The subject matter of the present invention is a method and an apparatus for stunning animals prior to slaughter, in which the animals are introduced into a pit filled with anaesthetic gas prior to slaughter.

In many countries, animals for slaughter must be stunned prior to slaughter for animal welfare reasons. Particularly in the case of larger animals, such as in particular pigs, a method of stunning is known in which the animals to be stunned are conveyed in a gondola through a pit filled with an anaesthetic gas. It is a disadvantage in this case that the design of the pits makes modification of the gas introduction difficult, especially when a different anaesthetic gas is to be used. In addition, the known systems have shortcomings concerning the infeed and supplementary introduction of anaesthetic gas, which becomes necessary in particular as a re sult of entrainment losses due to the movement of the gondolas into the pit and out of it.

Proceeding from this, the present invention has the object of at least partially overcoming the disadvantages known from the prior art.

This object is achieved by a method and by an apparatus having the features of the inde pendent claims. The respective dependent claims are directed to preferred developments.

The method of the invention for stunning animals prior to slaughter, in which the animals are brought from above in a gondola through an opening into a pit having sidewalls and a floor, in which an anaesthetic gas is introduced into the pit, is characterized in that the anaes thetic gas is introduced through at least one gas module which has a gas introduction line fas tened to a support and through which the anaesthetic gas flows, said line having a multitude of pores for introducing the anaesthetic gas into the pit, wherein the support for the at least one gas module is fastened to a sidewall of the pit.

The term "anaesthetic gas" is understood to mean a gas or else gas mixture which in ani mals brings about a loss of consciousness upon inhalation so that these animals do not con sciously experience the slaughtering process. The anaesthetic gas in particular has a density greater than air, so that it remains in the pit purely through the action of gravity. Alternatively, anaesthetic gas has to be continuously introduced as a supplement in order to prevent a drop in the concentration of the anaesthetic gas in the pit, especially a fall below a level that en sures reliable stunning of the animals. In addition, the entry and exit of the gondola(s), which is/are designed as a cage, causes entrainment losses, especially during passage of the gon- dola(s) through the opening, which are compensated during operation by continuous or dis continuous supplying of anaesthetic gas through the at least one gas module. The support is in particular planar, making the gas introduction line overall planar in design. This enables simple preassembly of the gas module and simple fitting. The support is in particular designed as a planar structure, in particular as a planar grid structure. "Planar" is understood here to mean a design in one plane.

The gas introduction line in particular has a multitude of small openings or pores, in par ticular stunning lines are used having for example 1000 openings per metre or more, prefera bly even 3000 openings per metre or more. Anaesthetic gas is fed through these gas introduc tion lines in a laminar flow. This also reduces the stress of the animals for example compared to a turbulent feed of the anaesthetic gas.

The supply of the anaesthetic gas from the side likewise does not further increase the stress of the animals. The modular construction with one or more gas modules facilitates ret rofitting of existing systems and the construction of new systems. The gas modules are preas sembled, all that is then needed on site is to fasten the support for the individual gas modules to a sidewall of the pit.

The gas introduction lines of the individual gas modules each have a supply line which can be connected to a central gas supply, preferably in each case via a control valve. The central gas supply provides the anaesthetic gas preferably at a pressure at a level of at least 1.2 bar, preferably at least 1.7 bar, in particular 2.0 bar or more. This causes the pores in the gas intro duction line to open, since there is a pressure differential of at least 0.2 bar.

Preferably, the anaesthetic gas used is one of the following gases: a) 100% argon (Ar); b) 100% nitrogen (N2); c) a mixture of up to 30% by volume carbon dioxide (CO2), remainder argon (Ar); and d) a mixture of up to 30% by volume carbon dioxide (CO2), remainder nitrogen (N2).

In the case of the pure gases (argon and nitrogen) in particular, the animals are unaware of inhalation of the anaesthetic gas and rapidly become unconscious. This prevents the devel opment of stress in the animals which, is for example triggered by the inhalation of carbon di- oxide in high concentrations. At the same time, the infeed of carbon dioxide achieves a nar cotic effect since the blood pH decreases. At proportions of up to 30% by volume of carbon di oxide, a narcotic effect is achieved without the animals perceiving the inhalation of carbon di oxide. Gentle stunning of the animals can thus be achieved.

