Patent Publication Number: US-8109233-B2

Title: Method for collecting milk in a milk tank, milking system and computer program products

Description:
FIELD OF THE INVENTION 
     The invention relates to the field of automatic milking of animals, and in particular to a method for collecting milk in a milk tank based on its quality. The invention also relates to a milking system and computer program products for implementing the method. 
     BACKGROUND OF THE INVENTION 
     The milk from a milking animal, such as a cow, is of a certain quality. The milk quality can be defined in different ways, such as for example in terms of its fat content or as having a certain cell count value. Further, the quality level may depend on various factors, for example the feed she is given, her health, her age, stage of lactation, or intervals between milking occasions, to mention a few factors. Besides such environmental factors, the milk quality also depends on genetic factors; the potential fat content of milk from an individual cow is to some extent determined genetically, as are protein and lactose levels. 
     Depending on its quality, the milk is suitable for different purposes, for example suitable for producing different types of milk-related products. The milk can e.g. be adequate either for direct consumption, for the processing into high-quality products such as cheese, butter or yogurt, for feeding calves or it may be totally unfit for any use. 
     There are a number of regulations to follow, in which the quality level required for a certain use is stated. For example, it may be regulated that the somatic cell count has to be below a value of 400,000 cells/ml in order for the milk to be consumed by people. 
     Today, when a farmer delivers an amount of milk to a dairy producer he can obtain an indication of the milk quality as measured by the dairy producer. Alternatively, he may manually measure the quality of the milk in the milk tank at any desired point of time. 
     SUMMARY OF THE INVENTION 
     However, it would be advantageous to be able to predict and even control the quality of the milk to be delivered so that the quality aimed at is achieved and so that the milk is thereby indeed suitable for a particular desired use. For example, for a farmer wishing to obtain milk suitable for producing a certain kind of cheese it would be desirable to be able to ensure that the milk to be delivered indeed has a quality level that fulfils the requirements for this intended purpose. 
     It is therefore a general object of the invention to provide means for enabling a user, such as a farmer, to control, or regulate the quality of milk to be delivered. 
     It is another object of the invention to provide means for enabling a user to optimize the use of milk produced in a dairy farm. 
     It is yet another object of the invention to provide means for enabling a prediction of the quality of the milk from a number of identified milking animals. In particular, it is an object of the invention to provide means for estimating/predicting in advance how the milk of a particular milking animal would affect the quality level of the total amount of milk from all milking animals. 
     It is yet another object of the invention to provide means for collecting the milk in a milk tank in dependence on the quality of the milk and in dependence on the prediction. 
     These objects, among others, are obtained by a method, by a milking system and by computer program products as claimed in the independent claims. 
     In accordance with the invention, a method is provided for collecting milk in a milk tank. The method comprises the steps of: milking a milking animal of a herd of milking animals by means of a milking station; establishing a quality parameter for the milk obtained from the milking animal during the milking; estimating a quality level of the total amount of milk, from a plurality of animals, in a milk tank connected to the milking station, wherein the estimation is based at least on the quality parameter; and collecting, in the milk tank, the milk obtained from the step of milking if the result from the estimation indicates that the quality of the total amount of milk, from a plurality of animals, in the milk tank would then result in a desired quality level. By means of the invention, a farmer may estimate in advance how the milk from a particular milking animal would affect the quality level of the milk that have already been milked and collected in a milk tank. He may thereby decide whether or not to discard the milk from this particular animal. Further, a farmer wishing to deliver milk of a certain quality, for example suitable for human consumption, can thereby make sure that the milk has indeed the quality required for the intended purpose. 
     In accordance with an embodiment of the invention, the method comprises the further step of predicting the milk quality of the milk in the milk tank when the milk tank is full. This prediction can be based on individual data for all milking animals of a herd. The step of collecting may then be based also on the prediction. A tool for affecting and controlling the milk quality is thereby provided, and a farmer wishing to deliver milk suitable for a certain type of cheese can be sure to be able to deliver milk of a quality fulfilling requirements for such use. In particular, a farmer may predict in advance how the milk from the particular milking animal would affect the quality level of the milk that have already been milked and collected in a milk tank and also how the milk quality from the remaining milking animals to be milked will affect the quality. He may thereby, for example, decide to collect the milk from this particular animal in the milk tank, even though the milk is of lower quality. An optimized usage of milk is thereby provided. 
     In accordance with another embodiment, the milk quality parameter is a cell-count value and the step of establishing a milk quality parameter comprises performing a cell count measurement. The cell count measurement can be automatically or manually performed. This is a convenient means for establishing a milk quality parameter. The cell count value also provides an excellent reliability of the estimation result of the milk quality of milk tank when full. 
