushed or otherwise urged to walk from one chamber to another shortly before the anesthetization process. Accordingly, embodiments of the apparatus described herein reduce or even prevent severe reactions that one may otherwise observe before or during the initial phases of the anesthetization process of animals such as pigs. Accordingly, animal reactions during the anesthetization procedure are reduced, thereby increasing animal well-being and reducing the risk of downgraded meat quality. The provision of a stress-reducing section inside the chamber allows the environment surrounding the animals immediately prior to the actual anesthetization process to be carefully controlled during the stress-reducing process and the animals are not distracted by activities outside the chamber.

[0020] The first one of the upper section and lower section may be either the upper section or the lower section. When the first section is the upper section, the remote end of the first section is the upper end of the upper section and the gas flow within the first section away from the transition zone and towards the remote end of the first section is an upwardly directed gas flow. When the first section is the lower section, the remote end of the first section is the lower end of the lower section and the gas flow within the first section away from the transition zone and towards the remote end of the first section is a downwardly directed gas flow.

[0021] The transition zone separates the lower section from the upper section, i.e. the slaughter animals have to pass the transition zone in order to move or be moved between the upper section and lower section. At least when slaughter animals move or are moved between the upper section and lower section, there is a risk of gas leakage between the upper section and lower section via the transition zone, i.e. a risk that gas flows from the lower section via the transition zone into the upper section and / or that gas flows from the upper section via the transition zone into the lower section. Such gas leakage is undesirable, as it is typically desirable to maintain different gas atmospheres in the respective sections, in particular such that each of the sections has a well-defined gas atmosphere. In each of the section the respective gas atmosphere should preferably be uniform throughout each section.

[0022] Various embodiments of the aspects disclosed herein reduce the risk of such gas leakage or at least reduce the amount of such gas leakage. In particular, this reduces the risk that the animals are prematurely exposed to the anesthetization gas mixture or that the efficiency of the anesthetization is reduced by unintended dilution of the anesthetization gas mixture. Yet further, appropriate gas mixtures may be maintained with relatively small consumption of gas components of the respective gas mixtures. As the circulation system provides a gas flow within the first section away from the transition zone and towards the remote end of the first section, a uniform mixing of the first gas mixture inside the first section is facilitated while reducing gas leakage from the first section to the second section via the transition zone. In some embodiments, the first circulation system comprises a first set of one or more outlet openings at the proximal end of said first section and a first set of one or more inlet openings at the remote end of said first section. Accordingly, the first circulation system may be configured to remove gas from said first section through the first set of inlet openings and to introduce gas into said first section via the first set of outlet openings to create said gas flow within the first section away from the transition zone and towards the remote end of the first section. Accordingly a gas flow away from the transition zone is effectively created within the first section.

[0023] In some embodiments, the first circulation system comprises one or more flow-directing members configured to direct gas flow from the first set of outlet openings along a predetermined direction. In particular the one or more flow-directing members may direct the gas flow out of the openings such that the vertical component of the flow is oriented away from the transition zone and / or such that the horizontal component of the flow is at least predominantly directed away from a sidewall of the chamber and towards a center of the chamber, thereby facilitating the gas flow away from the transition zone and reducing turbulences in the gas flow and / or gas flow towards the transition zone.

[0024] In some embodiments, the apparatus comprises a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and the first circulation system is configured to circulate the first gas mixture responsive to the measured concentration. Accordingly, the gas flow inside the first section may be kept as small as possible while ensuring a uniform first gas mixture across the first section and reducing gas leakage across the transition zone, thereby decreasing the risk of causing discomfort to the slaughter animals.

[0025] In some embodiments, the apparatus comprises an exhaust system configured to remove gas from the transition zone, in particular concurrently with the first circulation system circulating the first gas mixture. The exhaust system may comprise a set of exhaust inlet openings arranged at the transition zone. Accordingly, the risk of gas leakage across the transition zone is further reduced. In some embodiments, the anesthetization apparatus comprises a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and the exhaust system is configured to remove gas from the transition zone responsive to the measured concentration. Accordingly, by controlling the exhaust system based on sensor measurements, gas leakage can be reduced while maintaining a low gas consumption.

[0026] In some embodiments, the apparatus comprises a first filling system for blowing a first gas component of the first gas mixture into the first section. The first filling system may comprise a first set of filling outlet openings located at the remote end of the first section for dispensing the first gas component. Accordingly, the first gas mixture may efficiently be created by adding a suitable gas component to the gas atmosphere already present inside the first section. By placing the filling outlet nozzles at the remote end of the first section, unintended leakage of the gas component being blown into the first section across the transition zone to the second section is reduced.

[0027] In some embodiments, the exhaust system is further configured to remove gas from the transition zone concurrently with the first filling system blowing the first gas component into the first section, thereby facilitating creation of the desired first gas mixture by adding a first gas component to the existing gas atmosphere while further reducing the risk of undesired gas leakage across the transition zone. In particular, when the first gas component is blown in at the remote end of the first section, predominantly the already existing gas atmosphere is extracted by the exhaust system at the transition zone. In this respect, in some embodiments, it may be preferably to stop circulation operation of the first circulation system during the filling process.

[0028] In some embodiments, the anesthetization apparatus further comprises a second circulation system for circulating a second gas mixture of the respective gas mixtures, the second gas mixture occupying a second one of the upper section and lower section, different from the first section. The second circulation system may be configured to create a gas flow within the second section away from the transition zone and towards the remote end of the second section. Accordingly, respective gas mixtures may be maintained in both sections of the chamber, such that the respective gas mixtures are uniformly distributed in the respective section while reducing unintended gas leakage of the respective gas mixtures across the transition zone. The second circulation system may be similar to the first circulation system. In particular, the second circulation system may comprise a second set of one or more outlet openings at the proximal end of said second section and a second set of one or more inlet openings at the remote end of said second section. The second circulation system may thus be configured to remove gas from said second section through the second set of inlet openings and to introduce gas into said second section via the second set of outlet openings to create said gas flow within the second section away from the transition zone and towards the remote end of the second section.

[0029] In some embodiments, the anesthetization apparatus is configured to fill the upper section with an upper gas mixture, in particular a relaxation gas mixture, and the lower section with a lower gas mixture, in particular an anesthetization gas mixture. Accordingly, the upper section may be used as a stress-reducing area for the slaughter animals prior to anesthetization while the lower section may be used as an anesthetization section for anesthetizing the slaughter animals. The slaughter animals may easily be moved from the stress-reducing section into the anesthetization section by lowering them across the transition zone.

[0030] The relaxation gas mixture and the anesthetization gas mixture may conveniently be created in the respective sections. In particular, as mentioned above, the apparatus may be configured to create the upper gas mixture by adding an upper gas component, in particular an upper gas component including a physiologically inert gas such as N2, to the upper section. Alternatively or additionally, the apparatus may be configured to create the lower gas mixture by adding a lower gas component, in particular a lower gas component including CO2, to the lower section. Adding a physiologically inert gas such as N2to the upper section allows the O2concentration in the upper section to be reduced, thus creating a relaxation or stress-reducing gas mixture. Similarly, adding CO2to the lower section efficiently creates an anesthetizing gas mixture in the lower section. As N2has a relatively low specific weight and, in particular lower than CO2, the separation of the upper and lower gas mixtures is further facilitated.

[0031] In some embodiments, the anesthetization apparatus is configured to add the upper gas component through upper filling outlet openings at the upper end of the upper section and to add the lower gas component through lower filling outlet openings at the lower end of the lower section. Accordingly, gas leakage of the added components across the transition zone is reduced. When initially filling the upper section with an upper gas component having a low specific weight, such as N2, this can advantageously be done by blowing the upper gas in at the upper end of the upper section, without the first circulation system operating, thereby pushing the existing gas atmosphere in the upper section downwards towards the transition zone where it can be extracted with minimal mixing. This will require less of the upper gas component to be added for the initial filling as the displaced gas escaping from the transition zone will be almost entirely the existing gas atmosphere, which is typically air, rather than including some of added upper gas component. Once filled, the homogenizing mixing and prevention of mixing with the gas below is preferably done by operating the first circulation system as described herein. Adding the lower gas component to the lower section may be performed in an analogous manner.

