Introduction of Electronics Into Milking

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Computers and Electronics in Agriculture

30 (2001) 125149

Introduction of electronics into milkingtechnology

Dieter Ordolffa,b

a Institute for Process Engineering, Federal Dairy Research Centre, PO Box 6069,

24121 Kiel, Germanyb Institute for Production Engineering and Farm Building Research,

Federal Agricultural Research Centre, Bundesallee 50, 38116 Braunschweig, Germany

Abstract

In countries, like the former German Democratic Republic (GDR), where industrialized

milk production in large herds was the goal to be reached, research on automation of

machine milking was started more than 30 years ago. Initially, the main goal was to

mechanize operations at the end of the milking process. This work finally resulted in milking

devices that do not apply uniform parameters to all cows, but operate according to the milk

flow obtained from the cow actually to be milked. This evolution towards controlled

milking would not have been possible without application of electricity and electronic

components for sensors and control units. Also depending on the technical evolution of

electronic control systems are devices for recording milk yield and for taking samples for

milk analysis, which were available around the year 1980. At that time initial projects for

automatic milk recording were evaluated, which had an obvious influence on further

development of milk meters. The most demanding step of application of electronic control

systems up to now was the introduction of automatic milking systems. Here not only

application of teat cups has to be executed, it also is necessary to enable automatic checks

of udder condition, milk quality and other operations which may be challenging even for

trained human operators. Further evolution of electronic measurement procedures may be

important for the milk-producing farmer too, especially when on-line milk analysis is to be

introduced within the near future. 2001 Elsevier Science B.V. All rights reserved.

Keywords: Automation; Dairy production; Herd management; Milking; Sensors

www.elsevier.com/locate/compag

0168-1699/01/$ - see front matter 2001 Elsevier Science B.V. All rights reserved.

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D. Ordolff/Computers and Electronics in Agriculture 30 (2001) 125149126

1. Introduction

Milking cows (and other species) is known to be a very complex task, combining

physics (treatment of teats, control of the milking unit) and various biological

components (milk secretion, stimulation of the udder to obtain milk ejection),

including the risk of infecting the udder with pathogen microbes. Since hand

milking requires a considerable amount of physical force from the milking person,

it was obvious to look for a technical solution to take over the most demanding

part of this operation.First proposals for mechanical milking were presented more than 100 years ago,

but it took almost 50 years before the milking machine became a common

installation in milk producing farms at least in some parts of the world. Up to now

not all details of the interaction of this equipment with animals to be milked are yet

fully known.

Since the milking machine took over the most time consuming part of milking

routines, the milkers activities were restricted to foremilking, udder preparation,

attaching the milking cluster, stripping and taking off the milking cluster. While the

machine was milking one cow he was able to treat some additional cows. Depend-

ing on the design of the milking installation the milking person could handle from

two units of bucket milkers up to for or five units in milking parlours with pipelinemilking installation.

2. Controlled milking

Although labour requirement for milking was considerably reduced by machine

milking, it became quickly obvious that, due to irregular milking times of individual

cows, the operator was not always able to come back in time when a cow had

finished giving milk. This resulted in an increased amount of overmilking, com-

bined with a higher risk of damaged teats and of mastitis.

Especially in countries like the Soviet Union and the former German Democratic

Republic (GDR), where industrialized milk production in large herds was the goal

to be reached, research on automation of machine milking to reduce these risks was

started rather early. First results of initial investigations were available in 1955

(Bothur and Wehowsky, 1976).

Detection of the end of milking and automatic teat cup detaching were first steps

into automation of the milking process. Hoffmann and Wehowsky (1966) reported

about a new procedure to switch off the milking unit automatically at the end of

milking. For this purpose pulsation was stopped during the rest phase, and all four

teat cups remained at the udder without milking.

To detect the level of milk flow of 200 g/min, which was considered being the end

of a regular milking procedure, various sensors were developed (Bothur andWehowsky, 1976), based on optical, capacitive or inductive devices to detect low

milk flow or on a yield counting device using a tip tray (Fig. 1).


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D. Ordolff/Computers and Electronics in Agriculture 30 (2001) 125149 127

Initially, the flow sensor was directly connected to a relay to control a valve for

switching off pulsation or, in a further step, to activate a device for stripping and /or

taking off the teat cups (Fig. 2). The delay required between reaching the minimum

of milk flow and initializing the stop of milking mainly was taken care of by

appropriate design of the milk outlet in the flow measuring device.

This technology was first introduced in the GDR, where it had been developed

and where a very close cooperation existed between scientists at the Karl-Marx-

University at Leipzig and the only manufacturer of milking equipment. In the

FRG, at the Agricultural exhibition of the DLG (German Agricultural Society) inthe year 1972 several manufacturers (Miele, Alfa-Laval, Big Dutchman, Gascoigne)

for the first time presented this type of equipment (Ordolff, 1972). Technical

evolution not only improved reliability of components but in some cases resulted in

rather sophisticated products, up to milking units with teat cup removal by quarters

(Fig. 3).

Rather earlier, members of the working group at Leipzig also started research on

mechanized stimulation of the udder. It resulted in a patent by Troger (1965)

proposing the application of a positive pressure from 0.5 to 0.7 bar during the rest

phase of pulsation. Later on, higher pulse rates in combination with reduced

suction phase or a reduced level of milking vacuuum were also used for mechanical

stimulation. Initially, only pneumatic pulsators were available, later on electricallydriven devices became common which easily could be adapted in all parameters

according to the needs of stimulation.

While many scientists started discussing chances and risks of general application

of so-called semi-automatic milking units, evolution of automation of the milking

process continued. In a conference at the Technical University at Munchen-Wei-

henstephan (Germany) in the year 1977 a flow-controlled milking system was

presented by Stanzel (1977), with continuous variation of vacuum level, pulse rate

and pulse ratio, individually in each milking unit. Milk flow was measured by two

annular electrodes according to the liquid level in a pipe, placed in the long milk

tube. The resulting signals was compared with a reference, and when appropriate,

used for modification of the variable parameters mentioned before. At this time notall operations could be executed efficiently by electronic components, so electrome-

Fig. 1. Flow sensors to detect the end of milking (Bothur and Wehowsky, 1976) (I: light beam sensor;

II: tipping tray; III: level detector with bypass for high milkflow).


