RELATED ART In a dairy farm with machine milking it is known to separate milk such as directing milk with high cell count or milk of low quality to a separate container such as a waste container.

A method of milking animals is known from EP 0628244, wherein milk can be collected in different storage containers after having been separated according to quality and/or composition, whereby the milk can be collected depending on the albumen or fat content, the colour, the blood content, the light absorption, the cloudiness or contamination of the milk. A distinction can also be made between milk from an individual animal depending on the course of the lactation period. In addition, the milk can be collected after separation depending on the somatic cell count of the milk or between milk obtained during the initial stage of the milking operation and that during the further course thereof.

SUMMARY OF THE INVENTION It is known that melatonin is a hormone that regulates the diurnal rhythm and the season rhythm, aid the immune defence, and is an antioxidant. Therefore melatonin is a coveted hormone that is desirable to market.

Since the melatonin hormone comes naturally in milk, it is possible to sell milk products marketed with the advantages of melatonin. With the realization that an animal produces milk with a higher content of melatonin during the night than during the day, milk products could, without additive, have an enhanced content of melatonin. Thus, products can be sold marketed as natural products containing an enhanced amount of melatonin.

The production of melatonin is also related to darkness besides the time of day or night. Therefore an animal (or rather its hormone production) could be deluded into believing that it is night by keeping the animal in a dark place.

Accordingly, it is an object of the present invention to provide a method of milking an animal, which separates milk depending on its melatonin content.

This and other objects are according to one aspect of the present invention attained by a method as claimed in claim 1.

Advantageously, prior to separating the milk the animal is identified. Preferably, individual information of the identified animal is utilized in controlling the separation of milk.

A further object of the present invention is to provide an arrangement for milking an animal, which separates milk depending on its melatonin content.

This object is according to a second aspect of the present invention attained by an arrangement as claimed in claim 7.

Advantageously, the animal to be milked is identified and individual information of the animal is stored in a control device.

According to a third aspect of the present invention an arrangement is provided as claimed in claim 12.

According to a fourth aspect of the present invention an arrangement is provided as claimed in claim 13.

More advantages and features of the invention will be apparent from the description below.

SHORT DESCRIPTION OF THE DRAWINGS The invention will be described closer below with reference to Figs. 1-2, which are only shown in order to illustrate the invention and shall therefore in no circumstances limit the same.

Fig. 1 shows schematically a first embodiment of the present invention.

Fig. 2 shows schematically a second embodiment of the present invention.

PREFERRED EMBODIMENTS In the following description, for the purpose of explanation and not limitation of the invention, specific details are given, such as particular applications, techniques, etc., in order to give a thorough understanding of the invention. It shall, however, be apparent for the man skilled in the art that the invention may be practiced in a manifold of other forms than these. In other instances, detailed descriptions of well-known methods and arrangements are omitted so as not to obscure the

description of the present invention with unnecessary details.

In order to separate milk, drawn from an animal, depending on its melatonin content, a control device is used to keep track of the time of day or night. Further the control device keeps track of individual animals and their respective melatonin content and other related information such as if the milk has high cell counts and/or if the milk has low quality. The control device controls a divider element, which preferably is a tree-way valve if two separate containers are used. The milk is drawn from the teats of the animal, conveyed through separate milk lines, intermediately collected in a milk meter, and separated in the divider element. Milk containing melatonin levels above a threshold, preferably milked during the night, is stored in a separate container and other milk with melatonin levels below a threshold is stored in another container. An animal identification unit may be provided to identify the animal and forward this identity to the control device. A sensor at the milk meter may be utilized to detect the composition of the milk and forward this information to the control device.

Referring now to fig. 1, a first embodiment of an arrangement for milking an animal, such as a cow, a goat, a sheep, or the like, has four teat cups 1 of which only one is fully shown for the sake of simplicity. Each such teat cup 1 may be of any conventional type and is independently of each other connected to a respective milk line 9. A milk line comprises a milk meter that receives milk, measures it, and forwards the milk. Each milk line 9 may independently of each other be connected to two different storage containers 6,6'via a respective three-way valve 5. This arrangement is a part of an automatic milking machine, schematically shown as 7. It shall be appreciated

that the milking machine may comprise any necessary or desired equipment known in the art.