[0032] It will generally be appreciated that embodiments of the apparatus may be constructed rather compact, in particular since the separation of the first and second sections from each other may be kept small while still maintaining a good separation of the respective gas mixtures. In particular, the vertical extent of the transition zone may be kept relatively small.

[0033] The transition zone may extend across the entire cross section of the chamber at the interface between the upper section and lower section. The transition zone may be considered as a band or gas layer at the interface between the upper section and lower section where the respective gas mixtures occupying the upper section and lower section, respectively, can mix.

[0034] In an embodiment with circulation systems in both sections, the vertical dimension of the transition zone may be defined by the vertical displacement of the outlet openings of the first and second circulation system. In some embodiments, the first set of outlet openings is vertically displaced from the second set of outlet openings by at least 10 cm, such as at least 20 cm, such as at least 30 cm and / or by no more than 2 m, such as no more than 1 m, such as no more than 60 cm. It will be appreciated that, in addition to being vertically displaced relative to each other the outlet openings of the first and second circulation systems may also be horizontally displaced, i.e. they do not need to be positioned directly above each other.

[0035] In an embodiment having a circulation system only in one of the sections and having an exhaust system at the transition zone, the vertical dimension of the transition zone may be defined as the vertical displacement of the set of outlet openings of the circulation system from the set of exhaust inlet openings of the exhaust system.

[0036] In this respect, the vertical displacement between two openings may be measured as difference in height (i.e. the difference in coordinates relative to a vertical axis) between the centers of respective openings, regardless of whether the two openings are also horizontally displaced. If the openings of at least one of the sets are not all aligned in height within the set, the vertical displacement between the two sets of openings may generally be defined as a largest vertical displacement of the sets, i.e. the vertical displacement of the highest opening of the uppermost set from the lowest opening of the lower set.

[0037] In an embodiment having a circulation system only in the upper section and no exhaust system, the transition zone may be defined as a band or layer spanning across the entire cross section of the chamber immediately below the outlet openings of said circulation system in the upper section, e.g. a band or layer having a height of 10% of the height of the chamber. Similarly, in an embodiment having a circulation system only in the lower section and no exhaust system, the transition zone may be defined as a band or layer spanning across the entire cross section of the chamber immediately above the outlet openings of the circulation system in the lower section, e.g. a band or layer having a height of 10% of the height of the chamber.

[0038] In various embodiments, the exhaust inlet openings are positioned higher than the outlet openings of the circulation system of the lower section and lower than the outlet openings of the circulation system of the upper section. More generally, in some embodiments, the set of exhaust inlet openings is vertically displaced from the first set of outlet openings towards a second section of the upper section and lower section, different from the first section. Accordingly, in some embodiments, the set of exhaust inlet openings is located vertically between the first set of outlet openings and the second set of outlet openings. Again, it will be appreciated that, the exhaust inlet openings may also be horizontally displaced from the outlet openings of the one or more circulation systems.

[0039] Various embodiments of the anesthetization apparatus disclosed herein may be constructed with a small footprint, as the stress-reducing section and the anesthetization section may stack on top of each other or otherwise be positioned at different heights above e.g. a working floor of a slaughter facility. Providing the stress-reducing section and the anesthetization section inside a chamber with the circulation and / or exhaust systems described herein also avoids the need for arranging the anesthetization area in a hole below the working floor of the slaughter facility, because any anesthetizing gases are effectively contained inside the chamber.

[0040] The present disclosure relates to different aspects including the apparatus described above and in the following, corresponding systems, methods, and / or products, each yielding one or more of the benefits and advantages described in connection with one or more of the other aspects, and each having one or more embodiments corresponding to the embodiments described in connection with one or more of the other aspects and / or disclosed in the appended claims.

[0041] In particular, according to another aspect, disclosed herein are embodiments of a method of establishing respective gas mixtures in a lower section and an upper section of a chamber for accommodating one or more slaughter animals to be anesthetized prior to slaughter, wherein the chamber includes the upper section, the lower section and a transition zone separating the lower section from the upper section, each of the upper section and lower section being shaped and sized to accommodate the one or more slaughter animals, the transition zone allowing at least one of the slaughter animals to be transferred between the upper section and lower section, each section having a proximal end, proximal to the transition zone, and a remote end, opposite the proximal end. Embodiments of the method comprise:

[0042] - filling the upper section and lower section with respective gas mixtures, wherein a first one of the upper section and lower section is filled with a first gas mixture;

[0043] - circulating the first gas mixture to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

[0044] According to yet another aspect, disclosed herein are embodiments of a method for anesthetization of slaughter animals prior to slaughter. Various embodiments of the method comprise:

[0045] - providing a chamber for accommodating one or more slaughter animals to be anesthetized prior to slaughter, wherein the chamber includes an upper section, a lower section and a transition zone separating the lower section from the upper section,

[0046] - filling the upper section and lower section with respective gas mixtures, wherein a first one of the upper section and lower section is filled with an anesthetization gas mixture,

[0047] - positioning the slaughter animals into a second one of the upper section and lower section, different from the first section,

[0048] - transferring the slaughter animals from the second section via the transition zone into the first section for anesthetizing the slaughter animals,

[0049] - removing the anesthetized slaughter animals from the chamber, wherein the method further comprises circulating the anesthetization gas mixture to create a gas flow within the first section away from the transition zone and towards the remote end of the first section. Embodiments of any of the methods disclosed herein may be implemented using any of the embodiments of the anesthetization apparatus disclosed herein, or otherwise.

[0050] The various embodiments of the present apparatus and methods may be used for a variety of slaughter animals, in particular four-legged slaughter animals, such as hoofed animals. They are particularly well suited for anesthetizing porcines, bovidae, bovines and / or caprines prior to slaughter.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG. 1 schematically illustrates an embodiment of an anesthetization apparatus.

[0053] FIG. 2 schematically illustrates another embodiment of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter.

[0054] FIGs. 3A-B schematically illustrate different examples of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter.

[0055] FIG. 4 schematically illustrates another embodiment of an anesthetization apparatus.

[0056] FIG. 5 illustrates a more detailed view of an embodiment of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter.

[0057] FIGs. 6A-B schematically illustrate yet another embodiment of an anesthetization apparatus. FIG. 7 schematically illustrates yet another embodiment of an anesthetization apparatus.

[0058] FIG. 8 schematically illustrates another embodiment of an anesthetization apparatus.

[0059] DETAILED DESCRIPTION

[0060] FIG. 1 schematically illustrates an embodiment of an anesthetization apparatus, generally designated by reference numeral 1 , for anesthetizing slaughter animals prior to slaughter.

[0061] The anesthetization apparatus 1 comprises a chamber 100 for accommodating slaughter animals. The chamber 100 may be defined by respective walls delimiting the chamber. The chamber 100 may have one or more openings, configured to allow slaughter animals to be transported into the chamber and / or to be removed from the chamber. The one or more openings may be in the form of one or more doors, gates, roller shutters, fabric doors or other form of barrier that prevents or at least reduces gas flow into and / or out of the chamber, e.g. as described below in connection with FIG. 7. In some embodiments, the barrier has an open state and a closed state and is configured to prevent or at least reduces gas flow into and / or out of the chamber at least when the barrier is in a closed state, and that allows slaughter animals to be moved into or out of the chamber when the barrier is in an open state. The slaughter animals may be transported into the chamber by allowing them to enter the chamber themselves or by transporting them by means of a suitable transport mechanism. Transporting the slaughter animals into and out of the chamber by a suitable transport mechanism allows the anesthetization process to be performed efficiently, as the loading time required for receiving a new group of animals is minimized. Also, as the animals are already on or in the transport mechanism when they are received by the apparatus, the animals have already gotten used to being on or in the transport mechanism and may even have had an opportunity to rest. The animals are not agitated by being pushed or otherwise urged to walk into the chamber shortly before the anesthetization process.

[0062] The chamber 100 has a lower section 110, an upper section 120 and a transition zone 130 separating the lower section from the upper section. Each of the upper section and lower section is shaped and sized to accommodate one or more slaughter animals and the transition zone 130 allows one or more of the slaughter animals to be transferred between the upper section and lower section. In particular, when passing from one section to the other section, the one or more slaughter animals pass through the transition zone. In some embodiments, all slaughter animals accommodated in one section may be transferred to the other section concurrently. In other embodiments, the slaughter animals are transferred one at a time or in smaller groups. The transfer of the slaughter animals may be performed by a suitable transfer mechanism, in particular an elevation mechanism, e.g. as described in connection with FIG. 7 below.