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Fig. 2. Partially automated milking unit with mechanical stripping (Klein et al., 1985) (I: pneumatic

connections; II: electric connections).

chanics were used to switch signals and to adjust voltage output of potentiometers.

More than 10 years were necessary before fully flow controlled milking was

introduced to the market, first by a manufacturer of electronic components in Israel

(S.C.R. Engineers Ltd., Netanya) (Fig. 4).

Here an inductive flow sensor gave the signals to control pulse rate and pulse

ratio according to milk flow (Fig. 5). Milking experiments with this device produced

higher milking speed and less stripping yield than conventional pulsation (Fig. 6).

These results may be explained by the fact that a shorter milking phase at low milk

flow at the beginning and at the end of the milking procedure allows teats to keep

their position in the liner, required for unrestricted milk flow, better than conven-

tional pulsation.Although the milking cluster itself is the most important part of a milking

installation, there are two more components, the milk pump in the terminal unit


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Fig. 3. Milking unit with teat cup removal by quarters.

and the vacuum pump, which more recently have been combined with electroniccontrols.

In standard installations both of them are dimensioned to handle the peak milk

flow and the maximum air flow respectively. The milk pump usually stops working

continuously below peak flow. Recently several manufacturers of milking equip-

ment presented milk pumps to be run at variable speed, controlled by the milk level

in the terminal unit, to adapt pump capacity to the amount of milk arriving in the

terminal unit. This solution has several advantages: the general flow speed of milk

is lower, so the mechanical load to the milk fat globules is reduced, resulting in less

mechanical damage and a lower level of lipolysis in the milk. Another advantage of

continuous milk flow with reduced speed is the improved efficiency of plate coolers

for instant refrigeration of milk before it enters the bulk tank.A conventional vacuum pump has to maintain a constant airflow, specific for the

vacuum level required for milking. Consequently the vacuum will drop, as soon as

Fig. 4. Inductive sensor for milk flow.


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Fig. 5. Example for flow controlled pulsation.

the air inlet into the milking installation exceeds this limit. This is an irregular

situation to be avoided by properly dimensioning the pump and by correctlyhandling the milking equipment. However, as soon as the actual airflow is below

peak flow, which should be the standard situation during milking, the vacuum level

will rise higher than necessary, even up to levels that may damage udder health.

Therefore a vacuum regulating device is required, adding the amount of air which

is not coming from the milking installation. So a constant vacuum level can be

maintained as long as airflow does not exceed the capacity of the vacuum pump.

Fig. 6. Performance of a standard and a flow-controlled milking unit.


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Especially in large milking installations this way of vacuum regulation requires big

pumps with a high energy consumption. Since maximum performance is only

necessary in some special situations, the effective capacity of a vacuum pump under

normal conditions may be reduced to the actual demand. This can be obtained by

varying the speed of the pump by an electronic control unit, linked to a sensor for

the actual milking vacuum. Ludington et al. (1990) observed an energy consump-

tion during milking which was reduced by at least 50%, providing better vacuum

stability than conventional systems. According to information obtained from

industry (e.g. Bou-Matic, Madison, WI, USA) power consumption for milking canbe reduced by up to 60%. Due to speed reduction, mechanical load of the pump will

also be lower. For safety reasons it may be wise, however, to install a conventional

vacuum regulator additionally to a pump with electronic speed control.

3. Milk yield recording

The general introduction of pipeline milking systems caused problems with

conventional procedures for milk recording, e.g. weighing the amount of milk

received in a bucket. To avoid the occasional use of milking buckets to check the

milk yield of individual cows recorder jars were installed in milking parlours, wherethe actual milk yield was to be read from a scale at each milking. This equipment,

however, was not suitable for stanchion barns. Mobile devices, so-called milkme-

ters, were used here to replace the bucket. They were equipped with a device to

have a proportional part of the total milk yield collected in a receiving jar with a

scale to read the amount of milk obtained. A major disadvantage of this kind of

metering devices was the need for manually taking samples for milk analysis, which

had to be done after thoroughly mixing the milk in the container. This was of

special importance when the total yield of a cow had been collected. Emptying the

containers also took a considerable amount of time, especially in milking parlours.

Nevertheless, a few electronic devices for reading out the amount of milk in the

recording jar are known. They were based on level detection by floats (still

available) or optical sensors (Cant, 1980), on weighing by load cells or on devices

volumetrically counting the amount of milk when the recording jar was emptied.

To overcome the inconvenience of recording jars, milkmeters based on continu-

ous measurement of milkflow were developed. Tipping trays were the first devices

in practical use for this purpose, similar to units for detecting the end of milk flow

described by Bothur and Wehowsky (1976). Initially, milk yield was indicated by a

pointer, mechanically driven by the tip tray (Fig. 7). Later on, the unit developed

in the GDR was equipped with an electronic display for milk yield. The most recent

version still is on the market and is approved by ICAR (International Committee

for Animal Recording).

Many manufacturers presented milkmeters with volumetric measuring systems.

First patent applications have been presented almost 40 years ago (Babson, 1963).For correct volumetric measurement care was to be taken to reduce or to compen-

sate the amount of air always included in milk coming from a milking unit (Fig. 8).


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Fig. 7. Milkmeter with tip tray and mechanic indication of milk yield.

Initially, volumetric milkmeters were designed for counting portions of milk with

constant volume. For this purpose measuring containers were to be filled with milk

up to a certain level. Suitable level detectors were floats and electrodes that made

flow low currents when they were immersed in milk.

As already mentioned, the variable mixture of air and milk complicated the

correct operation of volumetric measuring devices. Therefore various approaches

were were tried to eliminate this risk for accuracy. One of the early milkmeters, not

only approved by DHIA in USA but also on international level by ICAR and sold

in considerable quantities also in Europe, was developed in the late seventies in

Wisconsin, USA (Fig. 9). To separate milk from air, a tangential inlet made the

Fig. 8. Volumetric milkmeters are divided in sections to reduce the amount of air in the liquid entering

the measuring chamber.


