WO2010030184A1

WO2010030184A1 - Determination of infectious condition in a milk gland during milking

Info

Publication number: WO2010030184A1
Application number: PCT/NL2009/050550
Authority: WO
Inventors: Theodorus Johannes Maria Camu; Tjerk Martin Huitema
Original assignee: IDENTO OPERATIONS
Current assignee: IDENTO OPERATIONS
Priority date: 2008-09-12
Filing date: 2009-09-14
Publication date: 2010-03-18
Anticipated expiration: 2011-03-12
Also published as: NL1035925C; EP2334167A1

Abstract

Infection in a milk gland causes milk obtained to be discarded, and this disrupts a normal milking operation. The detection of an infection is efficiently made by observing the presence of clots in the milk. Frequently this is performed by observation of clots on a contrasting background. According to the invention the detection is performed by measuring and monitoring the resistance to flow through a substrate (8) on which the clots are deposited and partly block the passage. The results of the measurements are used to control CIP operations on the equipment that has been in touch with milk from an infected milk gland.

Description

Determination of infectious condition in a milk gland during milking .

The invention relates to a method and an apparatus for determining clinical or sub-clinical infection in a milk gland in the udders of milking animals. It furthermore relates to a use of an apparatus for controlling milking and excluding milk from infected milk glands.

Several principles for detecting such infections rely on the presence of smaller or larger clots in the milk.

Other principles rely on the conductivity or acidity of the liquid, or on the temporal distribution of the supply of milk from the gland.

Modern milking machinery has to perform according to established standards and practices which are based on an ability to detect infection in an animal in order that the milk delivered may be diverted from further use until the infection has subsided. For this reason it is not required that a detailed diagnosis or treatment plan is the result of determining the infection, only that it precisely informs about the condition during the regular milking operation. Furthermore, any part of milking machinery that has been in contact with infected milk must be cleaned, preferably by Cleaning In Place, CIP, force rinsing, washing or the similar.

To this purpose it has been determined that the collection of clots on a substrate that permits the passage of all other constituents of the raw milk is an efficient approach. The simplest method is visual inspection, such as it is described in US 4,385,590. The most used method of determining the presence of clots is optical, by measuring the reflection of the relatively bright clots against the background, which is made to appear darker by the control of materials and illumination. However, introducing a further complication in the form of photoelectrical components into an environment that is usually considered adverse to electronics entails the use of very expensive components and/or encapsulations, and the cleaning by rinsing or other CIP processes may be subjected to limitations, thereby increasing the cleaning time.

In US 3 485 086 a procedure is described for sampling the first milk prior to milking, using filter bottoms to individual chambers, into which milk from individual teats is directly squirted, and through which the milk is subsequently drawn by a transport vacuum. If one chamber empties slower than the others, this is taken as an indication that one supply teat has an infection, and this condition is monitored by taking e.g. daily samples. This is not a method that lends itself to in-line testing during the milking operation.

According to the invention a novel principle for detecting clots has been developed that eliminates the problems of the known solutions. The method is particular in that the pressure drop across the substrate is monitored to indicate that infection is present. The pressure drop is directly related to the amount of clots present on the substrate, because they occlude part of the surface and so increases the flow resistance through the substrate.

An infection in milk gland in the udders of a milking animal is determined by monitoring the hydrostatic pressure drop of the milk from the udders across the substrate. It has been found that such a rise in pressure acts as an indication for the pressure of clots resulting from an infection .

A further advantage of the method according to the invention is the applicability of the method in an online procedure. This improves the reliability of the measurements and/or the milk that is produced.

In an advantageous embodiment of the invention the pressure across the substrate is logged and that a pattern of generally increasing pressure is used as an indicator for the presence of clots. This has the particular advantage that a range of well-known pressure measuring sensors may be used.

In an advantageous embodiment of the invention the pressure is measured as the head of milk in the sensor chamber when the milk is streaming through the substrate. This has the particular advantage that the level is a particularly sensitive pressure indicator, in which a 10 mm change in level approximates a pressure change of 0.001 bar. In a further advantageous embodiment of the invention the head of milk is measured as the conductivity of the milk between electrodes that are covered by the milk as it rises in the sensor chamber due to a pressure increase. This has the particular advantage that a robust and reliable signal is obtained that can directly be converted to a tabular value .

In a still further advantageous embodiment of the invention further electrodes placed in the milk flow to the sensor chamber are used for measuring the specific conductivity of the milk, said specific conductivity being used to correct the conductivity measured between the first electrodes. The varying acidity of the milk, in particular if infection is present might shift the trigger point for the pressure that indicates clotting due to infection. By applying measurements of the specific conductivity it is possible to correct the pressure values measured. The term "specific conductivity" is common usage in electric measurements to mean a property of the liquid, rather than the conductivity measured between electrodes.