     In accordance with yet, another embodiment, the method comprises the step of identifying the milking animal and the step of establishing a milk quality parameter comprises estimating a cell-count value based on historical data for the identified milking animal. This provides a non-expensive and simple means for establishing the milk quality parameter, yet having a satisfactory reliability. 
     In accordance with still another embodiment, the step of estimating comprises utilizing a mathematical function having as input one or more of following parameters: the number of times each milking animal is milked each day, an estimated cell count value for one or more milking animals, a measured cell count value for one or more milking animals, the volume of milk obtained at each milking occasion, the volume of the milk tank. Easily obtainable parameters can thus be used for estimating the milk quality of the milk in the milk tank. 
     In accordance with yet another embodiment, the method comprises the further step of collecting the milk from the milking animal in another milk tank if the result from the estimation indicates that the quality of the milk in the milk tank would fall below the desired quality level. The milk from this other milk tank may then be suitable for a different use. Further, if the milk is totally unsuitable for any use, the milk can be led to a drain. Further yet, the desired quality level is preferably chosen so as to obtain milk of a quality suitable for an intended use. An optimization of the milk usage can thereby be provided. 
     In accordance with a further aspect of the invention computer program products are provided, whereby advantages similar to the above are achieved. In particular, the invention may thereby easily be implemented in already existing milking systems. 
     Further characteristics of the invention and advantages thereof will be evident from the detailed description of embodiments of the present invention given hereinafter and the accompanying figures, which are only given by way of illustration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a milking system in which the present invention may be implemented. 
         FIG. 2  illustrates a flow chart of steps included in a method in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates schematically a milking system in which the present invention may be implemented. Only parts relevant for understanding the present invention are mentioned in the following. It is realized that the milking system comprises other parts as well. 
     The milking system comprises one or more milking station(s)  1  suitable for voluntary milking of cows. In such voluntary milking system the freely walking cow enters the milking station  1  in order to be milked on a voluntary basis. The milking system  1  comprises an automatic milking machine (not explicitly illustrated) including teat cups  2  connected to an end unit  11  (not shown to scale) by means of milk lines, part of which are shown at  8 . From the end unit  11 , the milk is directed via milk lines (schematically indicated by dashed lines) to a milk tank  10 . The milk tank  10  is not shown to scale, and may in a typical case be dimensioned to hold milk from all the milking animals of a herd obtained during one or two days. All milking stations  1  of the milking system are typically connected to the milk tank  10 . 
     The milking station  1  further comprises a milking robot or automatic handling device  3  including a processing and control device  4  and a robot arm  5 . The milking robot  3  is arranged to automatically apply the teat cups  2  of the milking machine to the teats of a cow  6 . 
     The processing and control device  4  is responsible for processing and controlling various actions in the milking station  1 , such as activities in connection with the milking e.g. opening and closing of gates, controlling the milking machine and its handling device  3 . The processing and control device  4 , in the following denoted computer  4 , typically comprises a microcomputer and suitable software. The computer  4  further preferably comprises a database  7  including information about each of the cows milked by the milking machine, for example information about when the respective cow was last milked, when the cow was last fed, the milk production of the cow etc. The database  7  is continuously updated and contains data relating to the individual cows in the milking herd. In the figure the database  7  is shown as a separate entity, it may however be integrated with the computer  4 . 
     The milking station  1  further comprises means for establishing a quality parameter for the milk obtained from the first milking animal. An example of such means comprises an on-line somatic cell counter or other somatic cell counter. In the following such somatic cell counters are denoted simply cell counter. 
     The method in accordance with the invention is next described with reference to  FIG. 2 . In the method  100  a milking animal that has entered the milking station  1  is milked (step  110 ) by means of the automatic handling device  3  of the milking station  1 . 
     A quality parameter is then established, in step  120 , for the milk obtained from the milking animal. For example, a quality parameter in the form of a cell count value (number of cells/mL) may be established by means of the cell counter. 
     Thereafter, in step  130 , the quality level of the total amount of milk in the milk tank  10  is estimated. This step is described more in detail later. 
     In step  140 , the milk is collected in the milk tank  10  in dependence on the result of the estimation. In particular, if the estimation reveals that the quality of the milk in the milk tank would decrease dramatically and result in that the milk would not be suitable for the intended use, then the milk may be directed to a drain or to another milk tank (not shown). If, however, the result from the estimation indicates that the milk in the milk tank  10  would obtain a desired quality level, then the milk is collected in the milk tank  10 . 
     Reverting to step  130 , the estimation may be performed in any suitable manner. In the following, the cell count value is taken as an example of the quality parameter. It is however noted that other quality parameters could be used. 
     In an embodiment of the invention, the cell count measurement, i.e. the establishment of the quality parameter, is performed at each milking occasion. The cell count value for the total amount of milk in the milk tank is then given by 
     