[0063] In some embodiments, the upper section and lower section are not separated by any door or other section divider, whereas in other embodiments, the upper section and lower section may be separated by a section divider, which can selectively be opened and closed to allow the one or more slaughter animals to be transferred between the upper section and lower section.

[0064] Each of the upper section and lower section has a proximal end, proximal to the transition zone 130, and a remote end, opposite the proximal end. The proximal end 111 of the lower section 110 is the upper end of the lower section 110 and the remote end 112 of the lower section 110 is the lower end of the lower section 110. Similarly, the proximal end 121 of the upper section 120 is the lower end of the upper section 120 and the remote end 122 of the upper section 120 is the upper end of the upper section 120. The upper section and lower section are configured to be filled with respective gas mixtures so as to expose the slaughter animals to different gas mixtures by transferring the slaughter animals between the upper section and lower section. Generally, the upper section 120 may be filled with an upper gas mixture and the lower section 110 may be filled with a lower gas mixture. When the upper gas mixture has a specific weight lower than the specific weight of the lower gas mixture, undesired gas leakage between the sections across the transition zone 130 may be reduced.

[0065] In some embodiments, one of the sections, e.g. the upper section 120, includes air, while the other section, e.g. the lower section 110, includes an anesthetization gas mixture. In other embodiments, one of the sections, e.g. the upper section 120, includes a relaxation gas mixture, while the other section, e.g. the lower section 110, includes an anesthetization gas mixture. Accordingly, one of the sections, e.g. the upper section 120, may be operable as a stressreducing section where the slaughter animals are exposed to a stress-reducing environment prior to being transferred into the other section, e.g. the lower section 110, for anesthetization.

[0066] In some embodiments, the anesthetization apparatus is configured to fill the upper section 120 with an upper gas mixture, in particular a relaxation gas mixture, and the lower section with a lower gas mixture, in particular an anesthetization gas mixture. The filling of a section with a gas mixture may be achieved by adding one or more selected gas components to the already existing gas atmosphere, e.g. the existing air, in said section.

[0067] In some embodiments, the anesthetizing gas mixture may include CO2or another anesthetizing gas at a concentration sufficiently high to have a physiological, in particular anesthetic, effect. The balance may be other gases normally present in atmospheric air. The balance may include a major amount of a physiologically inert gas such as nitrogen or argon. The balance may include a minor amount of oxygen and / or other gases normally present in small amounts in atmospheric air. The other gases may have a relative concentration, relative to each other, corresponding to or different from their relative concentrations in atmospheric air. The anesthetization gas mixture may thus be provided in one of the sections, e.g. the lower section 110, by blowing or otherwise dispensing CO2or other anesthetizing gas into said section, such that the added CO2or other anesthetizing gas mixes with the gas atmosphere, in particular the air, which is already present in said section. The concentration of CO2or another anesthetizing gas in the anesthetizing gas mixture may be at least 30 %, such as at least 40 %, such as at least 50 %, such as at least 70 %, such as at least 80 %, such as between 80 % and 90 %. Generally, unless otherwise stated, relative concentrations are intended to refer to relative concentrations by volume. It will be appreciated that the suitable concentration of CO2may depend on the type of animal to be anesthetized. Other examples of gasses to be included in the gas mixture include nitrogen and argon or mixtures thereof, or mixtures of nitrogen and / or argon with CO2.

[0068] The relaxation gas mixture may be selected such that it does not cause anesthetization, i.e. such that the animals are fully conscious and not pre-anesthetized when leaving the stressreducing section, e.g. the upper section, where they are exposed to the relaxation gas mixture. In some embodiments, the relaxation gas mixture is a gas mixture having a low O2concentration, in particular a gas mixture that comprises O2at a concentration below 10 %. The O2concentration is preferably above a minimum level of oxygen concentration, preferably higher than the anesthetic-causing concentration for the animals being processed. The minimum level of the oxygen concentration in the relaxation gas mixture may differ according to animal species, and may be between 3-10 %. Preferably, the oxygen concentration is below 10 % and above 4 %, such as above 5 %, such as above 6 %. Especially for pigs the minimum level of the oxygen concentration of the relaxation gas mixture should preferably be about 6 % to secure the animals are in a reduced stress level and not anesthetized. The relaxation gas mixture may include one or more other gases normally present in atmospheric air, such as nitrogen, argon, carbon dioxide and combinations thereof. The relaxation gas mixture may further include small amounts of other gases, e.g. gases normally present in atmospheric air in small amounts. Preferably, the relaxation gas or gas mixture comprises a major amount of one or more physiologically inert gases such as nitrogen and / or argon and / or xenon. The term physiologically inert gas is intended to refer to any gas being physiological inert for the animals to be treated. In this respect, generally, CO2is not a physiologically inert gas. The anesthetization gas mixture may thus be obtained by adding a physiologically inert gas, such as N2, to the gas atmosphere initially occupying the section, e.g. the upper section, to be filled with the relaxation gas mixture. The gas atmosphere initially occupying the section is typically air or the gas atmosphere remaining in the section after a previous operation of the apparatus. This way, an relaxation gas mixture is obtained in the section to which the physiologically inert gas is added that has a reduced O2concentration, lower than the O2concentration of atmospheric air. In particular, this is obtained without increasing the concentration of any gas component having an anesthetizing effect per se. N2has a specific weight lower than atmospheric air and will tend to concentrate towards the upper end of the section to which it is added. Accordingly when the upper section is filled with a relaxation gas mixture as the upper gas mixture, which has a high concentration of N2or another suitable physiologically inert gas having a low specific weight, the risk that the addition of N2to the upper section causes undesired leakage of N2into the lower section is reduced. In some embodiments, the upper gas mixture thus includes N2at a concentration higher than an N2concentration of air, i.e. at least 79% by volume.

[0069] Accordingly, the upper gas mixture may include a physiological inert gas, such as N2Jat a concentration higher than a concentration of said physiologically inert gas in the lower gas mixture and / or in atmospheric air. The lower gas mixture may include an anesthetizing gas component, such as CO2, at a concentration higher than a concentration of said anesthetizing gas in the upper gas mixture and / or higher than in atmospheric air.

[0070] The apparatus 1 comprises a first circulation system 210 for circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper section and lower section, wherein the first circulation system is configured to create a gas flow 211 within the first section away from the transition zone 130 and towards the remote end of the first section. In the embodiment of FIG. 1 , the first circulation system 210 is for circulating a lower gas mixture that occupies the lower section 110, and the first circulation system 210 is configured to create a downward gas flow 211 within the lower section 110 away from the transition 130 zone and towards the lower end 112 of the lower section 110. It will be appreciated that, in other embodiments, alternatively or additionally to the circulation system for circulating the gas mixture occupying the lower section, the apparatus may comprise a circulation system for circulating an upper gas mixture that occupies the upper section.

[0071] Preferably, the first circulation system 210 further provides a circulation return path 216 through a return conduit or otherwise separated from the first gas mixture occupying the first section 110. Accordingly, inside the first section 110, gas flow towards the transition zone 130 is avoided or at least reduced.

[0072] An embodiment with respective circulation systems in the upper section as well as in the lower section is illustrated in FIG. 2, which schematically illustrates another embodiment of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter. The apparatus 1 of FIG. 2 includes a chamber 100 and a first circulation system 210, where the chamber 100 has a lower section 110, and upper section 120 and a transition zone 130, all as described in connection with FIG. 1.

[0073] The apparatus 1 of FIG. 2 further comprises a second circulation system 220 for circulating a second gas mixture of the respective gas mixtures, the second gas mixture occupying a second one of the upper section and lower section, different from the first section. In the example of FIG. 2, the second section is the upper section 120. The second circulation system 220 is configured to create a gas flow 221 within the second section 120 away from the transition zone 130 and towards the remote end 122 of the second section 120. Accordingly, in the example of FIG. 2, the gas flow 221 is an upwardly directed gas flow within the upper section 120 away from the transition zone 130 and towards the upper end 122 of the upper section 120. Hence, the first and second circulation systems create oppositely directed gas flows in the respective sections that are directed away from each other, thereby suppressing undesired leakage of gas from one section to the other via the transition zone 130.