Preferably, the gas flows through the gas introduction line of each gas module with a con trollable volume flow. This enables selective control of the concentration of anaesthetic gas in the pit, also for example as a function of the local concentrations of anaesthetic gas at the lo cation of the individual gas module.

Preferably, the design comprises a plurality of gas modules, wherein, during filling of the pit, the gas flows through all gas modules with a predefinable maximum volume flow. This en ables a rapid filling of the pit with the anaesthetic gas at the start of the method, so that there is little setup time prior to commencement of stunning and slaughter.

Preferably, the design comprises a plurality of gas modules, wherein, during passage of the gondola through the opening, the gas flows through the at least one gas module designed nearest to the opening with a controllable volume flow. This enables operation of just the gas modules which are designed nearest to the opening, for example the uppermost gas modules, whereas the other gas modules are not operated. This makes it possible to compensate for losses, especially entrainment losses or diffusion losses, at the locations where they arise (at and through the opening), and reduces the consumption of anaesthetic gas.

In a further aspect of the invention, an apparatus is proposed for stunning animals prior to slaughter, in particular according to the method of the invention, comprising a pit into which the animals can be introduced via a gondola through an opening, wherein the pit com prises sidewalls which delimit the opening and a floor formed opposite the opening, wherein the design comprises at least one gas module, which has a gas introduction line that is fas tened to a support and has a multitude of pores for delivering the anaesthetic gas, wherein the support for the gas module is fastened to a sidewall of the pit.

Preferably, a volume flow through the gas introduction line of each gas module is individ ually controllable. This makes it possible to individually control and regulate the individual gas modules. Preferably, a supply line of each gas module is connected to a central gas supply via a con trol valve such that control of the respective control valve enables regulation of the volume flow through the gas introduction line of the respective gas module.

Preferably, the apparatus also comprises a control device with which each control valve can be controlled. This allows individual control of the volume flow through the individual gas modules.

Preferably, the apparatus also comprises a control device with which the output rate of a central gas supply can be controlled. This can for example be effected by controlling an evapo rator in the central gas supply.

The invention and the associated technical field are elucidated in detail hereinafter with reference to the figures. It should be pointed out that the invention is not intended to be lim ited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract sub-aspects of the subject matter elucidated in the figures and to combine them with other constituents and knowledge from the present description and/or fig ures. In particular, it should be pointed out that the figures and especially the size ratios illus trated are merely schematic. Identical reference numerals denote identical articles, such that any elucidations from other figures can be consulted additionally. In the figures:

Fig. 1 shows a first example of an apparatus for stunning animals;

Fig. 2 shows an example of a gas module;

Fig. 3 shows an example of a cross section of a gas introduction line; and

Fig. 4 shows a second example of an apparatus for stunning animals.

Fig. 1 shows schematically a first example of an apparatus 1 for stunning animals prior to slaughter, comprising a pit 2 into which the animals can be introduced via a gondola 3 through an opening 4, wherein the pit 2 comprises sidewalls 5 which delimit the opening 4 and a floor 6 formed opposite the opening 4 such that the floor 6 is at the bottom in the direction of gravity and the opening 4 is at the top in the direction of gravity. Fig. 1 shows a section through the pit 2 in which three sidewalls 5 are visible. The gondola 3 can - as shown here - be operated as a kind of lift, in which the gondola 3 is passed into the pit 2 from top to bottom, remains in the pit 2 for a defined stunning time and is then drawn back out of the pit 2 from bottom to top. The direction of movement of the gondola 3 is indicated by the arrow 14. Alternatively, the gondola 3 may be part of a paternoster (not shown) having a plurality of gondolas 3 which are moved continuously through the pit 2 such that each gondola 3 remains in the pit 2 for a stun ning time. The chosen stunning time must however be sufficiently long that the animals in the gondola 3 lose consciousness and remain unconscious for a predefinable time that enables the slaughter, for example by cutting the throat, of the animals without the respective animal con sciously experiencing this. After slaughter, the slaughtered animals are processed, in particular opened and cut up.