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Fig. 9. Milkmeter measuring portions of constant volume.

milk flow in spirals down the wall of an almost cylindrical receiving vessel. At thebottom, there was a circular assembly of small containers with a relative wide

diameter in the lower part and a small diameter at the top. The bottom orifice of

these containers was covered by a peripheral seal in contact with the bottom of the

receiving vessel. These containers were rotated by an electric motor, controlled by

a float swimming in the milkair mixture in the receiving vessel. At a given point

of rotation, milk was flowing through a channel in the bottom of the receiving

vessel into the containers, filling them up to the outside milk level which corre-

sponded to their narrow bore part. Therefore variation of the milk level had only

a limited effect on the amount of milk collected. Just before the cycle was finished,

the containers passed an outlet to the milk tube. During each cycle the device took

away a defined quantity of milk. The total amount of milk passing the unit wascounted by magnetic sensors, corresponding to the positions of the milk containers,

and was indicated by an electronic display. A separate outlet for air, coming with

the milk from the milking unit, limited vacuum losses by the milkmeter to an

acceptable degree.

Another early volumetric milkmeter, which still is in use today, was designed at

a kibbutz in Israel. Milk here first enters a relatively large inlet chamber with an

outlet to the measuring chamber and a bypass for the air. The measuring chamber

beneath the inlet chamber is equipped with a magnet to control the passage of milk

by a double valve. When the magnet is not activated milk can flow into the

measuring chamber until the milk level for opening the outlet is reached. Then the

magnet lifts a pin, opening the outlet valve at the bottom and closing the inlet valveat the top at the same moment. Level detection is done by an array of three

electrodes. Two of them are installed at the bottom of the measuring chamber.


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Being covered by milk with a relatively low air content they give a reference signal

for the actual electrical conductivity. This is compared by the control unit with the

signal obtained by the third electrode, indicating the level corresponding to the

nominal volume of the measuring chamber (200 ml). That signal is not accepted

unless the levels of conductivity, indicated by the bottom electrode, and the

electrode at the top do roughly correspond. A lateral tube, connecting the measur-

ing chamber with the top area of the inlet chamber, gives room for foam covering

the relatively solid milk, which has to be present at the top electrode for proper

operation of the meter. This milkmeter needs more than a simple counting deviceto evaluate the signals from the level detecting electrodes. In fact the control unit

is also able to indicate electric conductivity of milk, to be used as an indicator for

udder health.

Even more complex are the control devices for another generation of milkmeters,

presented around 1983, and representing the state of the art up to now. The first

patent application, describing such a device, was published by Kiestra and Icking

(1981). Instead of measuring milk yield by counting constant portions, this milkme-

ter first calculates the actual flow rate, depending on the time to fill the measuring

chamber with the required amount of milk, and then it uses the time required for

emptying the measuring chamber to calculate the amount of milk leaving the

chamber (Fig. 10). From a mathematical point of view the meter calculates milkyield by integrating milk flow over time. This procedure allows to have the inlet

into the measuring chamber permanently open, resulting in less complex mechanics.

It took not much time to find more milkmeters of this kind on the market,

equipped either with volumetric or with weighing systems. The comparatively high

amount of calculations, required from the control unit, would not have been

possible without integrated circuits and microprocessors.

The accuracy of the first integrating meter, to be tested for approval for milk

recording, initially was not satisfiying. It took some time before it became clear that

flow patterns inside the meter were not linear. When the control unit was repro-

Fig. 10. Parameters for integration of milk flow over time (a) capacity of measuring chamber; (b) time

for one cycle; (c) time for charging the measuring chamber; (d) discharge time (Kiestra and Icking,

1981).


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Fig. 11. Milkmeter measuring continuous milkflow (Hoefelmayr and Maier, 1990).

grammed it worked correctly. Another problem with this device was that sudden

start or stop of milk flow on the test rig gave wrong readings. So not only the meter

had to be modified, the testing procedure too was to be adapted to the new

measuring principle.

Later on, as the number of meters, presented for ICAR approval, increased, it

was found that all measuring principles tended to behave in a nonlinear way,

especially at high milkflow. Increasing performance of control systems allowed to

linearize even devices with relatively instable physical behaviour. When farm

computers became more common, milkmeters were linked to them too. So it waspossible, beyond mere indication of milk yield and control of the milking unit, to

exchange data and to inform the milking personal in the parlour about details of

individual cows to be observed.

As mentioned earlier, Stanzel (1977) had presented a flow sensor with continuous

measurement of milk flow by annular electrodes. In its original version it was not

precise enough to be used as a milkmeter, but it was pointing towards another line

of milkmeters working with really continuous milkflow. One device of this kind

(Fig. 11), described by Hoefelmayr and Maier (1990), is equipped with an array of

about 60 vertically arranged electrodes for level detection, placed in a container

with restricted milk outlet. Milk flow is measured according to milk level. Here too

the milk yield is calculated by integration of flow over time. It also takes intoaccount the actual composition of the milkair mixture at each electrode, deter-

mined by electrical conductivity. To take samples for milk analysis, the expected


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milk yield of a cow to be milked, first has to be entered by the keyboard of the

milkmeter. The control unit then opens the inlet into the sample container at a

frequency proportional to milk flow. While other milkmeters require a two-step

sampling procedure, this meter directly fills an appropriate amount of milk into the

bottles, to be sent to the laboratory for analysis. The powerful software required for

the operation of this milkmeter offers some additional options for collecting data

related to individual cows. At the end of a milking session information is available

on patterns of milk flow and of electrical conductivity of milk from all cows which

were milked. The instrument is also equipped with a bar code reader to coordinatethe identity of sample bottles and cows.