[0074] Preferably, the second circulation system 220 further provides a circulation return path 222 through a return conduit or otherwise separated from the second gas mixture occupying the second section 120. Accordingly, inside the second section 120, gas flow towards the transition zone 130 is avoided or at least reduced.

[0075] FIGs. 3A-B schematically illustrate different examples of an anesthetization apparatus, generally designated by reference numeral 1 , for anesthetizing slaughter animals prior to slaughter. The examples of FIGs. 3A-B are similar to the embodiment of FIG. 1 , except that the chamber 100 has different shapes.

[0076] While the upper section 110, the lower section 120 and the transition zone 130 of the previous embodiment of FIG.1 are stacked directly vertically above each other and all have the same horizontal cross section, the arrangements of the sections and the transition zone are different in the examples of FIGs. 3A-B. In particular, in the example of FIG. 3A, the chamber 100 has inclined side walls 103. In the example of FIG. 3B, the upper section 110 has a larger lateral extent than the lower section 120. Y1

[0077] Generally, in some embodiments, the chamber 100 has a total height defined between an uppermost ceiling 101 and a lowermost floor 102 of the chamber, and a horizontal cross section which may be defined by the lateral side walls 103 of the chamber. The chamber may have a uniform cross section along its entire height or the cross section may vary, e.g. as in FIG. 3B. For example, one of the sections may be narrower than the other and / or the chamber may have a reduced cross-section at the transition zone, and / or the cross section may vary in another way.

[0078] It will be appreciated that the other embodiments described herein, in particular the embodiments of FIGs. 1 , 2 and 4 - 7, may also have different chamber geometries, e.g. as illustrated in FIGs. 3A-B or otherwise.

[0079] FIG. 4 illustrates another embodiment of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter. The apparatus 1 of FIG. 4 includes a chamber 100, a first circulation system 210 and a second circulation system 220, and the chamber 100 has a lower section 110, and upper section 120 and a transition zone 130, all as described in connection with FIGs. 1 and 2. The apparatus of FIG. 4 differs from the apparatus of FIG. 2 in that the apparatus of FIG. 4 further comprises an exhaust system 300 configured to remove gas from the transition zone 130, in particular by applying suction, as illustrated by arrow 301. The removed gas may be dispensed to the outside environment, optionally after filtering or another cleaning process. In some embodiments, the removed gas may be processed, e.g. so as to separate one or more gas components from the removed gas, such that the separated one or more gas components may be reused, e.g. reintroduced into the chamber. In some embodiments, the exhaust system 300 is operated concurrently with the first circulation system circulating the first gas mixture and / or concurrently with the second circulation system circulating the second gas mixture, thereby further reducing the risk and / or amount of gas leakage from one section into the other across the transition zone 130. Even if gas leaks from one section into the transition zone 130, the leaked gas is at least partly removed from the chamber thereby preventing it from crossing into the other section. It will be appreciated that the embodiment of FIG. 1 may also be provided with an exhaust system.

[0080] FIG. 5 illustrates a more detailed view of an embodiment of an anesthetization apparatus for anesthetizing slaughter animals prior to slaughter. The apparatus of FIG. 5 is similar to the apparatus of FIG. 4 in that it has a chamber 100, first and second circulation systems 210 and 220, respectively, and an exhaust system 300, and the chamber has an upper section 120, a lower section 110 and transition zone 130, all as described in connection with FIG. 4.

[0081] The first circulation system 210 comprises a first set of one or more outlet openings 214 at the proximal end of said first section 110 (i.e. in this example at the upper end of the lower section) and a first set of one or more inlet openings 212 at the remote end of said first section 110 (i.e., in this example, at the lower end of the lower section). The first circulation system 210 is configured to remove gas from said first section 110 through the first set of inlet openings 212, in particular by applying suction, and to introduce gas, in particular to blow gas, into said first section 110 via the first set of outlet openings 214 so as to create the gas flow within the first section 110 away from the transition zone 130 and towards the remote end of the first section 110. The first circulation system 210 may be configured to recirculate the removed gas into the first section, optionally after filtering or cleaning the removed gas, via one or more return conduits 216. The inlet openings 212 may be formed as simple apertures, such as round holes, elongated holes, or as nozzles, or in another suitable manner. Similarly, the outlet openings 214 may be formed as simple apertures, such as round holes, elongated holes, or as nozzles, or in another suitable manner.

[0082] In the embodiment of FIG. 5, the first circulation system includes gas-receiving conduits 211 , in particular pipes, which extend horizontally along respective side walls of the chamber 100 at the remote end of the first section 110, which, in this embodiment, is the bottom end of the lower section 110. The gas-receiving conduits 211 are provided with inlet openings 212 distributed along the gas-receiving conduits 211 . The inlet openings may be provided as apertures in the circumferential wall of the gas-receiving pipes, such as on the portion of the circumference of the gas-receiving pipes that faces the center of the chamber. However, other opening arrangements and / or other forms of gas-receiving conduits may be chosen. For example, the inlet openings 212 may be provided in the side walls of the chamber, or in floor of the chamber, and allow air to be sucked into gas-receiving conduits integrated into the side walls and / or into the floor, or the gas-receiving conduits may be arranged on an outward-facing side of the side walls and / or the floor. Fig. 5 shows two gas-receiving conduits of the first circulation system. However, it will be appreciated that the first circulation system may include a single gasreceiving pipe or other form or conduit or more than two gas-receiving pipes or conduits. For example, inlet openings may be arranged along all four side walls and / or distributed across the floor or otherwise distributed across the remote end of the first section so as to provide suction across the entire remote end.

[0083] Similarly, the first circulation system includes gas-dispensing conduits 213, in particular pipes, which extend horizontally along respective side walls of the chamber at the proximal end of the first section 110, which, in this embodiment is the upper end of the lower section 110. In the example of FIG. 5, the gas-dispensing conduits 213 are arranged adjacent and immediately below the transition zone 130. The gas-dispensing conduits 213 are provided with outlet openings 214 distributed along the gas-dispensing conduits 213. The outlet openings may be provided as holes or slits in the circumferential wall of the gas-dispensing pipes, such as on the portion of the circumference of the gas-dispensing pipes that face towards the center of the chamber and away from the transition zone, i.e. such that the dispensed gas flow leaving the outlet openings has a horizontal velocity component towards the center of the chamber 100 and a vertical velocity component away from the transition zone 130. However, other opening arrangements and / or other forms of gas-dispensing conduits may be chosen. For example, the outlet openings may be provided in the side walls of the chamber, the gas-dispensing conduits may be arranged in the side walls or on an outward-facing side of the side walls. Fig. 5 shows two gas-dispensing conduits of the first circulation system. However, it will be appreciated that the first circulation system may include a single gas-dispensing conduit or more than two gasdispensing conduits. For example, inlet openings may be arranged on all four side walls or otherwise distributed across the proximal end of the first section so as to provide a gas flow away from the transition zone throughout the entire horizontal cross section of the first section 110 or at least throughout a large part of the cross section. The outlet openings may all have the same shape and / or size, or their shape and / or size may vary, e.g. along the length of the gasdispensing conduit, so as to provide a uniform gas flow of the dispensed gas along the gasdispensing conduit. Similarly, the outlet openings 214 may be distributed uniformly or non- uniformly along the gas-dispensing conduit.

[0084] The first circulation system further comprises one or more connecting conduits 216 that fluidly connect the gas-receiving conduits 211 with the gas-dispensing conduits 213. The first circulation system further comprises one or more fans 217, such as one or more blowers, vents or other devices for creating suction at the inlet openings 212 and for creating a gas flow out of the outlet openings 214. The one or more fans 217 may be operationally coupled to the return path of the first circulation system, in particular coupled to the connecting conduits 216. Accordingly, in the embodiment of FIG. 5, the first circulation system 210 sucks gas out of the first section 110 at the remote end of the first section and circulates the extracted gas back into the first section 110 at the proximal end, thereby creating a gas flow within the first section away from the transition zone 130. The connecting conduits 216 thus form a return path of the circulation system 210. In the example of FIG. 5, the first circulation system has two separate return paths, including respective fans, for respective sets of inlet and outlet openings of the first circulation system, thereby facilitating a better control of the gas flow in the first section. However, it will be appreciated, that other embodiments may include a combined return path, optionally with a single fan, while other embodiments may include additional separate return paths and / or additional fans.

