Method and system for reducing methane production in ruminant animals

Abstract

The invention relates to a method and system for supplying drinking water with added methane reducer to animals, where a concentration of the methane reducer is measured and the amount of methane reducer that is added to the water is adjusted based on the measured concentration.

Description

[0001] DSM IP Assets B.V. 34806-WO-PCT

[0002] Method and system for reducing methane production in ruminant animals

[0003] Field of the invention

[0004] The present invention relates to methods and systems that allow reducing methane production in ruminant animals.

[0005] Background of the invention

[0006] Ruminants (e.g., cattle, sheep, goats) produce methane during digestion due to microbial activity in the rumen. Methane is a potent greenhouse gas, and reducing its emission is critical for environmental sustainability. Several existing methods target methane reduction, such as adding feed additives like 3-nitrooxypropanol (3-NOP), which have shown success but come with challenges such as inconsistent dosing and risks of toxicity.

[0007] Feeding animals using lick blocks or dry feed supplementation can lead to inconsistent intake, where dominant animals may overconsume while others underconsume. Against this background, WO 2022 / 221925 A1 proposes a solution by administering methane reducers (e.g., 3-NOP) in the animals' drinking water. This ensures uniform dosing, as water intake is generally proportional to the animals' body weight. The addition amount of the methane reducer is determined based on a prediction of water intake of the animals under certain conditions and controlled through specific dosing units. There is no determination of the actual concentration of the methane reducer in the drinking troughs, however, which makes the method prone to error. For example, water evaporation from drinking troughs may have an unpredictable influence, especially in warm regions. Hence, there is a risk of both health issues due to overdosing and reduced methane inhibition due to underdosing.

[0008] Summary of the invention

[0009] The present invention aims to address these issues and, against this background, proposes a method and system that allows controlling the addition amount of the methane reducer based on measurement of the actual concentration downstream the dosing unit.

[0010] Specifically, a method of the invention comprises the following steps: supplying drinking water to at least one watering point for animals; adding a methane reducer to the water using a dosing unit; measuring a concentration of the methane reducer downstream the dosing unit using a sensing unit; adjusting the amount of methane reducer that is added to the water based on the measured concentration. A system of the invention comprises: a drinking water system for animals including at least one watering point and configured for supplying water to the watering point; a dosing unit that is configured to add a controllable amount of a methane reducer to the water that is supplied to the watering point; a sensing unit configured to measure the concentration of methane reducer downstream the dosing unit; a control unit connected to the sensing unit and the dosing unit and configured to adjust the amount of methane reducer that is added to the water based on the measured concentration.

[0011] Detailed description of the invention

[0012] The watering point(s) are preferably drinking trough(s), but can comprise other watering points that are used in farming, like bowl drinkers or nipple waterers.

[0013] In an embodiment, the sensing unit is arranged at the watering point. In another embodiment, the sensing unit can be arranged at a line for supplying the drinking water to the watering point. Along the line, the measurement can take place in proximity, for example within 5 meters, of the dosing unit, or further downstream.

[0014] The sensing unit preferably comprises an electrochemical sensor. Such sensor has high sensitivity and selectivity towards many potent methane reducers. For example, over reducing the nitrooxy-group of 3-NOP at a characteristic potential, the sensor can accurately determine a concentration of 3-NOP even in the presence of potential interferants.

[0015] The electrochemical sensor can be designed as a three-electrode system (working, reference, and counter electrodes) or a simpler two-electrode system. The three-electrode system can be preferred for greater accuracy. The sensing can be based on cyclic voltammetry, amperometry, potentiometry, and impedance spectroscopy. Cyclic voltammetry can be preferred in some embodiments.

[0016] In an embodiment, the working electrode of the electrochemical sensor is a carbon-based electrode, such as a screen-printed carbon electrode (SPCE), a glassy carbon electrode (GCE), or a modified carbon nanotube (CNT)-based electrode.

[0017] In an embodiment, surface modification is used on the working electrode to achieve higher sensitivity, better selectivity, and faster response times. Useful modifications in this context comprise metal nanoparticles, such as Au, Ag or Pt nanoparticles, metal oxide nanoparticles, such as TiC>2, ZnO or MnC>2 nanoparticles, carbon-based nanomaterials, such as graphene or carbon nanotubes, conducting polymers, such as polypyrrole (PPy), polyaniline (PANI) or poly(3,4-ethylenedioxythiophene) (PEDOT), metal-polymer or metal-carbon nanocomposites, such as gold-graphene nanocomposites, ionic liquids, molecularly imprinted polymers, enzyme, antibody or other biological modifications, and combinations thereof.

[0018] The reference electrode can preferably comprise silver or silver chloride. The counter electrode can be carbon or noble metal, for example.