In order to enable stunning of the animals, the pit 2 must be filled with an anaesthetic gas. In this case, the only losses that need to be compensated result from the entry and exit of the gondola 3 through the opening 4. These losses are referred to as entrainment losses. In particular, if the anaesthetic gas has a density lower than or equal to the density of the sur rounding air, further losses are incurred as a result of diffusion. These are particularly relevant when the anaesthetic gas used is nitrogen with optional admixture of carbon dioxide. Accord ing to the present invention, gas modules 7 perform both the filling of the pit 2 and the com pensation of the losses. The present example shows six gas modules 7.

A gas module 7 is shown in detail in fig. 2 in a perspective view. Each gas module 7 com prises a gas introduction line 8 which is mounted and fixed to a support 9. A gas introduction line 8 is shown in fig. 3 in cross section. The gas introduction line 8 has a multitude of small openings or pores 10 which connect the interior 11 of the gas introduction line 8 to the outside environment of the gas introduction line 8. The gas introduction line 8 is designed here such that, for example, 1000 pores 10 are formed per linear metre of gas introduction line 8.

The gas introduction line 8 of a gas module 7 has a supply line 12 which - together with the supply lines 12 of any other fitted gas modules 7 - is connected to a central gas supply (not shown). Reference in this regard is also made to the discussion below relating to fig. 4. The end 13 of the gas introduction line 8 is closed, which means that the anaesthetic gas in the interior 11 of the gas introduction line 8 is able to exit the gas introduction line 8 exclusively via the pores 10. If the interior 11 of the central gas supply is then pressurized with the anaesthetic gas, anaesthetic gas will exit from the interior 11 into the pit 2 through the pores. As a result of this, the pit is filled with anaesthetic gas or the concentration of the anaesthetic gas is in creased. The anaesthetic gas used here is preferably argon (100% by volume, impurities excepted), nitrogen (100% by volume, impurities excepted)) or a mixture of up to 30% by volume carbon dioxide, the remainder - except for impurities - being argon or nitrogen. At the same time, ar gon and nitrogen in particular have the advantage that they do not trigger any suffocation re flex in the animals and therefore reduce the fear felt by the animals during stunning. At the same time, the modular design of the gas supply via gas modules 7 enables simple equipping of the pit 2 or even retrofitting of an existing pit 2 with a gas supply. The structure made up of a stunning line 8 on a support 9 permits simple and rapid fitting of the preassembled gas mod ules 7, so that retrofitting a pit 2 can proceed rapidly without slaughter downtimes becoming excessive. In the present example, six gas modules 7 are fitted on a sidewall 5 of the pit 2.

As a result of gas modules 7 being fitted on a sidewall 5 (or on a plurality of sidewalls 5) of the pit 2 and the supply through the pores 10 of the gas introduction line 8, the anaesthetic gas is fed laterally into the pit 2 in a laminar flow. When animals are in the pit 2 while the gas module(s) 7 is/are in operation, it has been found that said animals are not additionally fright ened by the infeed of the anaesthetic gas in this way, which means that humane stunning of the animals is possible here without increasing the stress of the animals.

In the present example (cf. fig. 2), the support 9 is designed as a metallic grid structure that is readily fastenable to a sidewall 5 by hanging on hooks or by screw fittings. The gas intro duction line 8 can be fastened thereto for example by hose clips or cable ties. The gas intro duction line 8 is wound in a spiral in this example. This enables a very uniform exit of the an aesthetic gas from the gas module 7. The stunning line 8 used is preferably a perforated plastic pipe with an internal diameter 15 having a defined throughflow volume per linear metre and per hour. This enables standardization of the gas modules 7 in that these are each designed such that in normal operation a defined number of standard cubic metres of anaesthetic gas per metre length per hour can be introduced into the pit 2 per gas module 7. This enables a simple design of the apparatus 1, since the volume of the pit 2 is known. By designing for a de fined number of gas modules 7, it is possible to determine how rapidly the pit 2 can be filled with anaesthetic gas overall and which losses can be compensated. The pits 2 are usually designed so that there is sufficient space available between the gon dola 3 and the sidewalls 5 for the gas modules 7 to be fastened to the sidewall 5 without inter fering with the movement of the gondola(s) 3. This facilitates retrofitting of a corresponding pit 2.

Fig. 4 shows a second example of an apparatus 1 for stunning animals. A preferred variant of the gas supply is to be elucidated using this example. The apparatus 1 is illustrated here only in excerpts; components such as the sidewalls 5, the floor 6 and the gondola 3 are omitted from this figure for reasons of clarity. Reference in this regard is made to the disclosure from fig. 1 to 3 and the description therein.