To a certain extent this device is meeting demands for an automatic milk

recording system (AMR) which were first specified in 1955 in Denmark (Anon,

1982). In the Netherlands a list of specifications for an AMR system was defined in

1979. Among common demands to be fulfilled by milkmeters, there was asked for

possibilities of data storage and data transfer, identification of sample bottles and

simple and reliable identification of cows. Similar activities are known from other

countries, e.g. France and Germany. Consequently, industry and research organiza-

tions started developing devices to be used as AMR systems. One of them

originated in France, as a result of the cooperation of CEMAGREF (Centre

National du Machinisme Agricole, du Genie Rural, des Eaux et des Forets) atAnthony near Paris, and the company Lorraine-Cotibar, which then was manufac-

turing milking machines at Bar le Duc (France). It is described in a French patent

(Montalescot, 1981). Milk yield in this device was recorded volumetrically by

constant portions. Level detection in the measuring chamber was done by floats.

The signals were sent from the recording unit to the memory of a microprocessor

integrated into the device. Sampling was controlled by a valve that had a fixed

proportion of the total yield flowing into a primary container. When milking was

finished, the milk stocked here was mixed for uniform fat content and then a

constant quantity was filled into the final sample bottle. Fifteen sample bottles were

placed in a tray and were moved into sampling position by an electric motor. When

the milking session was over, data collected in the meter were copied onto a floppy

disc, to be sent to the laboratory together with the corresponding milk samples

(Fig. 12). In France some prototypes of this device have been used successfully

under farm conditions. Like another prototype of an AMR system, presented by

Foss Electric in Denmark at the same time (Fig. 13), it was never manufactured at

industrial level (Fig. 14). Finally, technical progress in milkmeters sold to farmers

today made the idea of an AMR system obsolete. But some special experience,

especially as far as preparation of milk samples is concerned, still is of interest in

relation with automatic milking systems.

4. Detection of mastitis

In all herds mastitis is one of the most common reasons for reduced milk yield

and for early losses of cows. The disease mainly is caused by biological activities of


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microbes which entered the udder, resulting in typical modifications of the mam-

mary gland and of milk. Resulting immunological reactions increase the secretion

of leucocytes in milk (Tolle et al., 1977; Guidry, 1985). Udder health therefore may

be evaluated by counting the number of somatic cells in milk. Infections of the

udder by pathogen microbes also increase the diffusion of Na+- and Cl-ions into

milk (Tolle et al., 1977; Guidry, 1985). The resulting higher level of electrical

conductivity of milk may also be used for mastitis detection.

Somatic cells actually only can be counted in laboratories. But there also are

indirect methods to detect infected quarters on the farm, like the california mastitistest (Schalm and Noorlander, 1957), based upon the reaction of special detergents

with DNA of somatic cells and changing viscosity of milk. This test was mecha-

nized by a ball viscosimeter (Tolle and Whittlestone, 1976).

However, electrical conductivity of milk seems to be the parameter best suited for

technical mastitis detection (Smith and Schultze, 1978). The most difficult problem

for routine application was to define a limit for detection of abnormal conditions.

Linzell and Peaker (1975) proposed to compare electrical conductivity of first

squirts of milk from each quarter. To detect infected quarters the conductivity

should exceed 16% of the lowest value observed.

In many projects it was tried to create devices for monitoring udder health, using

the interaction of mastitis and electrical conductivity of milk. Rossing and Maatje(1978), Maatje et al. (1983) described a milking claw which made milk from

individual quarters flow over sensor cells, equipped with electrodes made up of

polished stainless steel (Fig. 15). Electrical conductivity was continuously moni-

tored by measuring the loss of voltage every 8 s. Signal processing in a computer

provided a graphic presentation of results.

Reliability and repeatability of quarterwise measurement of conductivity was

found to depend on uniform sensor cells with clean electrodes. Coefficients of

correlation with results produced by laboratory equipment varied from 0.83 to 0.89.

Fig. 12. Unit for data collection linked to an AMR milkmeter.


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Fig. 13. Proposal for a device for automatic milk yield recording.

Results corresponded best when samples were taken during peak milk flow and

machine stripping. Highest conductivity was found at the start and at the end of

milking.

Rossing et al. (1987) presented results, obtained with this device in an experimen-

tal farm. Sensitivity of electrodes varied at about 4% of average conductivity.Number and status of lactation caused variation of comparable levels. Most

important, however, was the cow effect. Running averages turned out to be most

suitable for evaluation of results. About 75% of infected quarters were identified.

Puckett et al. (1983) also reported on experiments on monitoring electrical

conductivity in milking claws, equipped with sensor electrodes for quarterwise

cluster take off, when milkflow in the corresponding quarter had stopped. To

minimize influence of milk level in the sensor cell, which was proportional to milk

flow, various designs of electrodes were investigated. Best results were obtained

with a flat sensor surface at the end of the electrode.

Critical points for evaluation of signals were unsatisfactory differences of conduc-

tivity values from healthy and infected quarters and negative influence of onlypartially filled sensor cells. Best results were obtained by the average of five highest

values of each milking. Quarter specific values were compared with the total


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Fig. 14. Farm test of an AMR prototype.

average of all quarters. Integrating data from up to three milking procedures

avoided false positive or false negative results. As experiments continued, using the

quarter with the lowest conductivity was found to be the best reference.Lake (1987) designed a sensor without electrodes, measuring electrical conductiv-

ity by induction. Milk flow was split into two channels with annular configuration.

Two coils and the annular flow of milk formed an electrical transformer, transmit-

ting a signal with a frequency of approximately 50 kHz. The voltage in the

secondary circuit was proportional to the electrical conductivity of milk. By

Fig. 15. Claw equipped with electrodes for measuring electrical conductivity of milk (Rossing and

Maatje, 1978).


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avoiding phase shifts from primary to secondary circuit influence of temperature on

signals could be avoided. The device was only working correctly if solid milk was

flowing. It therefore required adapted milking units.

Schlunsen (1983) explained that also milk temperature could be used for mastitis

detection. In udders affected by mastitis, he observed a difference of 2 K above the

usual level of 38C, which was maintained for two or three milkings.