[0019] The sensing unit and, specifically, the electrochemical sensor is preferably reusable and used for multiple measurements or ongoing monitoring over a longer period of time. For that purpose, it is advantageous that the sensing unit undergoes a cleaning protocol after each use or measurement, after a certain time, after a certain number of measurements, in response to a certain condition, or the like. The cleaning protocol can be configured to remove any residual analyte (methane reducer) or interferents from the sensor surface. The electrode materials and surface modifications are preferably made such that they can withstand multiple cycles of use and cleaning.

[0020] The sensor can be pre-calibrated for certain analytes (methane reducers) with standards and real samples. Calibration curves that relate the electrochemical signal to the concentration of the analytes can be stored in the sensor electronics. The sensor can also be self-calibrating for measurement range and offset selection to improve measurement accuracy.

[0021] The measurement can be continuous real-time monitoring, or can comprise monitoring in certain predetermined time intervals.

[0022] The measurement can take place directly at the pipe or watering point or use water that has been removed from the pipe or watering point over, for example, a drain or in a bypass. Using water that is diverted or removed from the pipe or watering point can be advantageous to avoid any potential pollution of the drinking water by electrode materials, components on the electrode surface, or reaction products from electrochemical conversion.

[0023] The sensing unit can be permanently associated with the point of measurement, or can be integrated in a portable device. Connection with the control unit can be over cable or wireless, with any suitable protocol known in the art. In preferred embodiments, the methane reducer can be selected from 3-NOP, bromoform, and nitrate. 3-NOP and bromoform are methyl-coenzyme M reductase (MCR) inhibitors. MCR is an enzyme that catalyses the final step of the methanogenesis pathway from an intermediate compound, methyl-CoM, to methane, and so inhibition of MCR inhibits methanogenesis. Nitrates act as hydrogen sinks in the rumen, competing with methanogens for available hydrogen, which indirectly reduces methane production. This prevents the methanogens from producing methane by reducing the available hydrogen needed for the MCR reaction.

[0024] In an embodiment, the method and system can also include a dispenser that is configured to add a controllable amount of one or more further supplements to the water that is supplied to the watering point. Further supplements can include, for example, a copper salt like copper(ll) sulphate for preventing copper deficiency in areas where soil or forage is deficient in copper. An electrochemical sensor of the sensing unit can also sense such elements, which can undergo reduction, like 3-NOP, or oxidation, with high sensitivity and selectivity. Hence, in a system and method of the invention, controlled addition of the further supplement can, like addition of the methane reducer, be controlled based on the actual concentration of the further supplement downstream the respective dosing unit.

[0025] Brief description of the figures

[0026] Further details and advantages of the present invention will be explained in the following, with reference to figures and examples. The figures show:

[0027] Fig. 1 : a schematic illustration of a water distribution system for animal farming, configured according to the present invention;

[0028] Fig. 2: a schematic illustration of an electrochemical sensor as used in the context of the present invention; and

[0029] Fig. 3: a flow diagram for a method of the invention, according to embodiments.

[0030] Exemplary embodiments

[0031] A water distribution system 100 for animal farming is schematically illustrated in Fig. 1. The system comprises a primary water source 11 , such as a well, reservoir, pond, or municipal water supply. The source should provide clean, fresh water with sufficient capacity to meet the daily needs of the herd. A large-capacity water storage tank 12, which can be formed, for example, from metal or plastic, is used to hold water drawn from the primary source 11. This tank 12 ensures a stable supply and can be refilled either automatically or manually. It can be placed in a shaded area to prevent overheating of water in hot climates. The tank 12 should be sized according to the number of animals. For instance, a storage capacity that meets the requirement of 45-60 liters per cow per day is typical, with adjustments for hotter climates or lactating animals (which usually need 30% more water). The system 100 can include filtration units to remove debris, contaminants, and pathogens from the water, ensuring that animals are drinking clean water. Water can continuously be monitored for parameters like pH and temperature. A UV sterilization system or chlorination can be added for additional disinfection, especially if the water source 11 is prone to contamination.

[0032] A network of pipes 13 connects the storage tank 12 to watering points 14. These pipes should be durable and resistant to weather conditions, and can be made of polymers, like PVC or polyethylene, or metal. The pipes 13 are routed to ensure that water is delivered efficiently to multiple watering points 14.

[0033] The watering points 14 are the points where animals access water. Different options are possible, depending on the farm size and infrastructure. A common option are drinking troughs, which can be fitted with float valves to maintain a consistent water level. The troughs can be placed in easily accessible areas within the grazing field. As an alternative, for example, automatic waterers can be used as watering points 14. These are self-filling water bowls that release water as the animal drinks.