       
         
           
             
               
                 
                   
                     C 
                     tot 
                   
                   = 
                   
                     
                       
                         ∑ 
                         i 
                       
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         
                           V 
                           i 
                         
                         · 
                         
                           C 
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                         ∑ 
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                       ⁢ 
                       
                           
                       
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                         V 
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     where C tot  is the total cell count of the milk tank  10 , V i  is the amount of milk from milking occasion i and C i  is the cell count of the milk from milking occasion i. In this example, the cell-count value is established for each milking, which may be both time-consuming and expensive. However, the accuracy of the result, i.e. the estimated quality level of the milk in the milk tank  10 , is very high. 
     In another embodiment, a cell count measurement is not performed at each milking occasion, but only at selected occasions. Instead, an estimated cell count value for the particular, identified cow is provided. Such estimated cell-count value can be based on historical data, for example historical cell count results. All previously performed cell count results for the individual cow are preferably stored in the database  7  or the like. The data is accessible by means of the computer  4  connected to the automatic milking station  1 . When the cow enters the automatic milking station  1  she is identified and the relevant data for this particular cow is retrieved and the quality parameter is calculated based on the previous cell count values. As an example, if the cow is milked three times a day, the quality parameter for the milk from two of the milking occasions may be estimated based on historical data and an actual cell count measurement may be made for the milk from the third milking occasion. It is realized that the result in this case is not as accurate as in the previous embodiment, but highly satisfactory results is nevertheless obtained. 
     In yet another embodiment of the invention, the amount of milk in the milk tank for which a cell count measurement has been made can be kept track of. This can be used as an indication of the accuracy of the quality level of the milk in the milk tank  10 . If all milk in the milk tank  10  has undergone a cell count measurement, then the accuracy may be rated close to 100%. 
     In another embodiment of the invention, the quality of the milk in the milk tank  10 , when the milk tank  10  is full, is estimated in advance. Such estimation, or prediction really, may be based on individual data for all the cows in a herd. This is illustrated in  FIG. 2  as step  150 , which is an optional step. 
     In the following a simple example is used for illustrating the prediction and optimizing part of the invention (step  150 ). In this example, assume that a farmer has five cows. The amount of milk from the cows does not differ that much from milking occasion to milking occasion, so the amount of milk V 1 , V 2 , V 3 , V 4 , V 5  from each cow can be estimated with a relatively high accuracy. It is also to be noted that the amount is easily measured and that the calculations may be corrected when the milking is actually performed if there is a difference between the estimated value and the measured value. 
     The milk quality C 1 , C 2 , C 3 , C 4 , C 5  for milk from each respective cow may be estimated by means of historical cell count values. C i  may for example be an average of the latest x cell count results, e.g. based on the latest 3 cell count results: 
     
       
         
           
             
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               i 
             
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                   morning 
                 
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                   midday 
                 
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                   evening 
                 
               
               3 
             
           
         
       
     
     The predicted milk quality for the total amount of milk obtained during a single day, when the cows are milked 3 times during that day, may then be calculated as: 
     
       
         
           
             
               
                 C 
                 tot 
               
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     The milk tank may for example have a volume suitable for the milk from all milking occasions during two days. 
     Thus, 
     
       
         
           
             