[0085] As mentioned in connection with FIG. 4, the first circulation system may optionally comprise additional components such as suitable filters, gas cleaning systems, gas reservoirs, and or the like.

[0086] As illustrated in FIG. 5, the first circulation system may optionally comprise one or more flowdirecting members 215 configured to direct gas flow from the first set of outlet openings 214 along a predetermined direction. In the example of FIG. 5, the flow-directing members are provided in the form of plates radially extending outward from the gas-dispensing conduits in a downward-inward direction relative to the chamber, i.e. along a direction of the desired gas flow out of the outlet openings 214, in particular away from the transition zone. Accordingly, the flowdirecting members 215 facilitate a downward and inward gas flow with respect to the chamber, and prevent gas flow from respective outlet openings to create undesired turbulences, thus facilitating a predominantly laminate gas flow away from the transition zone. In particular, the flow-directing members 215 are operable to guide the gas flow leaving the outlet openings in a radial direction (relative to a longitudinal direction of the gas-dispensing conduit 213) away from the gas-dispensing conduit, thus suppressing any axial flow along the direction of the conduit, which might otherwise cause undesired turbulence. It will be appreciated that other embodiments may include additional or alternative flow-directing members, such as deflecting plates for downwardly deflecting any upwardly directed gas flow from the outlet openings 214. Other examples of flow-directing members include directional outlet openings, such as nozzles, cylindrical flow-directing members, etc. The flow-directing members may be configured to create a gas flow that is uniform across the cross section of the chamber, or that at least are operable to reduce variations of the gas flow across the cross section. The second circulation system 220 is similar to the first circulation system 210 and comprises gas-receiving conduits 221 with a second set of inlet openings 222, gas-dispensing conduits 223 with a second set of outlet openings 224 and fluidly connected to the gas-receiving conduits 221 via connecting conduits 226, all as described in connection with the first circulation system 210, except that the gas-receiving conduits 221 are arranged at the upper end of the upper section 120 and the gas-dispensing conduits 223 are arranged at the lower end of the upper section 120 of the chamber, e.g. immediately above the transition zone 130. Accordingly, the second circulation system 220 is configured to remove gas from a second section, in this case the upper section 120, through the second set of inlet openings 222 and to introduce gas, into the second section 120 via the second set of outlet openings 224 to create the gas flow within the second section away from the transition zone 130 and towards the remote end of the second section 120, i.e. in this case the upper end of the upper section 120. The second circulation system may be configured to recirculate the removed gas into the second section, via connecting conduits 226, optionally after filtering or cleaning the removed gas.

[0087] As was described in connection with the first circulation system, the inlet openings 222 and outlet openings 224 of the second circulation system 220 may be provided in a number of ways. The inlet openings 222 may be provided along, or integrated into, the side walls and / or the ceiling of the chamber. The outlet openings 224 of the second circulation system 220 may be arranged such that the gas flow leaving the outlet openings of the second circulation system has a horizontal velocity component towards the center of the chamber and a vertical velocity component away from the transition zone 130, all as described in connection with the first circulation system. The second circulation system may further comprise one or more fans 227, e.g. one or more blowers, vents or other devices for creating suction at the inlet openings 222 of the second circulation system and for creating a gas flow out of the outlet openings 224 of the second circulation system. The one or more fans 227 may be operationally coupled to the return path of the second circulation system, in particular coupled to the connecting conduits 226. The second circulation system 220 may further comprise flow-directing members 225 configured to direct gas flow from the second set of outlet openings 224 along a predetermined direction, in particular an upward inward direction relative to the chamber. The flow-directing members 225 may thus facilitate an upward and inward gas flow with respect to the chamber, and prevent gas flow from respective outlet openings 224 to create undesired turbulence, thus facilitating a predominantly laminate gas flow away from the transition zone 130. It will be appreciated that other embodiments may include additional or alternative flow-directing members, such as deflecting plates for upwardly deflecting any downwardly directed gas flow from the outlet openings 224 of the second circulation system.

[0088] The first and second circulation systems are preferably fluidly separate systems so as to avoid undesired mixing of the respective gas mixtures in the return paths of the respective circulation systems.

[0089] The first and / or second circulation system is / are preferably configured to create the gas flow, in particular at locations inside the chamber where the slaughter animals are positioned during operation of the apparatus, at a flow speed of less than 3 m / s, such as less than 2 m / s, such as less than 1 m / s. The gas flow may be controlled by controlling the fans 217 and 227 of the circulation systems.

[0090] The exhaust system 300 of the embodiment of FIG. 5 includes gas-receiving conduits 310 having a set of exhaust inlet openings 311. The exhaust inlet openings 311 may be formed as simple apertures, such as round holes, elongated holes, or as nozzles, or in another suitable manner. The exhaust inlet openings 311 are arranged at, preferably within, the transition zone 130 and arranged to extract gas from the transition zone 130. To this end, the gas-receiving conduits 310 of the exhaust system 300 may be arranged along one or more of the side walls of the chamber and have inlet openings horizontally facing towards the center of the transition zone 130. As was described in connection with the first and second circulation systems, the gas-receiving conduits 310 and the exhaust inlet openings 311 may be integrated into the side walls and / or partly arranged along an outward-facing side of the side walls with the exhaust inlet openings extending through the side walls of the chamber. Moreover, the number, arrangement and size of the exhaust inlet openings may be varied. Preferably the exhaust inlet openings are arranged such that gas may be extracted uniformly from the entire transition zone, e.g. by positioning the exhaust inlet openings along the entire circumference of the transition zone, or at least along a major portion of the circumference of the transition zone.

[0091] The exhaust system may further comprise an exhaust fan 320, e.g. a blower, a vent or another suitable device for creating suction at the exhaust inlet openings 311 and for moving the extracted gas out of the chamber, e.g. to a suitable external exhaust outlet 330, to a tank or other exhaust gas reservoir, to an exhaust gas separation station and / or the like. In some embodiments, the anesthetization apparatus 1 comprises a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, e.g. as described in connection with FIG. 8.

[0092] FIGs. 6A-B schematically illustrate another embodiment of an anesthetization apparatus. The apparatus of FIGs. 6A-B is similar to the apparatus of FIG. 4 in that it has a chamber 100, first and second circulation systems 210 and 220, respectively, and an exhaust system 300, wherein the chamber has an upper section 120, a lower section 110 and transition zone 130, all as described in connection with FIG. 4 and / or as described in connection with FIG. 5.

[0093] The apparatus of FIGs. 6Aand 6B further comprises a first filling system 410 for blowing a first gas component of the first gas mixture into the first section 110.

[0094] To this end, the first filling system 410 may receive the first gas component form a suitable first gas reservoir, e.g. from a tank for storing pressurized gas. The first filling system 410 may comprise a first set of filling outlet openings 411 for dispensing the first gas component. The first filling outlet openings 411 are preferably located at the remote end 112 of the first section 110. The first filling system 410 may be completely separate from the first circulation system 210, or it may at least be partially integrated into the first circulation system. For example, the first set of filling outlet openings 411 may be a separate set of openings, different from the inlet or outlet openings of the first circulation system. Alternatively, the first filling system may utilize the inlet openings of the first circulation system, e.g. inlet openings 212 of the embodiment of FIG.5, as filling outlet openings for dispensing the first gas component into the first section 110. To this end, the inlet openings of the first circulation system may be fluidly connected to the first gas reservoir via a first valve and to the outlet openings of the first circulation system via a second valve. During filling of the first section, the first valve may be opened and the second valve may be closed and the fan(s) of the circulation system may be stopped. During operation of the first circulation system, the first valve may be closed, the second valve may be opened and the fan(s) of the circulation system may be operating.

