Method and apparatus for automatically milking animals

In a method of automatically milking animals, such as cows, the milk obtained from each udder quarter is discharged through separate milk lines to a collector element. When the milk flow from one or more udder quarters has decreased to less than a threshold value, the vacuum in the teat cup or cups connected to the udder quarter is broken. When mastitis has been detected in an udder quarter and after the milk flow originating therefrom, possibly combined with that from one or more other udder quarters, has decreased to below said threshold value, the udder quarter or quarters involved are automatically stripped, either during a predetermined period of time or for receiving a predetermined quantity of milk, or until the milk flow has decreased to less than a second threshold value which is lower than said first threshold value.

FIELD OF THE INVENTION 
The present invention relates to a method of automatically milking animals, 
such as cows, in which the animals are milked by one or more milking 
robots, and in which milk obtained from an udder quarter is discharged to 
a collector element, such as a milk claw or a milk jar. 
BACKGROUND AND SUMMARY OF THE INVENTION 
Such constructions are known. But they may not always be satisfactory for 
the prevention of illnesses such as mastitis. It is thus an object of the 
present invention to prevent mastitis and other illnesses to the extent 
possible. To that end, if in an early stage an illness has been detected 
in an adder quarter and the milk flow has fallen to below a defined 
threshold value (D1), this udder quarter is automatically stripped, If so 
desired, this threshold value (D1) may be different for various animals. 
When the milk flow has fallen to below a predetermined threshold value, it 
is considered that the milking operation should cease; the udder quarter 
is assumed to have been more or less stripped at much as it should be. 
More specifically, to prevent mastitis, it is important for the milking 
operation to be stopped when the milk flow has become quite weak. If then 
the milking operation is continued, the teats may be irritated to such an 
extent that the risk of mastitis is increased. However, once mastitis has 
been detected in an udder quarter, it may be of importance nevertheless to 
continue milking. Therefore, once mastitis has been detected in an udder 
quarter and after the milk flow originating therefrom, possibly combined 
with that from one or more other udder quarters, has fallen to below 
aforesaid threshold value (D1), the udder quarter or udder quarters 
involved are automatically stripped. 
In a first method, when mastitis has been detected in an udder quarter and 
after the milk flow therefrom has decreased to less than said threshold 
value (D1), this udder quarter is stripped further for a defined time 
interval. In a second alternative method, when mastitis has been detected 
in an udder quarter and after the milk flow originating therefrom 
decreases to below said threshold value (D1), the udder quarter is 
stripped further until an additional, predetermined quantity of milk has 
been withdrawn from this udder quarter. In yet another feasible method, 
when mastitis has been detected in an udder quarter and after the milk 
flow originating therefrom decreases to below said threshold value (D1), 
the udder quarter is stripped further until the milk flow from this udder 
quarter falls below a second threshold value (D2), lower than the 
first-mentioned threshold value (D1). In this method, the second threshold 
value (D2) may depend on the extent to which mastitis has been detected. 
Another option is to continue the milking operation until all or 
substantially all the milk has been withdrawn from an udder quarter 
affected by mastitis. To discontinue the stripping operation it is 
sufficient to reduce the degree of vacuum in the relevant teat cup, it not 
being absolutely necessary for the teat cup to be disconnected or removed 
at the same time. The question as to which method is to be used, depends 
to a significant extent on whether the teat cups are individually 
disconnectable or can only be disconnected and removed collectively. In 
addition, it should be noted that the above method can be applied to each 
udder quarter separately or in pair, for example the two front udder 
quarters and the two rear udder quarters. The two front, and also the two 
rear udder quarters are comparable to each other to a significant extent 
in respect to their milk yield. It is possible that mastitis is detected 
in the joint milk flow from the two front or from the two rear udder 
quarters or from both. In this situation, after the milk flow originating 
from the two front or rear udder quarters decreases to below a first 
threshold value, the two udder quarters continue to be stripped further, 
although mastitis may have occurred in only one of the two udder quarters. 