An apparatus for performing the method is particular in that it comprises a sensor chamber, an inlet for milk, a substrate, an outlet for milk and milk pressure sensing means for measuring the hydrostatic milk pressure at the substrate. This apparatus is able to be put into a milking line and perform the method irrespective of the means for measuring the milk pressure. Such apparatus provides the same effects and advantages as those related to the method.

An advantageous embodiment of the apparatus is particular in that the milk pressure sensor means comprise a flow resistance dependent column of milk in the sensor chamber and electrodes covered by milk to the height of the column and means for measuring the electrical conductivity between the electrodes. The column of milk that represents the pressure is measured directly by the increased conductivity as the milk level rises. A further advantageous embodiment is particular in that the milk pressure sensor means further comprise electrodes in the milk flow that enable the measurement of specific milk conductivity, said specific conductivity being used to correct the electrical conductivity measured between the electrodes.

A further advantageous embodiment is particular in that a blocking valve is placed in the outlet and that means for force rinsing are provided between the substrate and said blocking valve. This embodiment seals the downstream parts of the milking system from the liquid to be use when performing Cleaning In Place to remove the clots from the substrate . A further advantageous embodiment is particular in that a drain is provided on the same side of the substrate as the inlet. This drain permits the specific draining of the washing liquid, rather than letting it and the material removed by means of the CIP escape via an overflow that is otherwise dedicated to milk. This drain is closed by a valve during normal milking.

A further advantageous embodiment is particular in that control means enable a force rinsing operation to be initiated each time a pre-determined hydrostatic milk pressure development at the substrate has been determined by the pressure sensing means. By the control means the apparatus becomes self-sufficient and all milk that leaves the outlet will be useful and not contaminated by infection. A use of the apparatus for performing the method in a cow feeding, milking, and monitoring system is particular in that a message to said system accompanied by a cow reference number is sent simultaneously with the initiation of a force rinsing operation of the apparatus and the discharge of the milk from an infected gland to a container that is separate from containers for milk for consumption. This manner of using the apparatus ensures that the event of determining clots indicating infection and subsequent CIP does not go unnoticed, even though the apparatus may be self-sufficient in its functioning. Such use provides the same effects and advantages as those related to the method and/or apparatus.

The invention will be described in greater detail in the following with reference to the drawing, in which

- fig. 1 shows a side view of an embodiment of an apparatus for performing the invention;

- fig. 2 shows a section through the middle of the apparatus ; - fig. 3 shows a cross section of a different embodiment of an apparatus;

- fig. 4 is a vertical section in the direction A-A,

- fig. 5 is a vertical section in the direction B-B, and;

- fig. 6 is a basic schematic that shows the control system for measurement and self-cleaning and its connection to a milking cow administration system. In Fig. 1, milk from one or several teat cups enters the apparatus at a milk inlet 1, and gravity will permit it to exit from a milk outlet 2. The inlet 1 is close to the bottom of the apparatus, and preferably the milk enters tangentially into an essentially cylindrical chamber in order to permit any air admixed to the milk to be released and escape upwards. Furthermore, in this embodiment this keeps the flow away from the outlet 2 to avoid as much as possible any directed horizontal flow component. If this outlet is blocked, the chamber 3 is gradually filled with the milk, and if no change in the outlet conditions occur, or if the milking process is not halted, the milk will eventually pass through an overflow or bypass outlet 4 to be collected or otherwise disposed of.

The apparatus as shown consists of a top part 5 comprising the bypass outlet 4, a bottom part 6 comprising inlet 1 and outlet 2, and the chamber 3 placed in between, the whole being held together by long bolts 7. The chamber is made as a transparent cylinder, and gaskets ensure the tightness against leaks (from the inside to the outside) or contamination (from the outside to the inside) . The whole construction is designed for cleaning-in-place (CIP) . The construction shown is by no means limiting for possible other embodiments of the apparatus. In Fig. 2 the inside and operational parts of the apparatus are visible. Instead of passing directly from the inlet to the outlet 2 the milk passes through a substrate in the form of a mesh or filter structure 8 that is fitted tightly to the bottom part 6 at the outlet 2 by means of a ring 8a. This mesh or filter is dimensioned in such a way that normal milk containing water and fat globules passes through without creating more restriction in the flow that the milk rises up into the bottom part 6. If, however, clots are deposited on the filter 8 the restriction to the flow

(flow resistance) increases, because less free area is left for the flow, and the pressure to transport the milk through the filter increases. This pressure increase is directly noticeable by the rise of the milk level inside the apparatus; the pressure corresponds to the height of the column of milk.