[0095] The apparatus of FIGs. 6A-B further comprises a second filling system 420 for blowing a second gas component of the second gas mixture into the second section 120. To this end, the second filling system 420 may receive the second gas component form a suitable second gas reservoir, e.g. from a tank for storing pressurized gas. The second filling system 420 may comprise a second set of filling outlet openings 421 for dispensing the second gas component. The filling outlet openings 421 are preferably located at the remote end 122 of the second section 120. The second filling system may be completely separate from the second circulation system 220, or it may at least be partially integrated into the second circulation system. For example, the second set of filling outlet 421 openings may be a separate set of openings, different from the inlet openings or outlet openings of the second circulation system. Alternatively, the second filling system may utilize the inlet openings of the second circulation system, e.g. inlet openings 222 of the embodiment of FIG. 5, as filling outlet openings for dispensing the second gas component into the second section 120, e.g. in an analogous manner as was described for the first filling system 410. It will be appreciated that some embodiments may only comprise one filling system, e.g. when one of the sections is filled with air.

[0096] Preferably, the anesthetization apparatus is configured to create a lower gas mixture in the lower section by adding a lower gas component to the lower section where the lower gas component has a specific weight higher than the specific weight of an upper gas component, which is added to the upper section for creating an upper gas mixture in the upper section, and / or wherein the lower gas component has a specific weight higher than the specific weight of the upper gas mixture. As mentioned above, in some embodiments, the lower section is an anesthetization section filled with an anesthetization gas mixture created by adding CO2(or another anesthetization gas component) to the lower section, i.e. to the air or other gas atmosphere already present in the lower section. In such an embodiment, dispensing CO2by the first filling system 410 at the lower end 112 of the lower section 110 reduces the risk that the CO2leaks over into the upper section 120 via the transition zone 130, as the heavier CO2tends to stay at the lower end 112 of the lower section 110. Similarly, in some embodiments, the upper section 120 is a stress-reducing section filled with a relaxation gas mixture created by adding N2by the second filling system to the upper section, i.e. to the air or other gas atmosphere already present in the upper section. This reduces the O2concentration in the upper section. In such an embodiment, dispensing the N2by the second filling system 420 at the upper end 122 of the upper section 120 reduces the risk that the N2leaks over into the lower section 110 via the transition zone 130, as the lighter N2tends to stay at the upper end 112 of the upper section 120. Similar considerations apply when other, relatively light gas components are added to the upper section and / or relatively heavy gas components are added to the lower section. When adding gas components to one or both remote ends 112 and 122, respectively, of the chamber 100 by means of the filling system 410 and / or the filling system 420, the exhaust system 300 may concurrently remove gas from the transition zone 130, i.e. concurrently with the first filling system 410 blowing the first gas component into the first section 110 and / or concurrently with the second filling system 420 blowing the second gas component into the second section 120. When respective gas components are added to both sections, the first and second filling systems are preferably operated concurrently with each other and concurrently with the exhaust system. This way, gas, which is already present in the first and second sections, is displaced towards the transition zone from both sides and extracted from the transition zone by the exhaust system.

[0097] Accordingly gas leakage between sections via the transition zone is avoided and it can further be avoided that that large amounts of the just introduced gas component(s) are extracted again and may go to waste. This is illustrated in FIG. 6A, which illustrates operation of the apparatus during filling of the upper section and lower section with respective gas mixtures. The filling of the sections may be performed prior to slaughter animals entering the chamber or with the slaughter animals already being present in the relaxation section.

[0098] Once appropriate amounts of one or more gas components are added to the respective sections, the filing system may stop inserting gas components and the first and second circulation systems may start operation, so as to provide uniform gas mixtures in both sections while reducing gas leakage across the transition zone 130. The amount of gas components to add may be determined based on a measurement of relevant gas concentrations by suitable gas sensors prior to and / or during dispensing gas components into the sections, e.g. by gas sensors as described in connection with FIG. 8. This is illustrated in FIG. 6B, which illustrates operation of the apparatus during operation of the circulation systems. As explained above, concurrent operation of the exhaust system and the circulation systems further reduces gas leakage across the transition zone 130.

[0099] In some embodiments, once respective and sufficiently uniform gas mixtures are obtained in both sections, the slaughter animals may enter the chamber.

[0100] FIG. 7 schematically illustrates another embodiment of an anesthetization apparatus. The apparatus of FIG. 7 is similar to the apparatus of any of the previous embodiments having one or more circulation systems and an optional exhaust system and optional first and / or second filling systems, all as described above (though not explicitly shown in FIG. 7). The apparatus comprises a chamber 100 having an upper section 120, a lower section 110 and a transition zone 130, also all as described above.

[0101] The embodiment of FIG. 7 further comprises an entrance door 140, an elevation mechanism 150, a section divider 160 and an exit door 170. It will be appreciated that some embodiments may only have some, but not all of these components. For example, some embodiments may lack a section divider and / or only have a single door which serves as an access door as well as an exit door. Yet further, some embodiments may have an exit door and / or an access door in the lower section instead

[0102] Each of the access door 140 and the exit door 170 may be a sliding door, a gate, a curtain, a sectional door, a fabric door, a roller shutter or other form of barrier that prevents or at least reduces gas from leaking out of the chamber, at least when the door is closed.

[0103] Similarly, the section divider 160 may be configured to selectively block passage between the upper section and lower section. To this end, the section divider may be a sliding door, a gate, a sectional door, a fabric door, a roller shutter or other form of barrier that can selectively be opened to allow passage of the elevation mechanism and that prevents or at least reduces gas leakage between the sections when the divider is closed.

[0104] The elevation mechanism 150 may e.g. be a lift, such as a scissor lift, configured to lower the slaughter animals from the upper section 120 to the lower section 110 and to subsequently transport them up into the upper section 120 again.

[0105] During operation, once each section is filled with the desired gas mixture, e.g. as described above with reference to FIGs 6A-B, one or more slaughter animals may enter the upper section 120 via access door 140, which is temporarily opened. Alternatively, the filling of the sections may be performed after the animals have entered the upper section 120. The animals way walk into the upper section or may be transported into the upper section by a suitable transport mechanism, e.g. in a box or cage. The slaughter animals may then remain in the upper section 120 for a certain period of time, where they are in a stress reducing environment, in particular immersed in a relaxation gas mixture as described herein. Accordingly, the upper section serves as a stress-reducing section prior to anesthetization.

[0106] The slaughter animals may then be lowered by the elevation mechanism 150 into the lower section 110 where they are immersed in the anesthetization gas mixture. To this end the section divider 160 may be temporarily opened so as to allow the elevation mechanism 150 with the slaughter animals to pass between the sections via the transition zone.

[0107] After completion of the anesthetization process, the slaughter animals may again be elevated into the upper section 120 and from there transported out of the upper section 120 via exit door 170.

[0108] Preferably, the circulation system(s) operate during the entire process while the slaughter animals are inside the chamber, e.g. as described in the context of any of the previous embodiments.

[0109] FIG. 8 schematically illustrates another embodiment of an anesthetization apparatus. The apparatus of FIG. 8 is similar to the apparatus of any of the previous embodiments having one or more circulation systems 210 and 220, respectively, and an optional exhaust system 300 and optional first and second filling systems 410 and 420, respectively, all as described above. The apparatus comprises a chamber 100 having an upper section 120, a lower section 110 and a transition zone 130, also all as described above.

[0110] The anesthetization apparatus 1 shown in FIG. 8 further comprises a control unit 500, e.g. a controller, a PLC, a suitably programmed computer or the like, which is communicatively coupled to the first and second circulation systems 210 and 220, respectively, to the exhaust system 300 and to the first and second filling systems 410 and 420. The control unit 500 is configured, e.g. suitably programmed, to control operation of the respective systems, e.g. fan speed, the opening or closing of valves and / or the like. It will be appreciated that the control unit 500 may alternatively be implemented as a distributed control unit, e.g. by individual control units of the circulation and / or exhaust systems or even by control units of the individual fans and / or other controllable components of the circulation and / or exhaust systems. The control unit 500 is communicatively coupled to gas concentration sensors 510 configured to measure the concentration of one or more gas components in the upper section and lower section of the chamber, e.g. the O2and CO2concentrations. The control unit 500 may thus be configured to control operation of the various systems based at least in part on the measured gas concentrations.

[0111] For example, the apparatus may detect when the gas mixture in one or both sections deviates from a target range. The apparatus may even include sensors at different locations within one or both of the sections so as to detect how uniform the gas mixtures are within each section. In some embodiments, one or more gas sensors may be positioned within the transition zone 130. It will be appreciated that, in some embodiments, the apparatus may only include a gas sensor in one of the sections.