According to the invention, a mastitis sensor may be incorporated in each 
of the milk lines, which causes a signal M to be derived in a computer, 
indicating that mastitis has occurred in a given udder quarter, while 
furthermore, with the aid of this signal M, a threshold value for the milk 
flow in the milk line connected to the udder quarter affected by mastitis 
is derived in the computer in accordance with the Booleam expression 
D=D1.M+D2.M. More in particular, a milk flow sensor is incorporated in 
each of the milk lines, each milk flow sensor supplying to the computer a 
signal S, indicating the quantity of the milk flow, the relevant milk line 
under a teat cup being closed as soon as the computer has determined that 
the milk flow S has decreased to less than the threshold value D. The 
aforementioned methods may, of course, also be combined. This combined 
method is then characterized in that, after mastitis has been detected in 
an udder quarter and after the milk flow originating therefrom has 
decreased to less than the said threshold value (D1), this udder quarter, 
depending on the progression of the milk yield versue time, is either 
stripped further during a predetermined time interval, or is stripped 
further until the milk flow from this udder quarter has fallen to below a 
second threshold value (D2), the second threshold value (D2) being lower 
than the first-mentioned threshold value (D1), or is stripped further 
until an additional, predetermined quantity of milk has been taken from 
this udder quarter. 
A mastitis detection which has proved to be reliable in actual practice, is 
obtained when milk conductivity sensors are used as mastitis sensors. The 
milk conductivity sensed in a milk line is compared to the milk 
conductivity, updated in a computer on the basis of a progressive weighted 
or non-weighted average of previous milking turns, of a relevant animal on 
the basis of this comparison it is ascertained whether the relevant udder 
quarter, after the milk flow originating therefrom has decreased to less 
than said first threshold value (D1), should or should not be stripped 
further. The decision of whether or not mastitis is assumed to be present, 
is animal-dependent; the milk conductivity last measured is compared to 
the historical data previously recorded in the form of a progressive, 
weighted or non-weighted average. On the basis of the said comparison, the 
computer can produce an attention signal, which can be displayed on a 
display screen and/or be printed, this attention signal indicating to what 
extent the last-measured milk conductivity exceeds that ascertained in the 
computer. On the basis of this attention signal, by means of a command 
manually entered into the computer or by means of a command already 
previously recorded in the computer, a relevant udder quarter can be 
stripped further or be stripped further at least during the subsequent 
milking turn as soon as it is learned that the milk flow in the relevant 
milk line has decreased to less than the first-mentioned threshold value 
(D1). In practice, this will mean that on the basis of the attention 
signal the farmer can make the decision further to strip the relevant 
udder quarter in, for example the subsequent milking turn, although such a 
command may have already been stored in the computer, so that at the 
proper instant the relevant udder quarter can be stripped still further. 
Instead of milk conductivity sensors, it is alternatively possible to 
incorporate filters in the milk lines, the mastitis detection then being 
based on resistance measurements. The filter has a higher resistance to 
the milk flow passing therethrough when this flow has been infected by 
mastitis and consequently is somewhat cloudy. 
Instead of stripping a mastitis-affected udder quarter further than is 
usually customary, a mastitis in its initial stage can also be 
counteracted by milking the animals more frequently. Hence, the invention 
also relates to a method of automatically milking animals, such as cows, 
in which the milk obtained per udder quarter is discharged through 
separate milk lines to a collector element, such as, for example, a milk 
claw or a milk jar, and in which, when the milk flow originating from one 
or more udder quarters has fallen to below a threshold value (D1), the 
degree of vacuum in the teat cup or cups connected to the udder quarter or 
quarters is reduced or eliminated, which method is then characterized in 
that, when mastitis has been detected in an udder quarter and after the 
milk flow originating therefrom, possibly combined with that from one or 
more other udder quarters, has decreased to below said threshold value 
(D1), the relevant animal is admitted a more times per 24 hours than other 
animals into the area arranged for automatic milking. 
When mastitis has been diagnosed for an animal, it may be important to 
prevent the animal, after having been milked, from mingling with the other 
animals. Therefore, according to the invention, it is possible that, after 
mastitis has been diagnosed in an udder quarter, the relevant animal is 
transferred to an isolation area contiguous to the area arranged for 
automatic milking. This isolation area may also be used are an area in 
which the animals can be isolated for other reasons. The isolation area 
may thus be used to separate animals to be inseminated or animals whose 
hoofs must be clipped. 
