Abstract:
An on-line somatic cell analyser and a method for evaluating the quantity of somatic cells present in a sample of milk are provided. A flow cell is connected to a milking hose and admits a constant volume of sampled milk into a flow chamber. A probe with two electrodes is positioned in a zone of optimal sensing inside the flow chamber and provides a modulated signal with an intensity value corresponding to the number of sodium ions present in the sample. A detection unit receives the modulated signal and generates a ion count signal whenever the number of sodium ions is above a reference value. A control unit converts the ion count signal into a somatic cell count (SCC) score. A step graph comprising a plurality of SCC thresholds defining a plurality of milk categories is stored in a memory and used by the control unit to classify the sample in a quality category according to the SCC score of the sample. A set of parameters characterizing the respective milk quality category, including presence of either infectious or environmental mastitis, are finally displayed.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/024,569, filed Feb. 17, 1998, now U.S. Pat. No. 6,031,367, issued Feb. 29, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention is generally concerned with milk quality analysis and in particular with an on-line, fully integrated somatic cell analyser. 
     2. Description of the Prior Art 
     The major cause of loss in dairy farming is an infection, known as mastitis, which occurs in an animal&#39;s udder. Mastitis is caused by contagious pathogens invading the udder and producing toxins that are harmful to the mammary glands. Generally, mastitis starts in one quarter. 
     Somatic cells, predominantly white cells and epithelial cells, enter the mammary gland as a result of damage to the alveolar lining by infection or chemical irritation. The counting of somatic cells excreted in the milk has become a widely used measure of mammary gland inflammation. The somatic cells can be counted by laborious direct microscopic method on stained milk smears, or the cell numbers can also be estimated by direct chemical tests. Other methods measure milk somatic cells indirectly or by determining the concentration of various by-products of the inflammatory response. 
     Somatic cell count (SCC), which is the number of white cells per millilitre of milk, increases in the bulk tank as mastitis spreads in the herd. SCC scores are used as an international standard in determining milk&#39;s quality and price. Most marketing organizations and regional authorities, regularly measure SCC on bulk tank milk and use these scores for penalty deductions and/or incentive payments. High SCC scores indicate the presence of mastitis in the herd and is reflected in the average score of the bulk tank. The bulk tank SCC is a good indicator of overall udder health and as good means for evaluating the mastitis control program. 
     It is also a high correlation between the bulk milk SCC and the average of individual animal counts. It is not uncommon for a few problem animals to be responsible for greater than 50% of the somatic cells in the bulk tank, particularly in small herds. It should be noted that animals with high milk production and intermediate SCC levels can have a significantly higher percentage of SCC contribution to the tank score than some high SCC cows with low production. 
     For high quality milk the SCC should be less than 200,000 cells/ml. Acceptable milk has SCC scores from 200,000 to 500,000 cells/ml. For infected animals, milk SCC scores are between 600,000 to 1.2M cells/ml. 
     When an animal in the herd becomes infected with infectious pathogens a rapid drop in milk production will be noted within 2 to 3 days. A high level of bacteria in an animal, causes an increased level of somatic cells in milk. An increased level of somatic cells in milk results in poorer quality milk products which are harder to process. About 80% of the losses attributed to a clinical episode involve the discarding of the nonsalable milk and decreased milk production. Additional losses are incurred by the farmer, such as premature culling and replacement heifer costs, or veterinary services and the cost for drugs. The loss is estimated to be US $184 per episode. In the USA alone, it is noted that over US$ 1 billion is lost in one year due to mastitis. The prevention procedures at milking are less efficient especially when the mastitis is in a subclinical phase and there are no visible signs of the disease. Special efforts have to be made at each milking to detect subclinical mastitis in individual animals before they become clinical episodes. 
     Milk production is also affected by the presence of environmental mastitis pathogens in animals. Generally, less than 10% of quarters in a herd are infected with environmental mastitis pathogens. Environmental mastitis causes a decrease in milk production but only to a mid level, where the SCC is between 350,000 to 500,000 cells/ml. Statistically, the risk factor for an animal with environmental mastitis pathogens to get infectious mastitis pathogens, is 60%. 