The milk level may be detected by several means, including optical means or magnetic float means, but in the present embodiment it is detected by means of measurement of the conductivity between electrodes more or less covered by milk. These electrodes are thin and rod-shaped and shown at 9; they are vertically placed with connectors 10 at the top. The ends are supported by insulating means 11 to ensure that the distance between them is maintained. Suitable signal processing on the measurement values will indicate the average and peak levels of the milk as well as the development in level over time.

A fast clotting of the filter 8 will mean a steep development in the milk level, which is detected by the control system reacting on the measurement values. This means that the milk discharged via the bypass outlet 4 will be considered milk that is not useable in further dairy production and which is collected separately. To prepare for reuse after the milking machinery has been disconnected from the udder containing the diseased milk gland, the whole apparatus is flushed with warm water (CIP, cleaning-in-place) , in a direction preferably from the outlet 2, ensuring that all parts that have been in touch with the contaminated milk are cleaned. The substrate is completely regenerated thereby, and the apparatus is ready for the next milking operation. The identification code of the cow is logged and suitable treatment instituted. In a different embodiment shown in Fig. 3, the outlet 2 is on the side of the part 6, and a drain 12 has been placed in the bottom. This drain is closed during normal operation of the apparatus .

In Fig. 4 is seen a section through the apparatus in the direction A-A shown in Fig. 3. Some elements have been added for clarity. The substrate 8 in its holder 8a is mounted near the outlet 2. A valve to block flow through the outlet 2 of the apparatus is built-in, generally indicated at 13, and between this valve and the substrate a supply connection 14 for washing/rinsing liquid (hot water, admixed air under pressure, and possible chemical agents) is provided. The spent rinsing liquid may exit from the overflow outlet 4, but this would require disconnection from its normal connection. Instead the drain 12 is opened by means of a further valve, generally indicated at 15. Both the blocking valve and the drain valve may be spring loaded in order that the high pressure of the rinsing liquid closes the blocking valve 13 and opens the drain valve 15.

When the CIP operation is to begin, the valve 13 is closed, the valve 15 is opened, and the cleaning liquid is introduced by means of the supply connection 14. The substrate 8 is cleaned, and the removed aggregations (clots) are flushed through the drain 12. Rinsing is continued to remove any traces of milk from an infected teat. The valves 13 and 15 may be remotely controlled, and the whole CIP cycle may be automatic, triggered by the detection of clots on the substrate. As described, this is an indirect detection by means of the level of milk in the body 3 of the apparatus, but in principle any type of detection might be used as a trigger.

In Fig. 5 is seen a section through the apparatus in the direction B-B shown in Fig. 3. Some elements have been added for clarity. In particular, in this embodiment the number of electrodes has been increased to four, 9a-9b-9c- 9d, and two of the terminals 10c and 1Od are shown as well. The supplementary electrodes permit the continuous measurement of the specific conductivity of the milk, that is a measure that is independent of the level of milk, as well as measurement of the level dependent conductivity that is a measure of the pressure head of milk required to obtain a flow of milk through the apparatus. In practice it has been determined to be advantageous to multiplex the measurements between pairs of electrodes for these determinations, keeping track of the sets of measurements and performing calculations to derive the time-dependent level and its development that indicate clotting. By using the supplementary electrodes it is possible to obtain a higher precision that is compensated for variations in the specific conductivity of the milk. The greatest influence on specific conductivity of milk is an increase in acidity due to infection.

In Fig. 6 is shown a schematic diagram of the control system required to determine clotting and to initiate automatic CIP. Measuring leads are connected to the connectors 10a, 10b, 10c, 1Od of the measuring electrodes, and the resistance (or its reciprocal, the conductivity) between all combination of pairs of electrodes 9a, 9b, 9c, 9d (as described above) is measured by multiplexing (the data collector 16) between the pairs, and the results are stored for data analysis. At the time of collecting it, data relating to the specific conductivity of the milk will be intertwined with data relating to the level of milk, i.e. the pressure head of the milk. The data relating to specific conductivity is used to compensate the milk level data to provide a higher precision. The data is analysed (analyser 17) for the rapidity with which the level of milk rises, which is an indication of the severity of the gland infection. The data is registered in a milking management system 18 (which already receives many other inputs) relative to the cow in question, and an initiation signal is given to a valve controller 19 that stops the milking and activates valve 13 (stopping the flow of milk for consumption), valve 15 (opening the drain) and a supply valve to the supply line 14 of cleaning liquid, instituting a programme of cleaning in place (CIP) . When the last rinsing with hot water has been performed the valves are reset to normal milking operation, and milking resumes with another cow. All activities are logged in a further system 20 connected to the milking management system 18. It will be obvious to the skilled person how to integrate the above control arrangement into existing milking management systems .