The isolation area can also serve for collecting animals which report to 
the milking robot to be milked again too early after their previous 
milking turns. When these animals have to wait for some length of time, it 
would not be wise to send them back to the pasture: it might then be too 
long before they would report again to the milking robot, so that the time 
elapsed between successive milking turns would be too long. The invention, 
therefore, further relates to an apparatus for automatically milking 
animals, including an area comprising a milking robot and arranged for 
automatic milking, characterized in that, contiguous thereto, there is 
provided an isolation area in which animals, which report to the milking 
robot at such an instant that it must be assumed that the quantity of milk 
to be supplied by them will be less than a desired value, are detained 
until they can indeed be milked. The isolation area can then be in 
connection with a pasture, so that animals can be admitted from the 
pasture into the isolation area, optionally via the area arranged for 
automatic milking, and animals which need not be detained for specific 
reasons can go from the isolation area to the pasture. 
Among the animals to be milked there may be "animals which are difficult to 
be milked automatically"; they may be animals having only three teats or 
animals with very unequal teat heights with such animals, it may happen 
that the milking robot does not succeed, or even cannot succeed--also 
after repeated efforts--in connecting the teat cups to the teats of the 
animals. A signal indicating this is usually provided, so that the farmer 
can then act to milk the animal, if due, himself. Since, however, the 
milking robot may be in operation for the full 24 hours, the farmer might 
find himself alerted at any moment during these 24 hours. According to the 
invention, this inconvenience to the farmer is avoided when the animals 
which are difficult to be milked automatically are detained in the 
isolation area for predetermined periods of time, such as nighttime, 
during which access to the milking area is to be denied to them. More in 
particular, the invention, therefore, also relates to an apparatus for 
automatically milking animals, including an area comprising a milking 
robot and arranged for automatic milking, characterized in that animals 
which are difficult to be milked automatically, such as those having only 
three teats, those having very unequal teat heights, etc., are denied 
access to the area arranged for automatic milking, for example, during the 
night, or are removed from this area without being milked if they had 
obtained access thereto in one way or another. More in particular, alarm 
means may be provided, with the aid of which it can be indicated that 
milking of the animal present in or at a milking compartment could not be 
accomplished because, for example, the milking robot cannot successfully 
connect the teat cups to the teats of the animal. Use of the alarm means 
can be avoided at least for animals which are difficult to be milked 
automatically during the periods of time that access to an area from which 
they can enter the milking compartment is denied to them. 
According to the invention, the number of animals transferred from the 
milking area to the isolation area will be updated in the computer. The 
number of animals present in the isolation area can be updated both in the 
computer and in counting means provided for the purpose at or near the 
entrance and/or exit of the isolation area. When the animals enter the 
isolation area from the milking area, this can be recorded directly into 
the computer; when, however, the animals are guided by the farmer via a 
further door from the isolation area or predetermined animals are led 
therein, then the farmer can further update the number of animals present 
in the isolation area with the aid of the counting means. When the number 
of animals present in the isolation area exceeds a predetermined value, 
then the farmer may be warned. 
Mastitis can not only be treated by further stripping of an udder quarter 
affected by mastitis and/or by more frequent milking of an animal, but 
also by rubbing an anti-mastitis ointment on at least the teat of the 
relevant udder quarter. The invention, therefore, also relates to a method 
of automatically milking animals, such as cows, characterized in that, 
when mastitis has been detected in an udder quarter, an anti-mastitis 
ointment is automatically applied, after milking, on at least the teat of 
the relevant udder quarter. 
The invention does not only relate to a method, but also to an apparatus 
for automatically milking animals, in which the afore-described method can 
be applied. The apparatus then includes teat cups and a collector element, 
such as a mild claw or a milk jar, to which receives the milk obtained 
from each udder quarter through separate lines, and a mastitis sensor and 
a milk flow sensor incorporated in one or more of these lines and, in 
addition, means are present for breaking or reducing the vacuum in the 
teat cups and/or means for disconnecting the teat cups. The apparatus is 
then characterized in that there is present a computer, which, in response 
to signals coming from the milk flow sensor and the mastitis sensor, 
applies a control signal to the said vacuum breaking or reducing means, 
when the milk flow in a relevant milk line decreases to below a 
mastitis-depending threshold value or when a predetermined time interval 
has elapsed after this milk flow has decreased to less than a fixed or 
udder quarter-dependent threshold value. As a result, the vacuum in a 
relevant teat cup is broken or sufficiently reduced the teat cups for 
disconnecting. More specifically, when the milk flow sensors used are of 
the type in which the through-flow of a given quantity of milk is 
indicated by means of electrodes, it is, in accordance with the invention, 
important for the milk flow sensors to be provided in the milk lines near 
the connection of the milk lines to the collector element. The milk lines 
themselves then act as a kind of buffer, via which the milk obtained from 
the udder quarters is supplied in a pulsed mode. When at consecutive 
pulsed strokes less milk is fed through the line to a milk flow sensor, it 
takes a longer period of time before the volume between the two electrodes 
is filled with milk and the period of time between the signals supplied by 
the electrodes will increase. This period of time, which becomes longer 
towards the end of the milking operation, is a measure of the rate of milk 
flow. The predetermined threshold values then are in a direct relationship 
with the length of the time interval between consecutive signals produced 
by the electrodes. 