     Milk composition is influenced by many factors such as soil, feed, and water. It can also vary during milking, during the day, and with the season. The most frequent ions in milk are sodium and potassium ions which are transported passively from the secretory cells into the milk. Chloride ions are also found in milk but they have a higher concentration in the animal&#39;s blood and extracellular fluids than in milk. The concentration of potassium ions is relatively low in milk and the concentrations of sodium and chloride ions is relatively high. 
     Mastitis has a marked effect on milk composition. Generally, ion concentration in mastitic milk is higher than in normal milk. The electrical conductivity is higher in mastitic milk than in normal milk. In normal milk, electrical conductivity is about 3.1 miliSiemens/cm. A high electrical conductivity of milk of about 3.3 mS/cm indicates an infected quarter. The increase of electrical conductivity is due to an increase of sodium and chloride ion concentration. 
     Mastitis is currently detected by measuring changes in the electrical conductivity of milk. Electrical conductivity is generally measured with a DC or AC circuit having a probe positioned in the flow of milk. The most sensitive part of this on-line method is the probe. The probe generally includes two electrodes to which an AC or DC current is supplied to create an electrical circuit through the milk. The conductivity of the milk is evaluated by measuring the current variations in the circuitry that includes the probe. However, the readings are often inaccurate due to deposits of colloidal materials from the milk on the electrodes, and also due to polarization. Polarization occurs because some of the ions migrating towards the electrodes are not neutralized and consequently, an offset, or leakage current is generated between the electrodes. The presence of the leakage current results in inaccurate conductivity readings. 
     U.S. Pat. No. 3,762,371 issued to Joshua Creer Quayle et al. in 1973, describes an apparatus and a method for comparing the inductance of liquid streams for detecting mastitis. In this patent the suction teats engaging cup of a milking apparatus has a hemispherical chamber provided with four conductivity measuring cells. Each measuring cell includes a coil. The coils induce currents into the stream of milk from a quarter. The coils are placed in the arms of a four-arm electrical bridge which is balanced before testing. The induced currents change the impedance of the coil, depending on the electrical conductivity of the milk. An imbalance of the bridge during testing is due to variations in milk conductivity. 
     However, the system described in the above mentioned patent, is somehow complicated and not suitable for on-line measurements. Moreover, the system is based on the prediction that mastitis first occurs in one quarter, and can not detect mastitis occurring simultaneously in two or all quarters. 
     U.S. Pat. No. 5,416,417 issued to Eli Peles in 1995, discloses a method for determining the onset of mastitis by comparing the electrical conductivity of milk from an individual animal at milking with an average conductivity value previously recorded for the same animal. The average value corresponds to readings made during a predetermined period of time. A deviation between the measured electrical conductivity and the average value is determined at least once a day. Deviations of approximately 15% are considered an indication of the onset of mastitis. 
     This method does not provide an accurate indication about the type of mastitis or the degree of the infection. 
     U.S. Pat. No. 5,302,903 issued to Hendrik J. De Jong in 1994, describes a throughflow mastitis detector comprising two electrodes positioned at the bottom of a measuring chamber. The electrodes have a shank with a larger head projecting inside the measuring chamber, above and flush with the bottom surface, to avoid formation of areas where bacteria colonies may develop. This detector is not placed in an optimal sensing area. The milk flow is discontinued and obstructed by the measuring chamber. Moreover, milk fat/protein can build-up around electrodes causing current leakage. Also, cleaning the detector may be difficult. 
     Accordingly, there is a need for an improved on-line somatic cell analyser. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a milk analyser which alleviates totally or in part the drawbacks of the prior art. 
     It is another object of the present invention to provide an apparatus and a method for counting the somatic cells present in milk and to determine the quality of the milk in accordance with international standards. 