In conclusion, the problem and its solution are essentially that infection in a milk gland causes milk obtained to be discarded, and this disrupts a normal milking operation. The detection of an infection is efficiently made by observing the presence of clots in the milk. Frequently this is performed by observation of clots on a contrasting background. According to the invention the detection is performed by measuring and monitoring the resistance to flow through a substrate on which the clots are deposited and partly block the passage. The results of the measurements are used to control CIP operations on the equipment that has been in touch with milk from an infected milk gland.

The foregoing description of the specific embodiments will so fully reveal the general nature of the present invention that others skilled in the art can, by applying current knowledge, readily modify or adapt for various applications such specific embodiments without undue experimentation and without departing from the generic concept, and therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The means, materials, and steps for carrying out various disclosed functions may take a variety of forms without departing from the invention. Thus, the expressions "means to ... " and "means for ...", or any method step language, as may be found in the specification above and/or in the claims below, followed by a functional statement, are intended to define and cover whatever structural, physical, chemical, or electrical element or structure, or whatever method step, which may now or in the future exist which carries out the recited functions, whether or not precisely equivalent to the embodiment or embodiments disclosed in the specification above, i.e., other means or steps for carrying out the same function can be used; and it is intended that such expressions be given their broadest interpretation.

Claims

C L A I M S

1. A method for determining infection in a milk gland in the udders of milking animals during the performance of a milking operation comprising collecting clots on a permeable substrate (8) placed in a sensor chamber (3, 5, 6) while milk is streaming through the substrate, characterised in that the hydrostatic pressure drop across the substrate (8) is monitored to determine a rise in pressure as an indicator for the presence of clots .

2. A method according to claim 1, characterised in that the pressure across the substrate (8) is logged and that a pattern of generally increasing pressure is used as an indicator for the presence of clots.

3. A method according to claim 1 or 2, characterised in that the pressure is measured as the head of milk in the sensor chamber when the milk is streaming through the substrate (8) .

4. A method according to claim 3, characterised in that the head of milk is measured as the conductivity of the milk between electrodes (9) that are covered by the milk as it rises in the sensor chamber (3) due to a pressure increase.

5. A method according to claim 4, characterised in that further electrodes (9a, 9b) placed in the milk flow to the sensor chamber are used for measuring the specific conductivity of the milk, said specific conductivity being used to correct the conductivity measured between electrodes (9c, 9d) .

6. A method according to any of claims 1-5, wherein a blocking valve blocks an outlet for milk, and activating means for forced rinsing, the means provided between the substrate and the blocking valve, for rinsing .

7. An apparatus for performing the method according to any of claims 1-6, characterised in that it comprises a sensor chamber (3, 5, 6), an inlet (1) for milk, a substrate, an outlet (2) for milk and milk pressure sensing means for measuring the hydrostatic milk pressure at the substrate (8) .

8. An apparatus according to claim 7, characterised in that the milk pressure sensor means comprise a flow resistance dependent column of milk in the sensor chamber (3) and electrodes (9,9c,9d) covered by milk to the height of the column and means for measuring the electrical conductivity between the electrodes (9, 9c, 9d) .

9. An apparatus according to claim 7 or 8, characterised in that the milk pressure sensor means further comprise electrodes (9a, 9b) in the milk flow that enable the measurement of specific milk conductivity, said specific conductivity being used to correct the electrical conductivity measured between the electrodes (9) .

10. An apparatus according to claim 7,8 or 9, characterised in that a blocking valve (13) is placed in the outlet and that means (14) for forced rinsing are provided between the substrate (8) and said blocking valve (13) .

11. An apparatus according to claim 10, characterised in that a drain (12) is provided on the same side of the substrate (8) as the inlet (1) .

12. An apparatus according to any of claims 7-11, characterised in that control means enable a force rinsing operation to be initiated each time a predetermined hydrostatic milk pressure development at the substrate (8) has been determined by the pressure sensing means.

13. Use of an apparatus according to any of claims 7-11 in a cow feeding, milking, and monitoring system (18), characterised in that a message to said system (18) accompanied by a cow reference number is sent simultaneously with the initiation of a force rinsing operation (19, 20) of the apparatus and the discharge of the milk from an infected gland to a container that is separate from containers for milk for consumption.