Furthermore, according to the invention, a shut-off element for the milk 
lines connected to the teat cups may be provided under each of the teat 
cups, each of the shut-off elements closing a milk line after said control 
signal has been provided. Furthermore, according to the invention, a 
pulsator is usually provided for producing in each of the teat cups a 
pulsating vacuum, which in the relevant teat cup is broken after the said 
control signal has been applied, by admitting ambient pressure therein. 
The afore-mentioned method can more in particular be applied in an 
advantageous manner in an above-described apparatus, which is not only 
arranged for automatic milking, but which is also provided with a milking 
robot for automatically connecting the teat cups to the teats of an animal 
to be milked and automatically disconnecting same, as soon as the milk 
flow in a given milk line has decreased to less than a mastitis-depending 
threshold value, preset in the computer, or as soon as a predetermined 
time interval has elapsed after the milk flow has decreased to below a 
fixed or udder quarter-depending threshold value. In this situation, the 
milking robot may comprise means for, when mastitis has been detected in 
an udder quarter after milking, automatically applying an anti-mastitis 
ointment on at least the teat of the relevant udder quarter. 
According to the invention, the above-described apparatus may further 
include both an area arranged for automatic milking and an isolation area 
contiguous thereto, to which latter area the animals can be transferred 
for special reasons, such as because mastitis has been detected, or 
because the animals are to be inseminated, or because the hoofs of the 
animals must be clipped, etc. In or near this isolation area there may be 
arranged counting means, by means of which the number of animals present 
in the isolation area can be updated manually, more in particular when the 
animals are led into or from the isolation area via a separate passage. 
These counting means may be connected to a computer for a computerized 
updating of the number of animals present in the isolation area as 
indicated by the counting means, when the animals enter the isolation area 
from the milking area.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a plan view of a shed or housing 1, in which a feeding area 2 is 
present which extends centrally in the longitudinal direction thereof. At 
both sides of feeding area 2, a plurality of cubicles 3 are located along 
substantially the overall length of housing 1 along the sides of its outer 
wall and, along the sides of feeding area 2 a plurality of feeding 
stations 4 located. Via doors 5 and 6 in shed 1, fodder in the form of hay 
can be transferred by means of a tractor driving into feeding passage 2 to 
feed channels and/or concentrate to feeding troughs for the feeding 
stations 4. Cubicles 3 and feeding stations 4 are arranged so that 
sufficient room remains for the animals to walk between the cubicles and 
the feeding stations, and so that they can move about and exercise to a 
sufficient extent and basically can walk around the shed. Near a shorter 
side of the shed is a milking area or compartment 7, in which a machine or 
apparatus for automatically milking animals is positioned. This milking 
machine includes a milking robot 8 for automatically connecting teat cups 
to the teats of an animal to be milked and subsequently disconnecting 
then. Between milking area 7 and the nearby side of shed 1 is a computer 
area 9, in which a computer 10 is located together with all the equipment 
that is part of the milking apparatus but is not disposed in milking area 
7 proper. The milking compartment 7 has an entrance door 11 and two exit 
doors 12 and 13. The animals can enter the milking area from the exercise 
area via the door 11, whilst the animals can enter the exercise area again 
from the milking area via the door 12. As soon as an animal has entered 
the milking area from the exercise area or, via the exercise area, from 
the pasture, the animal's identity is ascertained in the customary manner. 
By means of the cow recognition system used therefor, assess is obtained 
to a data file present in the computer of the system for this animal. 