     It is a further object of the present invention to provide a device and a method for measuring a specific, reliable parameter in milk composition which gives an on-line, reliable SCC. 
     Still, another object of the present invention is to provide an accurate SCC indicator able to discriminate between a high SCC score recorded during the initial stage, for subclinical mastitis due to infectious pathogens, and same high SCC score recorded over a longer period of time, for clinical mastitis due to environmental pathogens. 
     According to one aspect of the invention, an on-line somatic cell analyser is provided. A flow cell having an inlet, an outlet, and a flow chamber is connected to the milking hose and admits a constant volume of liquid under test into the flow chamber. A probe with two electrodes is positioned within the flow chamber in a zone of optimal sensing and provides a modulated signal according to the number of sodium ions present in the sample. The analyser comprises detection means for providing an ion detection signal representing the number of sodium ions in the sample and for generating a ion count. Control means is also provided for receiving the ion count and for comparing same with a plurality of quality thresholds and for classifying the sample in a quality category. A set of parameters characterizing the respective quality category are finally displayed. 
     According to another aspect of the invention, a method for on-line measurement of the somatic cells present in milk is provided comprising the steps of inserting a flow cell in the flow of milk for providing a sample, measuring a ion detection signal representing the number of sodium ions in the sample, measuring a ion count based on the ion detection signal, converting the ion count into real time SCC, and comparing said real time SCC with a plurality of SCC thresholds for classifying the milk in a quality category. 
     The present invention provides for an on-line somatic cell analyser easy to use by a farmer, displaying SCC scores which are the international standards for evaluating the quality of the milk. The device of the present invention can be manufactured at a low cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood from the following description with reference to the drawings where: 
     FIG. 1A is a graph plotting SCC against sodium ion detections in the case of infectious mastitis; 
     FIG. 1B is a graph plotting SCC against sodium ion detections in the case of environmental mastitis; 
     FIG. 1C is a SCC—sodium ion detections calibration graph used by the somatic cell analyser of the present invention; 
     FIG. 2 is a block diagram of the somatic cell analyser of the present invention; 
     FIG. 3A is an exploded view of the flow cell of the present invention; 
     FIG. 3B is a schematic diagram of the analyser with the flow cell connected to a milking line; 
     FIG. 4 is a longitudinal sectional view of the flow cell of FIG. 3A along lines  4 - 4 ′ of FIG. 3A; 
     FIG. 5 is a transverse sectional view of the flow cell along lines  5 - 5 ′ of FIG. 3A; 
     FIG. 6 is a pictorial view of the sequences displayed by the analyser in the Milk Quality mode of operation; and 
     FIG. 7 is a pictorial view of a sequence displayed by the analyser when setup for both Milk Quality and Milk Yield modes of operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Milk has electrolytic properties. The number of sodium ions in milk chemistry appears to be the most reliable indicator of mastitis. Firstly, the number of sodium ions is higher compared to the number of any other ions present in milk and therefore, sodium ions can be counted with more accuracy. Secondly, the number of sodium ions is unaffected by other factors impacting on the conductivity of milk, but the somatic cells. Further on, the variations in the conductivity of milk can give, with proper calibration, the variations in the number of somatic cells present in milk. Based on this direct dependency, the present invention measures the conductivity of a constant volume of milk and displays a SCC score. 
     General and special tests were designed for testing selected samples of milk with and without sodium ions. The results of more than 2,000 milkings were used for calibrating the somatic cell analyser of the present invention, by transforming the milk conductivity variations into a number of sodium ion detections, and then correlating a somatic cell count to the number of sodium ion detections. 
     Based on experimental work and laboratory testing, a method and a somatic cell analyser have been developed for counting the sodium ions present in milk, the analyser being calibrated to display directly the number of somatic cells/ml of milk, according to the number of sodium ions detected. 
     Case 1: Infectious Mastitis 