Smith and Schultze (1978) also pointed at body temperature of cows for mastitis

detection. Rossing et al. (1983a) found a difference of about 0.1 K between body

temperature and milk temperature, measured in the milking claw. Temperaturesmeasured in the long milk tube differed more from body temperature. Under

practical conditions most health problems could be detected.

Schlunsen (1985) placed the sensors for measuring electrical conductivity in front

of the inlets to the milking claw. At the same location temperature sensors had been

installed by Paul and Speckmann (1979). Data from sensors were continuously

recorded by computers. It was found, that temperature of all four quarters tended

to change in the same direction, and that the conductivity of milk only from an

infected quarter was modified. However, no indication for a critical level of

conductivity for the detection of mastitis was given.

5. Oestrus detection

Efficient oestrus detection is another important tool for herd management.

Primary parameters are concentrations in milk of hormones, e.g. progesterone

(Elsaesser, 1979), indicating fertility status of cows. However, they can only be

measured in laboratories.

Indirect parameters for oestrus detection are electrical conductivity of vaginal

secretion (Foote et al., 1978; Heckman et al., 1979; Marshal et al., 1979), milk

temperature (Ball et al., 1978; Rossing and Maatje, 1978; Persson et al., 1980;

Schlunsen et al., 1982) and behaviour of cows (Kiddy, 1977).

Observation of activity of cows by pedometers seemed to be the only parameter

really suited for automatic data collection. During oestrus Kiddy (1977) found an

activity level which was four times the normal value in loose housing systems and

almost three times the normal level in stanchion barns. When the limit was set to

an equivalent of 2 S.D. above average, 98% of oestrus events were to be detected

in loose housing systems and 93% in stanchion barns.

Similar results were obtained by Williams et al. (1981), Rossing et al. (1983b),

Maatje et al. (1987).

Technically, automatic oestrus detection meanwhile is mainly based on measur-

ing the activity of cows, as it was described by Kiddy (1977). Thompson and

Rodrian (1983) installed two different types of activity sensors at cows legs. One

device memorized the activity readings, which were transmitted by radio signals,

together with the cows identity, to a computer for further processing. The controlunit to start transmission and the receiver unit were proposed to be installed in the

milking parlour. For evaluation of the activity level readings, obtained during


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Fig. 16. Piezo-electric activity sensor (Gettens et al., 1986) (30,32: connections to signal processor; 34:

lead ball; 36: wires to keep lead ball in position; 40: piezo-electric element).

actual milking, were to be compared with previous data. The result of evaluation

was to be displayed by video screen, printer or, if activity was above a given level,

by optical signals. At normal conditions an activity level between 0.5 and 1.5 was

expected. During oestrus it should go up to 2.0 or higher.

A second device operated without data transmission. Cow activity was indicated

by a display with three light emitting diodes. Activity level was updated every hour

by a built in microprocessor. If activity level was below 2.0 no light signal was

emitted. For levels between 2.0 and 3.0 one light, between 3.0 and 4.0 two lights

and at higher levels all three-light started blinking. According to Machan (1980) up

to 80% of oestrus events were detected with this device, while it was run in a farm.

It was estimated that this technology could replace one person working in the barn.

According to experiences collected by Thompson and Rodrian (1983), inseminationshould be executed at the top level of activity.

Later on, several types of activity sensors were developed. The device designed by

Gettens et al. (1986) transformed movements of cows not only into signals to

indicate the level of activity, but also into electric power, required for data

transmission and potentially to be used for powering additional sensors (Fig. 16).

As research progressed, several approaches were investigated to improve the

reliablity of oestrus detection by using information from more than one parameter.

Thompson and Rodrian (1983) discussed monitoring activity, feed intake and milk

temperature. Combined use of maximum milk temperature and activity level was

proposed by Maatje et al. (1987). This allowed to reduce the proportion of

undiscovered oestrus events from 30 to 10%. A rather complex mix of parameterswas investigated by Schlunsen et al. (1987). They combined milk temperature,

electrical conductivity of milk, activity, feed intake, milk production and heart rate,

measured by an infrared sensor, fixed to the ear of the animal (Paul et al., 1984).

To improve the efficiency of oestrus detection and other complex management

tasks, Spahr et al. (1988) proposed to use expert systems to combine data from

different sensor systems.

6. Automatic milking systems (milking robots)

When engineers, scientists and farmers started thinking about automation ofmilking, some of them proceeded up to the most challenging operation in conven-

tional milking, the application of teat cups. Although initial proposals go back to


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the period of introduction of first components for controlled milking (Gabler, 1971;

Notsuki and Ueno, 1977), successful solutions were not to be expected before

powerful electronic sensing and controlling devices at moderate price were avail-

able. Fundamental work on automatic milking was done at IMAG-DLO in the

Netherlands, at CEMAGREF, France, at AFRC Institutes at Compton and Silsoe

in Great Britain, at the Federal Dairy Research Centre at Kiel (Germany) and at

the Agricultural Research Centre (FAL) at Braunschweig-Volkenrode (Germany).

Basic requirements for fully automatic milking are devices for teat localization

and for automatic handling of the milking unit. Although the temperature profile ofthe udder surface can provide reliable information of teat positions (Ordolff, 1984),

scanning by infrared thermometers has been found to be too slow for practical

application. Thermovision still is too expensive to be useful. Initially it also was

tried to determine the correct position for attaching the teat cup by mechanical

contact of the teat with a circular device, divided in sectors equipped with

conductivity sensors (Akermann, 1979, Fig. 17). Later on, various remote acting

sensors were commonly used to localize teats (Artmann and Schillingmann, 1990)

(Fig. 18). Digital image processing in combination with laser scanning procedures

(Montalescot, 1987) and ultrasonic range finding devices and/or optical sensors

(light beam matrix) have been successfully used for teat localization (Torsius, 1987;

Scheidemann, 1990). Storage of teat positions in a memory was used to simplify theoperation, especially by reducing the time required for long distance searching

procedures. For first approach of the handling device and for fine positioning a

double sensor system was often installed. To restrict the searching area or to

respond to changing positions of the cow, reference points at the cow were used by

the sensor system.