[0112] Based on the measured gas concentration(s), the control unit 500 may control the first circulation system 210 or the second circulation system 220, e.g. so as to facilitate a better mixing of the individual gas components of the respective gas mixtures and / or so as to control gas flow inside one or both sections away from the transition zone 130. In particular, in some embodiments, the first circulation system 210 and / or the second circulation system 220 is configured to control the removal of gas and / or the introduction of gas from the first section 110 or the second section 120, respectively, responsive to the measured gas concentration.

[0113] Various embodiments may be configured to control the flow rate at which the gas is introduced, e.g. by controlling a fan speed of one or more of the fans and / or by controlling a throttle valve, and / or the like. In some embodiments, the direction of the gas flow may even be controlled, e.g. by providing movable flow-directing members, by providing rotatable gas-dispensing conduits that allow the outlet openings to be selectively oriented in different directions, or the like.

[0114] Alternatively or additionally, the control unit 500 may control the exhaust system 300 based on one or more measured gas concentrations. In particular, in some embodiments, the exhaust system 300 is configured to remove gas from the transition zone 130 responsive to the measured gas concentration. For example, when the apparatus of FIG. 5 is provided with gas sensors and a control unit of the present embodiment, the exhaust system 300 may be controlled based on a measured CO2concentration in the upper section so as to prevent or reduce leakage of CO2from the lower into the upper section. To this end, the control unit 500 may control the sucking strength and / or a direction along which the exhaust inlet openings receive gas from the transition zone. The latter may be controlled by providing the gas-receiving conduits of the exhaust system with repositionable exhaust inlet openings, by movable flowdirecting members and / or the like.

[0115] Generally, various aspects disclosed herein may be summarized as follows:

[0116] Embodiment 1 : An anesthetization apparatus for anesthetization of slaughter animals prior to slaughter, wherein the anesthetization apparatus comprises:

[0117] - a chamber for accommodating slaughter animals, the chamber having an upper section, a lower section and a transition zone separating the lower section from the upper section, each of the upper section and lower section being shaped and sized to accommodate one or more slaughter animals, the transition zone allowing one or more of the slaughter animals to be transferred between the upper section and lower section, each section having a proximal end, proximal to the transition zone and a remote end, opposite the proximal end, wherein the upper section and lower section are configured to be filled with respective gas mixtures so as to expose the slaughter animals to different gas mixtures by transferring the slaughter animals between the upper section and lower section,

[0118] - a first circulation system for circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper section and lower section, wherein the first circulation system is configured to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

[0119] Embodiment 2: The anesthetization apparatus according to embodiment 1 ; wherein the first circulation system comprises a first set of one or more outlet openings at the proximal end of said first section and a first set of one or more inlet openings at the remote end of said first section; wherein the first circulation system is configured to remove gas from said first section through the first set of inlet openings and to introduce gas into said first section via the first set of outlet openings to create said gas flow within the first section away from the transition zone and towards the remote end of the first section.

[0120] Embodiment 3: The anesthetization apparatus according to embodiment 2, wherein the first circulation system is configured to recirculate the removed gas into the first section, optionally after filtering and / or cleaning the removed gas. Embodiment 4: The anesthetization apparatus according to embodiment 2 or 3, wherein the first circulation system comprises one or more flow-directing members configured to direct gas flow from the first set of outlet openings along a predetermined direction, such as away from the transition zone.

[0121] Embodiment 5: The anesthetization apparatus according to any one of the preceding embodiments, comprising a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and wherein the first circulation system is configured to circulate the first gas mixture responsive to the measured concentration.

[0122] Embodiment 6: The anesthetization apparatus according to any one of the preceding embodiments, further comprising an exhaust system configured to remove gas from the transition zone, in particular concurrently with the first circulation system circulating the first gas mixture.

[0123] Embodiment 7: The anesthetization apparatus according to embodiment 6, wherein the exhaust system comprises a set of exhaust inlet openings arranged at the transition zone.

[0124] Embodiment 8: The anesthetization apparatus according to embodiment 7, when directly or indirectly dependent on any one of embodiments 2 through 4, wherein the set of exhaust inlet openings is displaced, at least along a vertical direction, from the first set of outlet openings towards a second section of the upper section and lower section, different from the first section.

[0125] Embodiment 9: The anesthetization apparatus according to any one of embodiments 6 through 8, comprising a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and wherein the exhaust system is configured to remove gas from the transition zone responsive to the measured concentration.

[0126] Embodiment 10: The anesthetization apparatus according to embodiment 9, wherein the exhaust system is configured to control, responsive to the measured concentration, a sucking direction, along which the exhaust system sucks gas from the transition zone into the set of exhaust inlet openings. Embodiment 11 : The anesthetization apparatus according to any one of embodiments 6 through 10, comprising an exhaust gas separation system for separating at least one gas component from the exhaust gas.

[0127] Embodiment 12: The anesthetization apparatus according to any one of the preceding embodiments, wherein the first circulation system is configured to create the gas flow at a flow speed of less than 3 m / s, such as less than 2 m / s, such as less than 1 m / s.

[0128] Embodiment 13: The anesthetization apparatus according to any one of the preceding embodiments, comprising a first filling system for blowing a first gas component of the first gas mixture into the first section.

[0129] Embodiment 14: The anesthetization apparatus according to embodiment 13, wherein the first filling system comprises a first set of filling outlet openings located at the remote end of the first section for dispensing the first gas component.

[0130] Embodiment 15: The anesthetization apparatus according to embodiment 13 or 14, when directly or indirectly dependent on any one of embodiments 6 through 11 , wherein the exhaust system is further configured to remove gas from the transition zone concurrently with the first filling system blowing the first gas component into the first section.

[0131] Embodiment 16: The anesthetization apparatus according to any one of the preceding embodiments, further comprising a second circulation system for circulating a second gas mixture of the respective gas mixtures, the second gas mixture occupying a second one of the upper section and lower section, different from the first section; wherein the second circulation system is configured to create a gas flow within the second section away from the transition zone and towards the remote end of the second section.

[0132] Embodiment 17: The anesthetization apparatus according to embodiment 16, wherein the second circulation system comprises a second set of one or more outlet openings at the proximal end of said second section and a second set of one or more inlet openings at the remote end of said second section; wherein the second circulation system is configured to remove gas from said second section through the second set of inlet openings and to introduce gas into said second section via the second set of outlet openings to create said gas flow within the second section away from the transition zone and towards the remote end of the second section.

[0133] Embodiment 18: The anesthetization apparatus according to embodiment 17, wherein the second circulation system is configured to recirculate the removed gas into the second section, optionally after filtering and / or cleaning the removed gas.

[0134] Embodiment 19: The anesthetization apparatus according to embodiment 17 or 18, wherein the second circulation system comprises one or more flow-directing members configured to direct gas flow from the second set of outlet openings along a predetermined direction, such as away from the transition zone.

[0135] Embodiment 20: The anesthetization apparatus according to any one of embodiments 17 through 19, when directly or indirectly dependent on embodiments 2 and 7, wherein the set of exhaust inlet openings is located vertically between the first set of outlet openings and the second set of outlet openings.

[0136] Embodiment 21 : The anesthetization apparatus according to any one of embodiments 17 through 20, when directly or indirectly dependent on embodiment 2, wherein the first set of outlet openings is vertically displaced from the second set of outlet openings by at least 10 cm, such as at least 20 cm, such as at least 30 cm and / or by no more than 2 m, such as no more than 1 m, such as no more than 60 cm.

[0137] Embodiment 22: The anesthetization apparatus according to any one of embodiments 16 through 21 , comprising a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and wherein the second circulation system is configured to circulate the second gas mixture responsive to the measured concentration.

[0138] Embodiment 23: The anesthetization apparatus according to any one of embodiments 16 through 22, wherein the second circulation system is configured to create the gas flow at a flow speed of less than 3 m / s, such as less than 2 m / s, such as less than 1 m / s. Embodiment 24: The anesthetization apparatus according to any one of the preceding embodiments, configured to fill the upper section with an upper gas mixture, in particular a relaxation gas mixture, and the lower section with a lower gas mixture, in particular an anesthetization gas mixture,

[0139] Embodiment 25: The anesthetization apparatus according to embodiment 24, wherein the upper gas mixture includes a physiologically inert gas, in particular N2, at a concentration higher than a concentration of said physiologically inert gas in the lower gas mixture and / or wherein the lower gas mixture includes a CO2concentration higher than a CO2concentration of the upper gas mixture.