     FIG. 1A is an experimental graph illustrating the relationship between the number of sodium ions detected in milk, shown on the abscissa, and the SCC scores, shown on the ordinate. The graph includes results from animals which developed infectious mastitis, and the data were sampled over a one week interval. The word “animal” designates here any milk producing animal. 
     The graph shows that an increase of sodium ions in milk is in direct relation to a rapid increase in the number of somatic cells, which is characteristic of infectious mastitis present in an animal. Line p 1 -p 6  interpolates the experimental results shown in discrete points p 1 -p 6.  This graph shows how the infectious mastitis develops, generally in less than 1 week. 
     Infectious mastitis causes an increase in the number of the sodium ions and a corresponding increase in the number of the somatic cells in milk. The increase in somatic cells is combined with a substantial decrease in milk production. As such, whenever the SCC reaches the level of +400,000 cells/ml in a short period of time, the animal must be isolated and treatment with antibiotics is required. 
     Case 2: Environmental Mastitis 
     Environmental mastitis develops in a period of time between 10 days to 4 months. The experiments show that in the case of environmental mastitis, the increase in density of sodium ions in milk is less dramatic compared to infectious cases. The SCC is practically constant at +300,000 cells/ml for a long period of time. This is partially due to the fact that the milk production does not decrease as much as in infectious cases. 
     As shown in FIG. 1B, sodium ion detections are in excess of 2,000 in section p 7 -p 8  of the graph, but the SCC is low, under the level of 400,000 cells/ml. Irrespective of the small SCC scores, when an animal presents over 2,000 sodium ion detections for a longer period of time, it requires special attention to determine the cause of the high sodium ion count. It can be caused by poor pond water, a foot infection, pneumonia, or E-coli bacteria which spread generally on hot summer days. In such a case, the sodium ion count will decrease by improving the sanitary conditions only, without using antibiotics. 
     Calibration Protocol 
     In practice, a precise measurement of the SCC scores is not critical. Therefore, the present invention proposes to use various levels of meaningful SCC scores, as shown in the step graph of FIG.  1 C. The two distinct sections p 1 -p 6  and p 7 -p 8  of the graph of FIG. 1C help identify when an animal is infected with mastitis, how severe the infection is, and what type of pathogens intruded into the udder. 
     The graph of FIG. 1C also illustrates how the somatic cell analyser is calibrated. Each SCC score is characteristic of a quality of milk. The seven SCC scores displayed by the analyser were selected for the reasons set out below: 
     “−200,000 cells/ml” denotes an uninfected animal with less than 200,000 cells/ml and corresponds to point p 1  shown on FIGS. 1A and 1C. A SCC score of −200,000 cells/ml displayed for point p, indicates the absence of sodium ions in milk and a very low number of somatic cells in milk. Such milk would qualify for a premium. 
     “+225,000 cells/ml” denotes an animal having over 200,000 cells/ml and corresponds to point P 2  shown on FIGS. 1A and 1C. This animal should be closely observed and supervised. 
     “+300,000 cells/ml” corresponds to points p 3,  shown on FIGS. 1A and 1C, and p 7 , shown on FIGS. 1B and 1C. Such a score can be associated with either infectious or environmental mastitis, depending on the number of sodium ion detected and taking also into account the length of time for the animal to reach and maintain this SCC. 
     “+500,000 cells/ml” is the Canadian somatic cell rejection level and corresponds to point p 4  shown on FIGS. 1A and 1C. This milk must be discarded. 
     “+750,000 cells/ml is the USA somatic cell rejection level and corresponds to point p 5  shown on FIGS. 1A and 1C. 
     “+1,000,000 cells/ml” is used more for laboratory testing and corresponds to point p 6  shown on FIGS. 1A and 1C. At this level of the infection the composition of the milk is visibly altered. 
     Six thresholds of sodium ion detections corresponding to the above identified SCC scores have been experimentally determined. The thresholds of sodium ion detections are: 0; 10; 40; 500; 1,100; and 2,000, respectively. 
     An additional SCC score “+300,000 cells/ml ENV MAS”, section p 7 -p 8  of FIGS. 1B and 1C, is identified with environmental mastitis. A SCC score of +300,000 cells/ml associated with a number of sodium ions detections in excess of 2,000, is relevant for animals with clinical environmental mastitis. 
     The seven SCC and the related thresholds are shown in Table 1 for easy reference. 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Graph 
                 Section 
                 p 1 -p 2   
                 p 2 -p 3   
                 p 3 -p 4   
                 p 4 -p 5   
                 p 5 -p 6   
                 p 7 -p 8   
               