[0034] According to the invention, the system 100 comprises a proportional dosing system that allows to proportionally dose a methane reducer, such as 3-nitrooxypropanol (3-NOP) or nitrate supplements, to the water. The dosing system comprises multiple dosing units 15 arranged at the pipes 13 to allow dosing individual amounts of methane reducers to individual watering points 14. Alternatively or additionally, there could also be one central dosing unit at the tank 12.

[0035] Further, according to the invention, the system 100 comprises sensing units 20 that can be arranged along the pipe 13 between the dosing units 15 and the watering points 14, or at the watering points 14, to monitor a concentration of the methane reducer at the watering points 14. The sensing units 20 electrochemical sensing units and can be designed as described further below in connection with Fig. 2.

[0036] Both the dosing units 15 and the sensing units 20 are connected to a central control unit 30 of the system, which is configured to adjust the amount of methane reducer that is added to the water based on the concentrations measured in dosing units 15. A target concentration of methane reducer can be adjusted based on factors like predicted animal water consumption rates, animal type, environmental conditions, etc.

[0037] As shown in Fig. 2, the pipes 13 comprise a bypass 13a and the sensing unit 20 is arranged at this bypass 13a configured to measure the concentration of methane reducer in the pipe 13 via measurement of the concentration in the bypass 13a.

[0038] The electrochemical sensing unit 20 comprises three electrodes, namely a working electrode 21 , a reference electrode 22 and a counter electrode 23.

[0039] The working electrode 21 is the primary sensing element where the redox reactions of the analyte, for example the nitrooxy group of 3-NOP occur. Carbon-based electrodes such as screen-printed carbon electrodes (SPCEs), glassy carbon electrodes (GCEs), or modified carbon nanotube (CNT)-based electrodes can be used in exemplary embodiments. The working electrode 21 may be modified with metal nanoparticles (e.g., gold or silver nanoparticles) or carbon nanomaterials like graphene or CNTs. These modifications may enhance the electrochemical activity by improving the surface area, electron transfer rate, and selectivity toward nitro compounds. In addition, functionalization of the working electrode 21 with specific chemical groups, such as amines or thiols, may further improve the sensitivity of the electrode by facilitating adsorption or redox reactions. Also, to improve the selectivity of the sensor in the presence of other electroactive substances, the surface of the working electrode 21 may be coated with molecularly imprinted polymers (MIPs) or specific recognition elements that selectively bind 3-NOP, bromoform or nitro compounds. For example, conducting polymers like polypyrrole (PPy) or polyaniline (PANI) can be electropolymerized onto the working electrode, providing a matrix that interacts preferentially with 3-NOP or nitro groups.

[0040] The reference electrode 22 can be a standard reference electrode, for example, an Ag / AgCI or saturated calomel electrode. The function of the reference electrode 22 is providing a stable potential against which the potential of the working electrode 21 is measured. The counter electrode 23 can be a platinum wire or carbon electrode. The counter electrode 23 completes the circuit and ensures the current flows during the redox reactions.

[0041] The electrodes 21-23 can be immersed in an electrolyte solution 24, which can include a buffer solution, for example a phosphate buffer solution for pH 6-8 or an acetate buffer for pH 4-6. An electrolyte can include, for example, chlorides or hydroxides of sodium or potassium. The working electrode 21 may be in direct contact with the water containing the analyte. Alternatively, as shown in Fig. 2, there may be a suitable membrane 25 in between.

[0042] Electrochemical sensors are sensible to components that may undergo characteristic electrochemical reduction or oxidation reactions at the working electrode 21 . For example, the nitrooxy group of 3-NOP can undergo a characteristic electrochemical reduction at the working electrode 21 , which can be measured by cyclic voltammetry (CV).

[0043] In CV, a potential is applied to the working electrode 21 , and it is swept linearly from a starting value to a maximum potential and then back to the starting point. During this process, the current is measured, and redox peaks corresponding to the reduction and oxidation of the relevant functional groups of the analyte are observed. The potential range for the CV scan is chosen based on the redox behavior of relevant groups of the analyte. For the nitrooxy groups of 3-NOP, the potential window can be from 0.4 V to -1.75 V versus Ag / AgCI, where the reduction of nitrooxy group occurs. The scan rate is selected based on the desired resolution and speed of the measurement. Exemplary values that may be appropriate for the application of the present invention may be 50 to 500 mV / s. Faster scan rates result in sharper peaks but may reduce sensitivity. Peaks in the CV correspond to the reduction (cathodic) and oxidation (anodic) of the relevant groups, for example nitrooxy groups. The peak current is proportional to the concentration of the group-carrying compound in the water sample, allowing for quantitative analysis.