Teat cups may be attached simultaneously to all four teats or serially to single

teats. Initially, industrial robots have been used for handling the teat cups. Later

on, teat cups were handled by purpose designed equipment, either with one arm for

Fig. 17. Experimental device for teat localization by a galvanic sensor.


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Fig. 18. Sensors for teat detection in automatic milking systems (Artmann and Schillingmann, 1990).

each single teat cup, remaining attached permanently (Montalescot, 1987), or with

an unpowered support for the milking cluster, positioned by a powered arm which

is connected only temporarily (Verbrugge and Aurik, 1988), or using a single arm

to place teat cups, picked up from a magazine one by one (Scheidemann, 1990)

Fig. 19. Handling units for attachment of teat cups (Artmann and Schillingmann, 1990).


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Fig. 20. Prototype of a cartesian robot attaching teat cups.

(Figs. 19 and 20). Apart from electrical drive systems also pneumatically powered

devices have been proposed, demanding complex control units but providing a high

degree of elasticity when colliding with animals (Street and Frost, 1990).Software to control the attachment procedure is crucial for practical application

of handling units. Time required for attaching and success of the procedure largely

depends on routines for correcting errors during teat localization and attaching.

This was proved in an experiment, using relatively basic equipment for 1 year. Up

to 90% of attaching procedures were successful, if more than one trial was

permitted for each teat cup (Kremer and Ordolff, 1992).

It became very quickly clear that full automation of milking requires more than

just automatic attachment of teat cups and that components, already available in

conventional milking machines, as described earlier, were not always sufficient

either. A main problem was to replace human operators, doing the obligatory check

of the first squirts of milk for abnormality. A first approach, used up to now, wasto measure electrical conductivity of milk for this purpose.

Devices for separately collecting foremilk have been described by Dorofeev

(1987), Torsius (1987). Scheidemann (1990) reported about a device which, after

measurement of the electrical conductivity, had diverted by a second pipeline the

milk, obtained from single quarters, when pulsation was started. A bypass to a

second receiving container was installed for milk with a negative result for electrical

conductivity and for liquids, used for sanitizing and rinsing the milking unit after

each milking procedure.

Another potential problem was milk recording in connection with more frequent

milking at irregular intervals, which were to be expected from automatic milking

systems. Although recording milk yield was found not to be a major problem(Gottsch, 1990), taking samples automatically, as to be predicted according to

earlier experience with various AMR projects, included some risks as far as control


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of the sampling procedure and correct sample composition were concerned (Or-

dolff, 1997).

Today automatic milking systems are not stand-alone units, but are generally

linked to the central herd management computer for exchange of data of various

electronic components actually available, e.g. for recording cow activity and for

feeding concentrates.

7. Future prospects

Future applications of electronics in milk production probably will have less

impact on the milking procedure itself but will introduce sensors to take over tasks,

actually executed by man or by laboratories located some distance away from

farms.

Especially for operation of automatic milking systems in full accordance with

administrative regulations it will be necessary to develop sensors to evaluate

cleanliness and condition of udders and to check the status of foremilk. Publica-

tions are available indicating the direction of research and development to reach

this goal. Bull et al. (1995) investigated the feasibility of a sensor to detect dirt on

a teat by the optical reflectivity of the teat. They were able to identify spectralparameters corresponding to manure and blood on a clean teat. However, it was

not possible to discriminate reliably between black teats and those covered with soil

contaminants.

Fig. 21. Experimental milkmeter equipped to prepare samples for milk analysis on the farm.


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Tsenkova et al. (1992) proposed the use of Near Infrared Spectroscopy to

evaluate milk quality, including udder health. There are also indications that the

evaluation of visible colour may give information on the composition of milk

(Bergann and Schick, 1998).

To go this way farther, it can be expected that within reasonable time milk

analysis in place, e.g. during milking, will be reality. In France a project to reach

this goal has been run by the national milk recording association for many years

(Fig. 21). Actually, prototypes of such a system are said to be tried in several

departments. It can be expected that after successful introduction for officialpurposes similar equipment will also be available for general on-farm use.

References

Akermann, D.E., 1979. Verfahren und Vorrichtung zum Melken. (Procedure and device for Milking).

Deutsche Offenlegungsschrift 28 (49), 227.

Anon, 1982. Automatic Milk Production Recording, 2nd draft, CMD, Arnhem, Netherlands.

Artmann, R., Schillingmann, D., 1990. Entwicklungsstand von Melkrobotern. (State of the art of

milking robots). Landtechnik 45, 437440.

Babson, H.B., 1963. Milk Flow Measuring Apparatus, United States Patent 3 115 038.

Ball, P.J.H., Morant, S.V., Cant, E.J., 1978. Measurement of milk temperature as an aid to estrus

detection in cattle. J. Agric. Sci. Cambridge 91, 593597.

Bergann, T., Schick, M., 1998. Farbe von Konsummilch. (Colour of market milk). dmz 9, 464

468.

Bothur, D., Wehowsky, G., 1976. Beziehungen zwischen Milchstrom und Euterentleerung in der

Endphase des maschinellen Melkprozesses. (Correlation between milk flow and udder emptying in

terminal phase of mechanical milking). Monatshefte Veterinarmedizin 31 (19), 734 739.

Bull, C., Mottram, T., Wheeler, H., 1995. Optical teat inspection for automatic milking systems.

Comput. Electron. Agric. 12, 121130.

Cant, E.J., 1980. Milk yield recording. In: Proceedings of the Mechanization and Automation of Cattle

Production. British Society of Animal Production, pp. 4353 Occasional Publication No. 2.

Dorofeev, S.V., 1987. Arrangement for removing the first milk portions, USSR Patent

SU 1 281 217 A1.

Elsaesser, F., 1979. In welcher Weise kann die Milch-Progesteron-Bestimmung zur Verbesserung der

Fortpflanzungssteuerung beim Rind beitragen? (How can measurement of progesterone in milkcontribute to improvements of fertility control in cattle). Tierzuchter 31, 94 96.