               
                   
               
             
             
               
                 Detected 
                 0 
                 0 → 10 
                 11 → 40 
                 41 → 500 
                 501 → 1100 
                 1101 → 2000 
                 ≧2001 
               
               
                 SCC 
                 −200000 
                 +225000 
                 +300000 
                 +500000 
                 +750000 
                 +1M 
                 +300000 
               
               
                   
                   
                   
                   
                   
                   
                   
                 EnvMas 
               
               
                   
               
             
          
         
       
     
     The following is a description of the preferred embodiment of the invention. 
     FIG. 2 is a block diagram of an on-line, fully integrated somatic cell analyser  10  of the present invention. Device  10  comprises a power supply (not shown), a control unit  40 , a sodium ion detector  50 , and a display  60 . FIG. 2 also shows a flow cell  20  connected to the milk circuit for continuously sampling the milk, as it will be detailed in connection with FIGS. 3A,  3 B,  4 , and  5 . 
     The sodium ion detector  50  comprises a probe  30  which is embedded in a plastic support and placed inside flow cell  20 . Probe  30  has two electrodes  25  and  26 , in direct contact with the milk, and polarized with a signal provided by oscillator  51  on wire  16 . Oscillator  51  applies alternating current with a predetermined voltage and frequency to probe  30 . It has been determined through experiments that a 5V peak to peak signal at 4.92 kHz, is optimal for sensing variations of the impedance between electrodes  25  and  26 . In operation, the impedance between electrodes  25  and  26 , varies due to variations in conductivity of the liquid. Therefore, the signal received from oscillator  51  is modulated by probe  30  in accordance with the conductivity of the milk between electrodes  25  and  26 . 
     One input of a differential amplifier  56  is connected to probe  30  on line  18 , to receive the modulated signal, and the other input receives a fixed reference voltage (V ref ). Differential amplifier  56  compares the modulated signal with the reference voltage V ref  and outputs a ion detection signal each time the modulated signal is higher than V ref . A counter  58 , connected to the output of the differential amplifier  56 , counts during the period when the ion detection signal is present, and outputs a variable count (V count ) signal. Counter  58  measures the percentage “ON” time during which the modulated signal remains higher than V ref  and increments the V count  every 10 msec. V ref  is selected to give a V count =0 for milk with less than 200,000 cells/ml and it is assumed that in this case no sodium ions are detected by probe  30 . Counter  58  is set to zero before detector  50  starts sampling. 
     Control unit  40  receives the V count  signal and converts same to a SCC score to be displayed on display  60 . Control unit  40  controls the operation of detector  50 , compares the count from counter  58  with the sodium ion detection thresholds corresponding to each section p i −p i+1  of the graph of FIG. 1C, and provides a SCC score to display  60 . As it will be later described in connection with FIGS. 6 and 7, control unit  40  also receives information from a milk weight detector  45  providing data regarding the milk composition. Control unit  40  has two modes of operation namely Milk Quality Mode, wherein SCC scores are displayed, and Milk Yield Mode, wherein milk yield parameters are displayed. 
     The animal&#39;s body can act as a big capacitor causing a difference of voltage between the farm ground and the ground of device  10 . This difference may be between 1 to 3 volts, variable from farm to farm, and can cause electrode contamination. Optocouplers  53 - 55  are provided to isolate sensing circuit  50  from the power source. The galvanically isolation of the sodium ion detector  50  reduces the offset current and increases measurement accuracy. 
     A thermistor  42  is also embedded in a plastic support and located inside the flow cell  20 , close to probe  30 . Thermistor  42  is connected to control unit  40  through a wire  15 , for constantly providing unit  40  with on-line measurements of the milk temperature. The temperature is updated once every second and rounded up to the nearest 0.5° C. when displayed. Temperature monitoring at milking is an important parameter for decision making in herd management because it allows one to detect animals which are infected or under stress, and to take appropriate action. 