               
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                   milk 
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     Now assume that the desired quality of the milk for the full tank is set to a certain value, C target . C tot  should not be allowed to exceed C target . One simple way to ensure this is to perform a cell count measurement for each cow and if the measured value exceeds the predicted value for a certain cow, then the milk is not used, i.e. is not collected in the milk tank. 
     However, it may happen that the milk actually obtained from one cow is of much better quality than what the expected milk quality value, C i , indicates. Then the milk from another cow, having a lower than expected milk quality may be, used anyway, without the total amount of milk in the milk tank  10  when full exceeding the target value C target . 
     The farmer may thus use a suitable algorithm for optimizing the amount of milk without exceeding the target value C target . That is, he may minimize the amount of milk that has to be discarded. 
     It is not necessary to perform cell count values for each and every milking occasion, but the fewer cell counts the lower accuracy. 
     The estimated cell count values may be weighted in dependence on how accurate the value is believed to be. For example, the accuracy of an estimated cell count value for a cow for which no cell count measurements have been made for some time may be set somewhat lower than cell count values from other cows, which have more recent measurement values. 
     The above calculations and idea may of course easily be extended to any number of cows owned by the farmer. The dilution effect may be used to a larger extent the higher the number of cows is. Further, it is noted that other algorithms than the one used to illustrate the invention may be utilized. For example, an algorithm based on one or more of: the number of times each milking animal is milked each day, an estimated cell count value for one or more milking animals, a measured cell count value for one or more milking animals, the volume of milk obtained at each milking occasion, the volume of the milk tank. 
     The decision whether or not to collect the milk from a certain, identified cow in the milk tank  10  may then be based on the prediction. The prediction may, in an embodiment of the invention, be continuously updated after each milking occasion. For example, if the amount of milk actually obtained from a cow is measured and found to differ substantially from the predicted amount, then the prediction may be updated accordingly. 
     An example of an algorithm that could be used for optimizing the milk quality and milk usage is given in the following: 
               C   ^     =           ∑   done     ⁢           ⁢       C   i     ⁢     V   i     ⁢     α   i         +       ∑     to_be   ⁢   _done       ⁢           ⁢         C   ~     i     ⁢       V   ~     i     ⁢     β   i                 ∑   done     ⁢           ⁢     V   i       +       ∑     to_be   ⁢   _done       ⁢           ⁢       V   ~     i                 
where:
 
     Ĉ=is the estimated quality 
     C i =is the measured/estimated cell counts of milkings already performed 
     V i =is the yield of milkings already performed 
     α i =is an uncertainty factor related to e.g. milking intervals 
     {tilde over (C)} i =estimated cell counts of milkings to be done before the next emptying of the milk tank 
     {tilde over (V)} i =estimated yield of these milkings to be performed 
     β i =uncertainty factor, could depend on the same factors as α i , or e.g. on variations in historical values (for example variations of cell counts or amount of milk) 
     If there is no uncertainty, then α i =β i =1. However, if there is some uncertainty, then β i ≦1 and α i &gt;1. This is only an exemplary algorithm. Other algorithms or modifications of the above exemplary algorithm may alternatively be used. 
     The present invention is suitable for implementation in an automated milking stall, but it can be implemented in any type of milking plant, i.e. a more or less manually performed milking or a semi-automated or fully automated milking environment. For example, a cell count measurement can be performed fully automatically or manually. If the cell count measurement is performed manually, the result is then inputted to the computer  4  or in another way made available for use in the method. 
     In another embodiment, the farmer wishes to obtain as high quality of the milk as possible and removes the milk from all cows having a cell count value (measured or estimated) above a certain level. 
     The invention is also related to a computer program product  20  that is loadable into an internal memory of a computer that is used for controlling the milking station. The computer program product  20  comprises software code portions for carrying out the method described above, when the computer program product is run on the computer. The invention is thus easily implemented in already existing milking systems. 
     The computer program product may alternatively be stored on a computer readable storage medium  21 , for example a compact disc. The computer readable storage medium  21  comprises computer readable program code means for causing the computer of the milking station to carry out the method described above. 
     Further, the invention also relates to a milking system. The milking system described in connection with  FIG. 1  comprises, besides the parts already described, a second milk tank, to which milk of different quality may be directed. The milking system also comprises means for establishing a quality parameter for the milk obtained from the milking animal, for example a cell counter. Further yet, the milking system comprises means for estimating a quality level of the total amount of milk in the milk tank  10 . Such means may be implemented by means of the above-mentioned computer program products. Lastly, the milking system comprises means for directing the milk obtained from the milking occasion to the milk tank  10  or to the second milk tank in dependence on a result from the estimation. Such means could for example comprise a simple three-way valve, the function of which is controlled, for example, by means of the computer  4 . 
     Throughout the description the cell count value has been used as an example of how to measure or define the quality of the milk. It is to be noted that other parameters could be used for defining a desired and actual quality level or quality value. For example, the quality level could be based on the fat content, the melatonine content, the lactose level or the protein content of the milk. 
     Further, throughout the description cows have been used as an example of milking animals. It is to be noted that the invention may be implemented for any kind of lactating animals. 
     In summary, the present invention provides a method for predicting the quality of milk in a milk tank. The milk in the milk tank may for example be delivered to a dairy producer intending to produce a certain type of cheese. The method provides a way for the farmer to ensure that the milk to be delivered to the dairy producer indeed fulfils quality requirements for this intended use.