Foote, R.H., Oltenacu, E.A.B., Mellinger, J., Scott, N.R., (1978). Pregnancy rate of Dairy Cows

inseminated on the basis of electronic probe measurements. J. Dairy Sci. 62, 6973.

Gabler, E., 1971. Melkeinrichtung, vorzugsweise fur groe Milchviehbestande, (Milking device, prefer-

ably for large herds) DDR patent 82 592.

Gettens, J.W., Sigrimis, N.A., Scott, N.R., 1986. Passive activity monitor for livestock, United States

patent 4 618 861.

Gottsch, H., 1990. Genauigkeit von Milchmengenmegeraten bei kleinen Gemelken. (Accuracy of milk

meters at low milk yields). Dipl. Arbeit, Inst. f. landw. Verfahrenstechnik, Uni. Kiel, cited in Ordolff,

D. (1992) Randprobleme des Robotermelkens (Peripheral problems of robotic milking). Landtechnik

47 (12), 631633.

Guidry, A.J., 1985. Mastitis and the immune system of the mammary gland. In: Larson, B.L. (Ed.),

Lactation. The Iowa State University Press, Ames, IA, pp. 229262.

Heckman, G.S., Katz, L.S., Foote, R.H., Oltenacu, E.A.B., Scott, N.R., Marshall, R.A., 1979. Estrus

cycle patterns in cattle monitored by electrical resistance and milk progesterone. J. Dairy Sci. 62,

6468.


23/25


Hoefelmayr, T., Maier, J., 1990. Milchflumesser. (Milk Flow Meter) German patent DE 3101302 C2.

Hoffmann, H.-W., Wehowsky, G., 1966. Ein neues Verfahren zum Abschalten der Melkzeuge gegen

Ende des Melkaktes. (A new procedure for switching off the milking units at the end of milking).

Agrartechnik 16, 242243.

Kiddy, C.A., 1977. Variation in physical activity as an indication of estrus in dairy cows. J. Dairy Sci.

60, 235243.

Kiestra, P.P., Icking, C., 1981. Milchmengenmegerat und Verfahren zum Messen der von einer Kuh im

Zuge des Melkens abgegebenen Gesamtmilchmenge. (Milkmeter and procedure for measuring the

total yield produced by a cow during milking) Offenlegungsschrift DE 3020161 A1.

Klein, R., Bothur, D., Rudovsky, H.-J., Preu, H., Lupfert, M., Lochner, W., 1985. Erste Erfahrungen

bei der Anwendung neuer Melkverfahren. (First experience with application of new milking

procedures). Tierzucht 39 (3), 128131.

Kremer, J.-H., Ordolff, D., 1992. Consequences of relating milking frequency to milk yield on milk

quality, milk production and behaviour of cows. In: Ipema, A.H., Lippus, A.C., Metz, J.H.M.,

Rossing, W. (Eds.), Proceedings of the International Symposium on Prospects for Automatic

Milking. Pudoc, Wageningen, The Netherlands, pp. 253260 EAAP publication No. 65.

Lake, J.R., 1987. A low maintenance milk conductivity sensor for detecting mastitis. In: Proceedings of

the 3rd Symposium on Automation in Dairying, Wageningen, Netherlands, pp. 129134.

Linzell, J.L., Peaker, M., 1975. Efficacy of the measurement of the electrical conductivity of the milk for

the detection of subclinical mastitis in cows: detection of infected cows at a single visit, Br. Vet. J.

131.

Ludington, D.C., Aneshansly, D.J., Pellerin, R.A., Guo, F., 1990. Adjustable speed drive two vacuum

milking system. American Society of Agricultural Engineers Paper No. 90-3556.

Maatje, K., Rossing, W., Garssen, G.J., Pluygers, H.G., 1983. Automation of Electrical ConductivityMeasurements during Milking. In: Proceedings of the Symposium on Automation in Dairying,

Wageningen, Netherlands, pp. 89100.

Maatje, K., Rossing, W., Wiersma, F., 1987. Temperature and activity measurements for oestrus and

sickness detection in dairy cattle. In: Proceedings of the 3rd Symposium on Automation in Dairying,

Wageningen, Netherlands, pp. 176184.

Machan, C.S., 1980. A cow on the move may be a cow in heat. Dairy Herd Management September,

5.

Marshal, R., Scott, N.R., Barta, M., Foote, R.H., 1979. Electrical conductivity probes for detection of

estrus in cattle. Trans. ASAE 22, 11451156.

Montalescot, J.B., 1981. Liquid-counter, especially a milk-counter, provided with a device for withdraw-

ing samples, French patent EP0023449.

Montalescot, J.B., 1987. Robotisation de la traite: Des Travaux deja bien avances. (Robotic milking:

research already has made good progress). Revue laitiere elevage 30 (3), 101 103.

Notsuki, I., Ueno, K., 1977. System for Managing Milking Cows in Stanchion Stool, United StatesPatent 4 010 714.

Ordolff, D., 1972. Eine neue Generation von Melkmaschinen. (A new generation of milking equipment).

Top Agrar 7, R11R12.

Ordolff, D., 1984. A system for automatic teat cup attachment. J. Agric. Eng. Res. 30 (1), 6570.

Ordolff, D., 1997. Experiments on automatic preparation of milk samples in connection with milking

robots. Comput. Electron. Agric. 17 (1), 133137.

Paul, W., Speckmann, H., 1979. Die Messung der Milchtemperatur als Mittel zur U8 berwachung der

Tiergesundheit und Steuerung des Milchentzuges. (Measurement of milk temperature for monitoring

animal health and controlling the milking procedure). Grundlagen Landtechnik 29 (6), 201.

Paul, W., Speckmann, H., Ihle, W., Roth, H., 1984. berwachung der Herzschlagrate bei Milchkuhen-

Sensorentwicklung und erste Ergebnisse. (Monitoring heart rates of dairy cows-sensor development

and first results). Grundlagen Landtechnik 35 (6), 182189.