Recorded in this file inter alia is how much time has elapsed since her 
previous milking turn. From the subsequently established time differences 
between the moment when an animal enters the milking compartment, or at 
least reports at the milking compartment (in case the animal is identified 
prior to entering same), and the previous milking turn, an average value 
of these time differences can be determined. Preferably, this is done on 
the basis of a progressive average, based on each milking turn over say 
the last seven days. Furthermore the spreading in this average is 
determined. The said average value and the spreading therein are recorded 
in the memory file for the relevant animal and serve as a basis for a 
possible warning or placing the animal on an attention list, when an 
animal does not report in time at the milking compartment. When since the 
previous milking turn there has elapsed a period of time corresponding to 
the said average value plus a certain additional time determined by the 
said spreading without the animal having reported, then the animal must be 
brought in to be milked. 
Next to milking area 7 there is an isolation area 14, which can be reached 
from the milking area via door 13. In addition, isolation area 14 is 
accessible via doors 15 and 16. In area 14, animals can be separated from 
the animals present in the exercise area of shed 1. This may be necessary 
because the animals have an udder shape that the teat cups cannot be 
connected automatically, because they are to be inseminated or because 
their hoofs are to be clipped, in which event the farmer can lead the 
animals via door 15 into isolation area 14, but also if mastitis has been 
detected in animals present in the milking area 7, those animals are then 
led from there via door 13 into isolation area 14 instead of into the 
exercise area of shed 1. The farmer can fetch animals from isolation area 
14 via door 16. Using computer 10, which is further used for controlling 
the automatic milking procedure and the automatic connecting of the teat 
cups to the teats and disconnecting same therefrom, and also for 
performing all possible actions that are also of importance to the milking 
operation, the number of animals which are led from milking area 7 to 
isolation area 14 can be updated. When, however, the farmer himself leads 
animals into the isolation area via the door 15, or removes animals 
therefrom via the door 16, then the number of animals in the isolation 
area, as recorded in computer 10, will not correspond to the actual 
number. To prevent this error, counting means 17 are provided which are 
connected to computer 10. These counting means are preferably disposed 
near doors 15 and 16 and can be operated manually by the farmer. When the 
farmer leads an animal via one of doors 15 or 16 into the isolation area, 
then, by operating counting means 17, he can cause the number of animals 
indicated thereby to correspond to the actual number. Likewise, when he 
fetches an animal from isolation area 14 via one of the doors 15 or 16 the 
farmer can adjust, by operating the counting means, the number of animals 
present in the isolation area, so that, since counting means 17 are 
connected to the computer 10, the correct number of animals present in the 
isolation area is updated at all times in computer 10 and, if so desired, 
can be displayed on a display screen provided on the counting means. When 
in the absence of the farmer too many animals are passed from milking area 
7 to isolation area 14, an alarm can be triggered to warn the farmer that 
the number of animals in isolation area is too high. 
As has already been stated before, there may be present an isolation area 
for animals which have such an udder shape that the teat cups cannot be 
connected automatically. After these animals have been identified, they 
can be passed on to the isolation area, without the milking robot trying 
to connect the teat cups. Also animals, whose connection of the teat cups 
has failed even after repeated efforts, can be guided via the milking 
compartment to the isolation area, certainly during the so-called curfew 
times, such as during the night. The animals guided to the isolation area 
for the above reasons should be subsequently milked. For this purpose they 
are guided from the isolation area to the milking compartment, where the 
teat cups usually will have to be connected manually. To do this, the 
dispositions of various gates or doors into and from milking compartment 7 
and isolation area 14 are represented in FIGS. 3A to 3E. In these Figures, 
the milking area is indicated again by reference numeral 7 and the 
isolation area by reference numeral 14. The entering and leaving of these 
areas is effected by means of, preferably computer-controlled, doors 28, 
29, 30 and 31. In position of the doors as shown in FIG. 3A, an animal can 
enter the milking compartment 7 from the exercise area in the shed; doors 
28 and 29 are subsequently closed (see FIG. 3B). When thereafter the 
connection of the teat cups fails or connection is not attempted due to 
the deviating udder shape, then door 30 is opened and the animal is guided 
to isolation area 14 (see FIG. 3C). Then door 30 is closed. When in this 
manner a certain number of non-automatically to be milked animals have 
been collected in the isolation area, then these will be admitted from 
isolation area 14 to the milking compartment in the presence of the farmer 
and at a moment to be decided by him. After the door 29 has opened (see 
FIG. 3D), an animal can enter the milking compartment from the isolation 
area, after which the door 29 is closed again, the animal is subsequently 
milked and dismissed from the milking compartment by opening doors 30 and 
31 (see FIG. 3E) and guided to the exercise area of the shed. Then doors 
30 and 31 close, while the door 29 is opened again in order to admit the 
next animal from the isolation area to the milking compartment. 