     FIG. 3A is an exploded view of the flow cell  20 , showing a left half  21  and a right half  22 . It is to be understood that left half  21  and right half  22  are defined relative to the view of FIG.  3 A. The position of the flow cell during sampling is irrelevant. When the left and the right halves are assembled, portion  27 ′ of the left half  21  and portion  27 ″ of the right half  22  form a frustroconical flow chamber  27  shown in FIG. 4 in further detail. Chamber  27  is defined by a large base wall  29 , a lateral wall  31 , and a small base forming an outlet  23 . An inlet  24  is provided in the right half  22  for receiving the milk along an axis X-X′, as indicated by arrow A. Probe  30  is placed inside chamber  27  on the opposite side of lateral wall  31  with respect to inlet  24 . Portion  23 ′ of the left half  21  and portion  23 ″ of the right half  22  form, when assembled, the cylindrical outlet  23  defining axis Y-Y′. Milk is discharged from flow cell  20  through outlet  23 , as indicated by arrow B. 
     FIG. 3B shows device  10  and flow cell  20  connected to the milk circuit. In general, the milk pipeline  70  travels along the milking stall in parallel to the vacuum line  72 . Modern stalls are also provided with a 24 volt AC (not shown) for supplying power to suction teats engaging cups  74 . Engaging cups  74  are attached to the pipeline  70  with a hook  76  or the like, provided with a handle  78  for moving cups  74  in and out of the milking position. Hook  76  also sup height for ease of reading. 
     When device  10  of the present invention is not used, engaging cups  74  are connected to pipeline  70  by a milking hose  11 . When analyser  10  is used, flow cell  20  is inserted between milking hose  11  and pipeline  70  by connecting milking hose  11  to inlet tube  24  and a pipeline insert hose  80  is provided between outlet  23  and pipeline  70 . Preferably, insert hose  80  is permanently attached to outlet  23 . The inner diameter of the tubes  24  and  23  is a standard ⅝ inch, while the outer diameter is ⅞ inch, to fit the standard milk hose diameter. The flow cell  20  is preferably made of plastic by injection moulding. Flow cell  20  samples all quarters through milking hose  11 . 
     Flow chamber  27  has an interior shape with improved flow dynamics, specially designed for accurate sampling. There are no milk flow obstructions which provides for a continuous flow inside flow cell  20 . The interior shape of flow chamber  27  also provides for a constant number of droplets per volume of milk, regardless of the rate of flow. This uniform distribution of the milk droplets inside flow chamber  27 , with no decrease in vacuum during milking, provides for accurate measurements and a one-time sampling of the milk, as it enters the flow cell  20 . The shape of chamber  27  is also selected to minimize impurities and milk fat build-up around electrodes  25  and  26 , by this minimizing the offset current. 
     FIG. 4 is a longitudinal sectional view along lines  4 - 4 ′ of FIG. 3A showing probe  30  inside flow chamber  27 . The axes of inlet  24  and outlet  23  are perpendicular on one another, defining an intersection point C in the centre of the flow chamber  27 . Probe  30  protrudes inside chamber  27  through the lateral wall  31  in an area diametrically opposed to inlet tube  24 . Probe  30  comprises a plastic support  32  unitary with wall  31  of flow cell  20 . It is important that electrodes  25  and  26 , have a definite surface exposed for contact with milk. Tips  35 ,  36  of electrodes  25  and  26 , are protruding through plastic bed  32  inside flow chamber  27  with a length “a” of approximately {fraction (1/20)} of an inch. Tips  35 ,  36 , better shown in FIG. 5, have flat, co-planar ends exposed to the flow of milk. Preferably, electrodes  25  and  26 , contact the milk in a zone adjacent to point C, which is considered the zone of optimal sensing, because in this area the swirl of the milk is designed to create a virtually foam-free zone around electrodes  25  and  26 , and the accuracy of the measurements is improved. 
     The other ends of electrodes  25  and  26  extend through plastic support  32  outwardly from flow chamber  27  and are provided with clamps  33 ,  34 , for connecting to wires  16  and  18 , respectively. 