[0044] A schematic flow-diagram of a method of the invention is shown in Fig. 3. At step 101 , the concentration of a methane reducer, such as 3-NOP, is measured using a sensing unit 20. The measured value is communicated to control unit 30. At step 102, in control unit 30, it is determined whether the measured concentration is within a certain range around a target concentration. If yes, in step 103a, the addition rate of the methane reducer at dosing unit 15 remains constant. If no, in step 103b, the addition rate is adjusted. The routine then ends and can be restarted after a certain waiting interval.

Claims

Claims1. A method for supplying drinking water with added methane reducer to animals, the method comprising the following steps: supplying drinking water to at least one watering point for animals, preferably a drinking trough; adding a methane reducer to the water using a dosing unit; measuring a concentration of the methane reducer at a position downstream the dosing unit using a sensing unit, wherein the sensing unit preferably comprises an electrochemical sensor and the measuring is preferably an electrochemical measuring; adjusting the amount of methane reducer that is added to the water based on the measured concentration.

2. The method of claim 1 , wherein the methane reducer is selected from 3- nitrooxypropanol, bromoform, and nitrate, and is preferably 3-nitrooxypropanol.

3. The method of any preceding claim, wherein the measuring is cyclic voltammetry, amperometry, potentiometry, or impedance spectroscopy, and is preferably cyclic voltammetry.

4. The method of any preceding claim, wherein a working electrode of the electrochemical sensor is selected from screen-printed carbon electrodes, glassy carbon electrodes and modified carbon nanotube based electrodes.

5. The method of any preceding claim, wherein a working electrode of the electrochemical sensor comprises a surface modification, preferably selected from metal nanoparticles, such as Au, Ag or Pt nanoparticles, metal oxide nanoparticles, such as TiC>2, ZnO or MnC>2 nanoparticles, carbon-based nanomaterials, such as graphene or carbon nanotubes, conducting polymers, such as polypyrrole, polyaniline or poly(3,4- ethylenedioxy thiophene), metal-polymer or metal-carbon nanocomposites, such as gold-graphene nanocomposites, ionic liquids, molecularly imprinted polymers, enzyme, antibody or other biological modifications, and combinations thereof.

6. The method of any one of the preceding claims, wherein the sensing unit undergoes a cleaning protocol, preferably after each use or measurement, after a certain time, after a certain number of measurements, or in response to a certain condition.

7. The method of any one of the preceding claims, wherein the measurement uses water that is diverted from the watering point in, for example, a drain or in a bypass.

8. A system for supplying drinking water with added methane reducer to animals, the system comprising: a drinking water system for animals including at least one watering point and configured for supplying water to the watering point, preferably a drinking trough; a dosing unit that is configured to add a controllable amount of a methane reducer to the water that is supplied to the watering point; a sensing unit configured to measure the concentration of methane reducer downstream the dosing unit, wherein the sensing unit preferably comprises an electrochemical sensor; a control unit connected to the sensing unit and the dosing unit and configured to adjust the amount of methane reducer that is added to the water based on the measured concentration.

9. The system of claim 8, wherein the methane reducer is selected from 3-nitrooxypropanol, bromoform, and nitrate, and is preferably 3-nitrooxypropanol.

10. The system of any one of claims 8 to 9, wherein the sensing unit is configured for cyclic voltammetry, amperometry, potentiometry, or impedance spectroscopy measurement, and is preferably configured for cyclic voltammetry measurement.

11. The system of any one of claims 8 to 10, wherein a working electrode of the electrochemical sensor is selected from screen-printed carbon electrodes, glassy carbon electrodes and modified carbon nanotube based electrodes.

12. The system of any one of claims 8 to 11 , wherein a working electrode of the electrochemical sensor comprises a surface modification, preferably selected from metal nanoparticles, such as Au, Ag or Pt nanoparticles, metal oxide nanoparticles, such as TiC>2, ZnO or MnC>2 nanoparticles, carbon-based nanomaterials, such as graphene or carbon nanotubes, conducting polymers, such as polypyrrole, polyaniline or poly(3,4- ethylenedioxy thiophene), metal-polymer or metal-carbon nanocomposites, such as gold-graphene nanocomposites, ionic liquids, molecularly imprinted polymers, enzyme, antibody or other biological modifications, and combinations thereof.

13. The system of any one of claims 8 to 12, wherein the sensing unit is configured to undergo a cleaning protocol, preferably after each use or measurement, after a certain time, after a certain number of measurements, or in response to a certain condition.

14. The system of any one of claims 8 to 9, wherein the system comprises a drain or bypass to divert water from the watering point and the sensing unit is configured to measure the concentration of methane reducer via measurement of the concentration in the drain or bypass.

15. A sensing unit for a system of any one of claims 8 to 14.

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