The apparatus for automatically milking animals, which is partially and 
schematically shown in FIG. 2, includes teat cups 18 which are 
automatically connected to the teats of an animal to be milked by milking 
robot 8. Each of the milk lines 19 connected to teat cups 18 extends 
individually into a milk jar 20, from which, each time when a 
predetermined quantity of milk is received therein. The milk is pumped by 
means of a pump 22 via a shut-off device 21 into a line 23 leading to a 
milk tank (not shown). Under teat cups 18, each milk line 19 includes a 
shut-off device 24. Also a mastitis sensor 25 and a milk flow sensor 26 
are incorporated in each of the milk lines 19. Milk flow sensors 26 are 
accommodated in milk lines 19 near the region where these milk lines end 
in the milk jar 20. FIG. 2 shows computer 10 which is also shown in FIG. 
1. Signals S from individual milk flow sensors 25 are applied to this 
computer 10, each of these signals S being indicative of the milk flow in 
a relevant milk line 19. In addition, signals M supplied by each of the 
mastitis sensors are transmitted to computer 10. In the present 
embodiment, the mastitis sensors are milk conductivity sensors. The 
signals supplied by these sensors, which signals are a measure of the 
conductivity of the milk, are compared in the computer 10 to progressive, 
weighted or non-weighted average of the milk conductivity recorded during 
previous milking turns, whereupon, when the last-measured milk 
conductivity exceeds the progressive, weighted or non-weighted average to 
an excessive extent, an attention signal is displayed on display screen of 
the computer 10, on the basis of which signal the farmer can decide 
whether or not it is a matter of mastitis and if measures to counteract it 
must be taken. These data, and other data relevant to the milking of the 
animal or to her health, can not only be displayed on the display screen 
of the computer, but also be shown on attention lists to be printed out or 
even on a display screen to be arranged in the shed or elsewhere in the 
farm, so that the farmer can see the relevant data from a distance and at 
a single glance, without him having to strain his eyes on a computer 
display screen. By keying-in an affirmation in computer 10 a signal is 
received by computer 10 that it is indeed a matter of mastitis. This 
signal can, of course, also be produced automatically when the 
last-measured milk conductivity has exceeded the progressive, weighted or 
non-weighted average recorded in the computer by a predetermined extent. 
In computer 10, threshold values D1 and D2 may have been recorded in a 
program for the milk flow in the lines 19, or these threshold values may 
be entered via a keyboard. In the computer 10, a threshold value D is 
derived from the signal M and the threshold values D1 and D2, for which it 
holds that, as soon as the signal S from a milk flow sensor 26 has 
decreased to less than threshold value D, computer 10 produces a control 
signal. This control signal can be applied to a shut-off device 24 for 
closing the relevant milk line and for thereafter breaking the vacuum of 
the relevant teat cup and for optionally disconnecting the teat cup 
immediately thereafter. For the benefit of the milking operation there is 
present a pulsator 27, which is controlled by computer 10 and which 
produces a pulsating vacuum in each of the teat cups. After the said 
control signal has been applied, pulsations in the relevant teat cup to 
cease by admitting air at ambient pressure therein. The threshold value D, 
such as it is established in the computer 10, satisfies the Boolean 
expression D=D1.M+D2.M. In other words, in computer 10 there is determined 
a mastitis-dependent threshold value for the milk flow in a milk line 19, 
and as soon as the milk flow has decreased to a level below the 
predetermined threshold value D, milking of the relevant udder quarter is 
to be stopped. Since the second threshold value, i.e. the threshold value 
which holds for the case when mastitis has been found in an udder quarter, 
is less than the first threshold value, the relevant udder quarter is 
milked for a longer period of time than would be the case when no mastitis 
was detected in an udder quarter. 
Instead of the second threshold value D2 it is also possible to utilize a 
predetermined time interval, which starts after the milk flow in the 
relevant line has decreased to less than the threshold value D1, for 
stripping the udder quarter. 
The invention is not limited to the embodiment described in the foregoing, 
but includes further modifications, insofar as they are within the scope 
of the accompanying claims.