Persson, L., Akesson, M., Lind, O., Malmqvist, A., Wiktorsson, H., O8 rberg, J., 1980. Anwandning av

Mjolktemperatur som Hjalpmedel vid Detektering av Brunst hos Kor. (Utilization of milk tempera-

ture as an aid for oestrus detection in cows). Sveriges Lantbruksuniversitet Uppsala, Institutionen for

husdjurens utfodring och vard Rapport 81.


24/25


Puckett, H.B., Spahr, S.L., Rodda, E.D., 1983. Real-time measurement of milk conductivity. In:

Proceedings of the Symposium on Automation in Dairying, Wageningen, Netherlands, pp. 101 114.

Rossing, W., Maatje, K., 1978. Automatic data recording for dairy herd management. In: Proceedings

of the International Symposium on Machine Milking, 17th Annual Meeting National Mastitis

Council, Louisville, KY, pp. 319327.

Rossing, W., Ipema, A.H., Kerkhof, J.A., Pluygers, H.G., Garsen, G.J., Maatje, K., 1983a. Micro-elec-

tronics in dairy herd management. In: Proceedings of the National Conference on Agricultural

Electronics Application, Agricultural Electronics 1983 and Beyond, Chicago, IL, vol. II, pp.

606613.

Rossing, W., Ipema, A.H., Maatje, K., 1983b. Actrons for measuring activity of dairy cows. In:

Proceedings of the Symposium on Automation in Dairying, Wageningen, Netherlands, pp. 127 134.

Rossing, W., Benders, E., Hogewerf, P.H., Hopster, H., Maatje, K., 1987. Practical Experience with

real-time measurements of milk conductivity for detecting mastitis. In: Proceedings of the Sympo-

sium on Automation in Dairying, Wageningen, Netherlands, pp. 138146.

Schalm, O.W., Noorlander, D.O., 1957. Experiments and observations leading to development of the

California-Mastitis-Test. J. Am. Vet. Med. Ass. 130, 199.

Scheidemann, B., 1990. Ein kartesisch arbeitender Roboter-Aufbau und Erfahrungen. (A cartesian

robot-structure and experiences). In: VDI/MEG Kolloquium Landtechnik, H. 9, Robotereinsatz in

der Landwirtschaft am Beispiel des Melkens, Dusseldorf, pp. 221 227.

Schlunsen, D., Paul, W., Speckmann, H., 1982. Erfassung der Milchtemperatur zur Herdenu-

berwachung. (Measurement of milk temperature for herd management purposes). Landbauforschung

Volkenrode Sonderheft 62, 171 173.

Schlunsen, D., Schon, H., Roth, H., 1987. Automatic detection of oestrus in dairy cows. In: Proceedings

of the Symposium on Automation in Dairying, Wageningen, Netherlands, pp. 166174.Schlunsen, D., 1983. Validity of different physiological parameters for automatic control of the udder

health. In: Proceedings of the Symposium on Automation in Dairying, Wageningen, Netherlands,

pp. 6978.

Schlunsen, D., 1985. Moglichkeiten der Fruherkennung von Krankheiten durch automatische Datener-

fassung unterschiedlicher physiologischer Parameter mit Hilfe rechnergestutzter Systeme. (Possibili-

ties for early detection of dieseases by automatic data recording of various physiological parameters

by computer based systems). Landbauforschung Volkenrode Sonderheft 75, 170 185.

Smith, J.W., Schultze, W.D., 1978. Automatic detection of Mastitis. In: Proceedings of the International

Symposium on Machine Milking, 17th Annual Meeting National Mastitis Council, Louisville, KY,

pp. 309318.

Spahr, S.L., Jones, L.R., Dill, D.E., 1988. Expert systems their use in dairy herd management. J.

Dairy Sci. 71, 879885.

Stanzel, H., 1977. Elektronische Programmsteuerung von Melkzeugen. (Programmed electronic controlof milking units). In: Semmler, K.-O. (Ed.), Probleme der modernen Melktechnik. (Problems of

modern milking technology), vol. 217. KTBL-Schrift, Munster-Hiltrup, pp. 64 75.

Street, M.J., Frost, A., 1990. A pneumatic milking robot structure, performance and first results. In:

VDI/MEG Kolloquium Landtechnik, H. 9, Robotereinsatz in der Landwirtschaft am Beispiel des

Melkens, Dusseldorf, pp. 188 201.

Thompson, P.D., Rodrian, J.A., 1983. Transducers for capture of activity data. In: Proceedings of the

Symposium Automation in Dairying, Wageningen, Netherlands, pp. 115126.

Tolle, A., Whittlestone, W.G., 1976. Grundlagen der Hygiene der Milchgewinnung. (Fundamentals of

hygiene of milking). Kieler Milchwirtschaftliche Forschungsberichte 28 (2), 81224.

Tolle, A., Heeschen, W., Hamann, J., 1977. Grundlagen einer systematischen Bekampfung der subklin-

ischen Mastitis des Rindes. (Fundamentals of systematic control of subclinical mastitis of cattle).

Kieler Milchwirtschaftliche Forschungsberichte 29 (1), 3103.

Torsius, A., 1987. Milking apparatus, European Patent Application EP 0 213 660 A1.

Troger, F., 1965. Verfahren und Vorrichtung zur Erzeugung der Melkbereitschaft, insbesondere bei

Kuhen. (Procedure and device to create readiness for milking, especially in cows), German Demo-

cratic Republic patent 41037.


25/25


Tsenkova, R.N., Yordanov, K.I., Shinde, Y., 1992. Near-infrared spectroscopy for evaluating milk

quality. In: Ipema, A.H., et al. (Eds.), Proceedings of the International Symposium on Prospects for

Automatic Milking. Pudoc, Wageningen, pp. 185192.

Verbrugge, J.K.J., Aurik, E.A., 1988. Movable accommodation or container in which is arranged

apparatus for automatic milking of an animal. Offenlegungsschrift 0 270 165 A1, Europ. Patentan-

meldung 87202238.9.

Williams, D.J.F., Yver, D.R., Gross, T.S., 1981. Comparison of estrus detection techniques in dairy

heifers. J. Dairy Sci. 64, 17381741.

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