[0140] Embodiment 26: The anesthetization apparatus according embodiment 24 or 25, configured to create the upper and lower gas mixtures by adding an upper gas component, in particular an upper gas component including a physiologically inert gas such as N2, to the upper section and / or a lower gas component, in particular a lower gas component including CO2, to the lower section.

[0141] Embodiment 27: The anesthetization apparatus according to embodiment 26, wherein the upper gas component has a specific weight lower than the lower gas component.

[0142] Embodiment 28: The anesthetization apparatus according to embodiment 26 or 27, configured to add the upper gas component through upper filling outlet openings at the upper end of the upper section and to add the lower gas component through lower filling outlet openings at the lower end of the lower section.

[0143] Embodiment 29: The anesthetization apparatus according to any one of the preceding embodiments, comprising an elevating mechanism for transporting the slaughter animals between the upper and lower section through the transfer zone.

[0144] Embodiment 30: The anesthetization apparatus according to any one of the preceding embodiments, comprising a movable section divider arranged at the transition zone and configured to be selectively brought into a closed state for separating the upper section from the lower section, and into an open state for allowing transfer of the one or more slaughter animals between the upper and lower section. Embodiment 31 : A method of establishing respective gas mixtures in a lower section and an upper section of a chamber for accommodating one or more slaughter animals to be anesthetized prior to slaughter, wherein the chamber includes the upper section, the lower section and a transition zone separating the lower section from the upper section, each of the upper and lower section being shaped and sized to accommodate the one or more slaughter animals, the transition zone allowing at least one of the slaughter animals to be transferred between the upper and lower sections each section having a proximal end, proximal to the transition zone and a remote end, opposite the proximal end,

[0145] - filling the upper and lower section with respective gas mixtures,

[0146] - circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper and lower section, to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

[0147] Embodiment 32: A method for anesthetization of slaughter animals prior to slaughter, wherein the method comprises:

[0148] - providing a chamber for accommodating one or more slaughter animals to be anesthetized prior to slaughter, wherein the chamber includes an upper section, a lower section and a transition zone separating the lower section from the upper section,

[0149] - filling the upper and lower section with respective gas mixtures, wherein a first one of the upper and lower section is filled with an anesthetization gas mixture,

[0150] - positioning the slaughter animals into a second one of the upper and lower sections different from the first section,

[0151] - transferring the slaughter animals from the second section via the transition zone into the first section for anesthetizing the slaughter animals,

[0152] - removing the anesthetized slaughter animals from the chamber, wherein the method further comprises circulating the anesthetization gas mixture to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

[0153] While embodiments of the invention have been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS1 . An anesthetization apparatus for anesthetization of slaughter animals prior to slaughter, wherein the anesthetization apparatus comprises:- a chamber for accommodating slaughter animals, the chamber having an upper section, a lower section and a transition zone separating the lower section from the upper section, each of the upper section and lower section being shaped and sized to accommodate one or more slaughter animals, the transition zone allowing one or more of the slaughter animals to be transferred between the upper section and lower section, each section having a proximal end, proximal to the transition zone and a remote end, opposite the proximal end, wherein the upper section and lower section are configured to be filled with respective gas mixtures so as to expose the slaughter animals to different gas mixtures by transferring the slaughter animals between the upper section and lower section,- a first circulation system for circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper section and lower section, wherein the first circulation system is configured to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

2. The anesthetization apparatus according to claim 1 , wherein the first circulation system comprises a first set of one or more outlet openings at the proximal end of said first section and a first set of one or more inlet openings at the remote end of said first section; wherein the first circulation system is configured to remove gas from said first section through the first set of inlet openings and to introduce gas into said first section via the first set of outlet openings to create said gas flow within the first section away from the transition zone and towards the remote end of the first section.

3. The anesthetization apparatus according to claim 2, wherein the first circulation system comprises one or more flow-directing members configured to direct gas flow from the first set of outlet openings along a predetermined direction, such as away from the transition zone.

4. The anesthetization apparatus according to any one of the preceding claims, comprising a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and wherein the first circulation system is configured to circulate the first gas mixture responsive to the measured concentration.

5. The anesthetization apparatus according to any one of the preceding claims, further comprising an exhaust system configured to remove gas from the transition zone, in particular concurrently with the first circulation system circulating the first gas mixture, in particular an exhaust system comprising a set of exhaust inlet openings arranged at the transition zone.

6. The anesthetization apparatus according to claim 5, comprising a gas sensor for measuring a concentration of one or more gas components of one or more of the gas mixtures in the chamber, and wherein the exhaust system is configured to remove gas from the transition zone responsive to the measured concentration.

7. The anesthetization apparatus according to any one of the preceding claims, comprising a first filling system for blowing a first gas component of the first gas mixture into the first section, in particular a first filling system comprising a first set of filling outlet openings located at the remote end of the first section for dispensing the first gas component.

8. The anesthetization apparatus according to claim 7, when directly or indirectly dependent on claim 5, wherein the exhaust system is further configured to remove gas from the transition zone concurrently with the first filling system blowing the first gas component into the first section.

9. The anesthetization apparatus according to any one of the preceding claims, further comprising a second circulation system for circulating a second gas mixture of the respective gas mixtures, the second gas mixture occupying a second one of the upper section and lower section, different from the first section; wherein the second circulation system is configured to create a gas flow within the second section away from the transition zone and towards the remote end of the second section.

10. The anesthetization apparatus according to claim 9, wherein the second circulation system comprises a second set of one or more outlet openings at the proximal end of said second section and a second set of one or more inlet openings at the remote end of said second section; wherein the second circulation system is configured to remove gas from said second section through the second set of inlet openings and to introduce gas into said second section via the second set of outlet openings to create said gas flow within the second section away from the transition zone and towards the remote end of the second section.

11. The anesthetization apparatus according to any one of the preceding claims, configured to fill the upper section with an upper gas mixture, in particular a relaxation gas mixture, and the lower section with a lower gas mixture, in particular an anesthetization gas mixture,12. The anesthetization apparatus according to claim 11 , configured to create the upper and lower gas mixtures by adding an upper gas component, in particular an upper gas component including a physiologically inert gas such as N2, to the upper section and / or a lower gas component, in particular a lower gas component including CO2, to the lower section.

13. The anesthetization apparatus according to claim 12, configured to add the upper gas component through upper filling outlet openings at the upper end of the upper section and to add the lower gas component through lower filling outlet openings at the lower end of the lower section.

14. A method of establishing respective gas mixtures in a lower section and an upper section of a chamber for accommodating one or more slaughter animals to be anesthetized prior to slaughter, wherein the chamber includes the upper section, the lower section and a transition zone separating the lower section from the upper section, each of the upper section and lower section being shaped and sized to accommodate the one or more slaughter animals, the transition zone allowing at least one of the slaughter animals to be transferred between the upper section and lower section, each section having a proximal end, proximal to the transition zone and a remote end, opposite the proximal end, wherein the method comprises:- filling the upper section and lower section with respective gas mixtures,- circulating a first gas mixture of the respective gas mixtures, the first gas mixture occupying a first one of the upper section and lower section, to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.

15. A method for anesthetization of slaughter animals prior to slaughter, wherein the method comprises:- providing a chamber for accommodating one or more slaughter animals to be anesthetized prior to slaughter, wherein the chamber includes an upper section, a lower section and a transition zone separating the lower section from the upper section,- filling the upper section and lower section with respective gas mixtures, wherein a first one of the upper section and lower section is filled with an anesthetization gas mixture,- positioning the slaughter animals into a second one of the upper section and lower section, different from the first section,- transferring the slaughter animals from the second section via the transition zone into the first section for anesthetizing the slaughter animals, - removing the anesthetized slaughter animals from the chamber, wherein the method further comprises circulating the anesthetization gas mixture to create a gas flow within the first section away from the transition zone and towards the remote end of the first section.