METHOD OF MILKING ANIMALS

Abstract: In a milking process the animal is stimulated during a stimulation phase (I) for initiating the animal to let down milk in the udder, while a relatively small milk flow is achieved. During a subsequent main milking phase (II) the animal is treated to eject a relatively large milk flow. The stimulation phase is ended and the main milking phase is started when at least one monitored milking variable reaches a predetermined value. According to the invention the milking variable relates to the milk quantity extracted from the animal. Further milking variables may be monitored such as milk flow and the time of the stimulation phase, so that the stimulation phase is ended when any of the monitored milking variables reaches a predetermined value. Hereby the duration of the stimulation phase can be adapted to the individual needs of the animals.

Description: Method of milking animals The present invention relates to a method of milking an animal, in which the animal initially is stimulated during a stimulation phase to initiate the animal to let down milk in the udder, while a relatively small milk flow from the animal's teats is achieved. During a subsequent main milking phase of the milking the animal is treated to eject a relatively large milk flow from the animal's teats. At least one milking variable is monitored during the stimulation phase, the latter being ended and the main milking phase being started when said milking variable reaches a predetermined value. A cow to be milked will already at the preparation of her for milking be stimulated by sound, sight and sensing impressions, which will cause the cow's muscles around the milk passages in the udder and the teats to relax, so that the milk passages are expanded. In conse- quence the quantity of milk, about 0,5 - 2 kg, which already exists in the cisterns of the udder can easily be mechanically milked. In cows which respond relatively strongly to stimulation the relatively light stimulation caused by the preparation of the cow for milking has the consequence that the milk quantity which is enclosed in the alveoli in the udder is released and is given down into the udder cisterns. More specifically the stimula¬ tion of the cow activates the hormone oxytocine which affects the alveoli to contract so that the milk is pressed out. However, cows which respond relatively weakly to stimu¬ lation have to be more intensively stimulated during the initial stimulation phase, in order to activate the oxytocine. It is known to achieve such an intensive stimulation by massaging the udder and teats with the aid of hands, brushes or liquid jets, or by influencing the teats to electrical impulses or pressure pulses of varying intensity having high or low frequency. Thus, some cows which are easy to stimulate may be fully prepared for milking already after a few seconds of stimulation, while other cows which are difficult to stimulate may need to be intensively stimulated at least one minute to get fully prepared for milking. In average, however, it takes less than a minute of inten¬ sive stimulation before the effect of oxytocine results. Thereafter the oxytocine normally is effective during a time of four to seven minutes. Therefore the milking should be finished during this time, because after that the cow does not cooperate actively. To achieve a large milk flow from the cow's udder and thereby a rapid milking of the udder while the oxytocine is effective, a conventional milking machine exposes the cow's teat tips to a relatively strong milking vacuum, usually about 40-50 kPa. However, this strong milking vacuum gives rise to the problem that the teats are treated ungently initially during the milking, when the milk flow is small or non-existing, which may result in discomfort and even pains to the cow. This may lead to that the hormone adrenaline is secreted and makes continued milk extraction difficult. Many modern milking machines avoid this problem by exposing the teat tips to a relatively weak, for the teats careful milking vacuum during the stimulation phase and switches to the stronger milking vacuum when the main milking phase begins. It is known to monitor some milking variable during the stimulation phase and to finish the stimulation phase in response to said milking variable, when the latter reaches a predetermined value. Thus, US-A-3.754.532 describes a milking machine which in response to the milk flow reaching a predetermined value switches between a careful milking vacuum acting during the stimulation phase and a strong milking vacuum acting during the main milking phase. In this case the pre- determined value of the milk flow is chosen relatively small: 0,2 kg/minute. US-A-4.391.221 describes a milking machine which in response to the lapse of a predetermined time period switches between a high frequency pulsation of the teats, acting during the stimulation phase, and a low frequency pulsation, acting during the main milking phase. US-A-4.011.838 describes a milking machine which is adapted to finish the stimulation phase in response to both the milk flow and the lapse of a predetermined time period. Thus, the stimulation phase is ended when the milk flow reaches a predetermined value provided that this occurs before the lapse of the predetermined time period. Also in this case the predetermined value of the milk flow is chosen relatively small; 0,2 kg/minute. Also when milking a cow which is difficult to stimulate, a milk flow of 0,2 kg/minute may be achieved before the cow is completely stimulated, since there is already a certain available amount of milk in the udder cisterns. To make sure that the cows which are difficult to stimulate are satsifactorily stimulated before the stimulation phase is ended, the predetermined value for the milk flow could be increased from the usual 0,2 kg/minute to for instance at least 1 kg/minute. However, in such a case the problem arises that the stimulation phase may be unnecessary long for the majority of cows which are easy to stimulate, so that the milking time for these is prolonged. The object of the present invention is to provide a method of milking animals by means of which the duration of the stimulation phase is better matched to the