The containers 6,6'are shown as two separate containers, but could of course be one tank with separate spaces.

In the description below the function of only one of the four teat cups with its respective milk line will be described to simplify the description of the invention.

The three-way valve 5 directs milk from the animal to different containers 6,6', and is controlled by a control device 4. The control device controls the valve 5 depending on the time of day or night. Milk from an animal milked during the night is directed to a first container 6 and milk from an animal milked during the day is directed to a second container 6'. The control device 4 comprises a clock that keeps track of the time of day or night.

It is possible that different animals or different animal varieties have different content of melatonin in their milk, some possibly of such low content that the milk there from is not desirable to collect separately. For instance, a good milker probably has a lower content of melatonin than a poor milker. Alternatively, an animal could have milk with high cell count or milk of low quality, which preferably is collected separately.

By using an identification unit 2 that identifies an animal to be milked, it is possible to keep a flag for each animal to be milked in the control device 4 that indicates if milk from that animal should be possible to direct to the first container 6. If the flag indicates that it is an animal with possibly high content of melatonin the clock is checked to determine the time of day or night and the milk is collected depending on the time of day or night.

Alternatively, milk having high cell count or of low

quality is separated and collected in a further container, not shown in Fig. 1.

It is also possible that different animals have their respective maximum and minimum content of melatonin during different times round the clock. By use of the identification unit 2 it is possible to supply each animal with its own timetable in the control device 4, said timetable indicating when milk should be collected in container 6 and when milk should be collected in container 6'. I. e. one animal milked at a certain time of day or night may have its milk directed to the first container 6, and another animal milked at the same time of day or night may have its milk directed to the second container 6'.

A measurement unit 3 may be provided, which detects the composition of the milk and forwards composition information to the control device 4.

Next, a method of milking an animal will be described, still with reference to Fig. 1. When an animal enters the automatic milking machine 7 it will be milked. Teat cups 1 are attached to the teats of the animal, milk is drawn from the teats of said animal, the milk is separated in a divider element 5 depending on the time of day or night, and the milk is collected in separate containers 6,6'.

The control device 4 keeps track of the time of day or night, and controls the divider element 5 depending thereon. Milk that is collected during the night contains a higher content of melatonin than milk that is collected during the day. Therefore milk that is collected during the night is directed to a container 6 separate from other milk.

In order to collect milk having an increased content of melatonin in the separate container 6 the animal is

identified by means of the identification unit 2. The identification of the animal is transferred to the control device 4 and a flag therein indicates if this particular animal has a sufficiently high content of melatonin in which case the time of day or night is checked to determine if the milk is to be directed to the separate container 6 and otherwise the milk is not directed to the separate container 6.

It is here also possible to have a further container for directing milk depending on other reasons, such as if the milk has high cell count or is of low quality.

A further way to raise the content of melatonin in the separate container 6 is to associate an individual clock to each animal to be milked. By use indications on what time of day or night when the respective animal has its highest content of melatonin in its milk, it is possible to only direct milk with a content of melatonin over a certain threshold based on the time of day or night for each individual animal.

In order to detect at which times an animal has its highest content of melatonin in its milk the measurement unit 3 detects the melatonin and transfers the information to the control device 4. The control device 4 adds the measured content to a database that is used in control of the tree- way valve 5.

A second embodiment of the present invention will now be described with reference to Fig. 2. In a simplified arrangement a milk meter 8 common to four teat cups 1 is utilized. Since milk from the different teats of the animal is mixed, one divider element 5 is sufficient to separate the milk into different containers 6,6'. As regards other features the arrangement corresponds with the first embodiment.

An alternative way of separating melatonin is to in situ measure the melatonin content of the milk with the measuring unit 3. The result of the measurement indicates to the control device 4 how to direct the milk by controlling the three-way valve 5.

The present invention has been described as separation of melatonin depending on the time of day or night, but is also applicable to separation of other elements depending on the time of day or night.

The present invention solves problems associated with known art. It is, of course, not limited to the embodiments described above and shown in the drawings, but may be modified within the scope of the appended claims.