In this example, the design likewise comprises six gas modules 7 which are fastened to a sidewall but arranged differently than in the first example. In this second example, the six gas modules 7 are arranged in two rows of in each case three gas modules 7, whereas in the first example they are formed in three rows of in each case two gas modules 7. A first gas module 16, a second gas module 17 and third gas module 18 form a first row which is as close as possi ble to the opening 4 of the pit 2, while a fourth gas module 19, a fifth gas module 20 and a sixth gas module 21 form a second row which lies beneath the first row of gas modules 16, 17, 18 and hence further away from the opening 4. The first gas module 16 is connected via its supply line 12 and a first control valve 22 to a central gas supply 23. This comprises, for exam ple, a tank for anaesthetic gas in liquefied form having a corresponding evaporator. Likewise, the second gas module 17 is connected via its supply line 12 and a second control valve 24 to the central gas supply 23, while the third gas module 18 is connected via its supply line 12 and a third control valve 25, the fourth gas module 19 is connected via its supply line 12 and a fourth control valve 26, the fifth gas module 20 is connected via its supply line 12 and a fifth control valve 27 and the sixth gas module 21 is connected via its supply line 12 and a sixth con trol valve 28 to the central gas supply 23. The control valves 22, 24, 25, 26, 27, 28 and the cen tral gas supply 23, in particular an evaporator (not shown) in the central gas supply 23, are connected to a control device 29 via which the flow rate through individual control valves 22, 24, 25, 26, 27, 28 and the output rate of the central gas supply 23 are controlled. The volume flow through the gas introduction lines 8 of each individual gas module 16, 17, 18, 19, 20, 21 can thereby be controlled individually. This makes it possible for the gas to flow through all gas modules 16, 17, 18, 19, 20, 21 at a maximum volume flow, in particular when the pit 2 has to be filled completely with anaesthetic gas at the start and, especially during ongoing operation, for the gas modules 16, 17, 18, 19, 20, 21 to be charged with individual volume flows which are sufficient to compensate for entrainment losses due to the entry and exit of a gondola 3 into/from the pit 2 and possible diffusion losses due to a lower density of the anaesthetic gas compared to the ambient air. Preferably, in this case, only the first gas module 16, the second gas module 17 and the third gas module 18 are charged with individual volume flows of the anaesthetic gas, while the fourth gas module 19, the fifth gas module 20 and the sixth gas module 21 are switched off with no flow passing through them. It is thus preferably possible to compensate for losses such as entrainment and diffusion losses in the vicinity of the opening 4 where they occur. The apparatus 1 preferably comprises one or more sensors 30 via which the concentration of the anaesthetic gas in the pit 2 can be monitored at one or more locations and used as a control variable for controlling the volume flows through the gas modules 16, 17, 18, 19, 20,

21.

The apparatus 1 of the present invention serves to stun animals prior to slaughter, these being introduced with a gondola 3 into a pit 2. On a sidewall 5 of the pit is/are designed a gas module 7, preferably a plurality of gas modules 7. Each gas module 7 comprises a gas introduc tion line 8 having a multitude of pores 10 through which an anaesthetic gas can flow laterally into the pit 2. The multitude of pores 10 ensures a laminar inflow of the anaesthetic gas. The lateral laminar inflow of the anaesthetic gas avoids an increase in the stress of the animals be- ing stunned, thus enabling humane stunning prior to slaughter. At the same time, the modular construction by means of the gas modules 7 facilitates simple dimensioning of the gas intro duction capacities required and also the construction and retrofitting of corresponding appa ratuses 1.

Reference numerals

1 apparatus for stunning animals

2 pit

3 gondola

4 opening

5 sidewall

6 floor

7 gas module

8 gas introduction line

9 support

10 pore

11 interior

12 supply line

13 end

14 arrow

15 internal diameter

16 first gas module

17 second gas module

18 third gas module

19 fourth gas module

20 fifth gas module

21 sixth gas module

22 first control valve

23 central gas supply

24 second control valve

25 third control valve

26 fourth control valve

27 fifth control valve

28 sixth control valve

29 control device

30 sensor