     Thermistor  42  is located close to electrodes  25  and  26 , as shown in both FIGS. 4 and 5. A plastic cover  28  is provided at the exterior of flow chamber  27  for protecting the electrical connections. 
     FIG. 5 is a transverse sectional view along lines  5 - 5 ′ of FIG.  3 A. Electrodes  25  and  26  are symmetrically positioned with respect to axis X-X′ at a distance “d” from each other. A V-shaped portion  39  is formed between electrodes  25  and  26 . Distance “d” is chosen as small as permitted by moulding strengths and cleaning factors. A length of approximately {fraction (1/25)} of an inch is considered large enough to avoid the formation of deposits between electrodes and adequate for cleaning the flow cell after sampling. A suitable material for electrodes  25  and  26 , may be a {fraction (1/16)} of an inch, 304 stainless steel. 
     In operation, the analyser continuously displays data according to the SCC which is used as the international standard, as discussed before. The analyser of the present invention can also display the quantity of milk, butter fat percentage, protein percentage, milking time and the end-of-milking. 
     Milk Ouality Mode 
     Milk Quality mode displays the somatic cell count and milk temperature. After powering up, analyser  10  sequentially shows the information in displays  1 ,  2 , and  3 , as shown in FIG.  6 . After milk starts flowing, display  4  shows a rotating dial on the right upper comer of display  60  indicating that device  10  is operational, and milk temperature is displayed. 
     At the end of milking, the analyser indicates one of the displays  5  to  11 , corresponding to the seven SCC scores. If the reading is greater than 500,000 cells/ml, lamps  85  and  86  on the analyser  10  will flash indicating a high somatic cell count. 
     Milk Yield Mode and Milk Ouality Mode 
     In the Milk Yield mode the milk weight, the milking time, the protein and the fat content are displayed in addition to the SCC and the milk temperature. The constant volume of flow through cell  20  multiplied by the milking time provides the milk weight. Analyser  10  can be setup for Milk Quality mode only, for Milk Yield mode only, or for both modes, as shown in FIG.  7 . 
     Analyser  10  is shown at a much larger scale on FIG. 3B, to better illustrate the controls and the display. The somatic cell analyser  10  of the present invention is in fact a compact 145×105 cm box weighing half a kilogram. The LCD display  60  and red lamps  85 ,  86  are mounted inside the box under a transparent front face  90 . A jumper switch  88 , a reset button  84  and a reading button  82  are also disposed on the front face 90. The analyser  10  is fixed on hook  76  at a desired height. 
     Jumper switch  88  is used to switch modes by introducing new and modifying some existing operational amplifier parameters through software. This new circuitry is biased to the percentage of components in milk. This bias causes a maximum difference in count rate of 1.5%. The higher component level milk has a different viscosity causing a given amount of milk will act on probe  30  slightly longer. This causes a higher count per unit of milk. 
     Normal fat ranges are from about 3.6% to about 5.0%. Normal protein ranges are from about 2.9% to about 4.0%. Control unit  40  defaults the values to an average value 4.2% for fat, and 3.4% for protein. Given that fat and protein always move in proportion and that the outside values are close and that the circuitry is biased to milk components, device  45  can calculate a value in weight for fat and protein. This averaging technique provides an accuracy level of 0.05% in weight and consequently, makes device  10  also useful for feed management and nutrition requirement data collection. 
     In use, the farmer has to reset the analyser before each milking by pressing simultaneously the reading button  82  and the reset button  84 , and then starts milking. The analyser  10  will acknowledge the end-of-milking and the farmer has to press the reading button  82  for displaying the results. Jumper switch  88  can alternate the displayed results according to the Milk Quality mode or the Milk Yield mode. An alarm is set and lamps  85 ,  86 , flash if the SCC is over +500,000 cells/ml. The alarm can be set for any value of the SCC, according to the user&#39;s needs. 
     Numerous modifications, variations, and adaptations may be made to the particular embodiments of the invention described above, without departing from the scope of the invention as defined in the appended claims.