indi¬ vidual stimulation needs of the animals, compared to known milking methods. This object is obtained by a method of the kind initially described, which is characterized in that said milking variable is the milk quantity extracted from the animal. Hereby the advantage is obtained that the stimu¬ lation phase with certainty can be made relatively short for animals which are easy to stimulate and relatively long for animals which are difficult to stimulate, since extracted milk quantity constitutes a clear indication on how prepared the animal is for milking. At least two milking variables are suitably monitored, the stimulation phase being ended when one of said two milking variables reaches a predetermined value. One of the milking variables of course is the milk quantity extracted from the animal while the other milking variable may be the milk flow from the animal's teats, or alternatively the time from the beginning of the stimulation phase. Hereby, the duration of the stimu¬ lation phase can be accurately adapted to the stimula¬ tion needs of the individual animal. Preferably a plurality of milking variables are monitored, a first milking variable of which is the milk quantity extracted from the animal, a second milking variable of which is the milk flow from the animal's teats, and a third of which is the time from the beginning of the stimulation phase. The stimulation phase is finished when one of the milking variables reaches a predetermined value. Hereby the accuracy of the duration of the stimulation phase for the needs of the individual animals can be further increased. Besides monitoring the above mentioned first, second and third milking variables of course further milking variables may be monitored, for instance the fat content of the milk, the conductivity of the milk etc. As to cows, suitable predetermined values for the milking variables to be monitored are dependent on several different factors, such as breed, lactation status, milk yield, milking times per day, type of milking machine used, etc. The predetermined values for the milking variables must therefore be determined by means of experiments. Nevertheless, in general for cows the predetermined value of the milk quantity is chosen in the range of 0,2 - 2,0 kg, preferably 0,4 - 1,0 kg, the predetermined value of the milk flow in the range of 0,5 - 2,5 kg/minute, and the predetermined value for the time of the stimulation phase in the interval of 30 - 100 seconds. During the stimulation phase the animal may advan¬ tageously be stimulated by exposing the animal's teats to pulses having a frequency of at least 2 Hz, pre- ferably at least 3 Hz. This relatively high pulsation frequency, normal pulsation frequency during the main milking phase is usually 1 Hz, has the consequence that the teatcup liners in the teatcups of the milking machine do not open completely, whereby the teatcup liners maintain a good frictional engagement with the teats even if the milk flow is small. As a result the teatcups are prevented from crawling upwards on the teats during the stimulation phase to positions which are more unfavourable for the extraction of milk. This is especially advantageous when the teats are exposed to full milking vacuum during the stimulation phase as well as the main milking phase. The invention is described more closely in the following with reference to the accompanying drawings, in which figure 1 shows a milking machine for milking cows according to the method of the present invention, figure 2 is a diagram which shows the variation of the milk flow Q during milking of a cow, and figure 3 is a diagram showing the pressure variations P in a teatcup of the milking machine according to figure 1, when a cow is milked. In figure 1 there is shown a milking machine comprising a milking means 1, for instance of the type HARMONY™, with four teatcups 2, in which teatcup liners 3 are mounted (only two teatcups are shown) . Each teatcup liner 3 has an interior milk conducting passage 4 and forms with the enclosing wall of the teatcup 2 a pulsation chamber 5. A teatcup claw 6 is connected to the teatcup liners 3 via four short milk hoses 7, and to the pulsation chambers 5 via four short pulsation hoses 8. Via the teatcup claw 6 the short pulsation hoses 8 are connected in pairs to two long pulsation hoses 9, 10, which extend upwardly from the teatcup claw 6 to a battery operated electronic pulsator 11. The pulsator 11 is connected to an air pipeline 12, the interior of which is exposed to an underpressure generated by a vacuum source (not shown) . The four short milk hoses 7 are via the teatcup claw 6 connected to a long milk hose 13, which extends upwardly from the teatcup claw 6 to a milk conduit 14, the interior of which communicates with said vacuum source. In the milk hose 13 there is a flow meter 15 for sensing the milk flow. A control unit 16, is connected to the flow meter 15, the pulsator 11 and a timer 17 via respective signal conduits 18, 19 and 20. The control unit 16 is adapted to control the pulsation frequency of the pulsator 11 in response to input data from the timer 17 and the flow meter 15. The combination of the control unit 16 and the timer 17 may for instance be of the type ALPRO™. The milking machine functions in the following way: The teatcups 2 are applied on a cow to e. milked. During an initial stimulation phase I of the milking the control unit 16 controls the pulsator 11 so that the latter alternates between atmospheric pressure and vacuum having a high frequency of 5Hz. Thus, the teatcup liners 3 are vibrated at the same high frequency, which results in an intensive stimulation of the cow's teats, see figure 2 and 3. With the aid of the timer 17 and the flow meter 15 the control unit 16 monitors the milk quantity extracted from the cow, the actual milk flow through the milk hose 15 and the time which has lapsed since the beginning of the stimulation phase I. The control unit 16 ends the stimulation phase I by switching the pulsator 11 from 5 Hz to a normal frequency of 1 Hz, when any of the following three conditions are fulfilled: The milk quantity amounts to 0,6 kg. The milk flow amounts to 1,7 kg/min. - The stimulation phase I has lasted for 70 seconds. In the diagram according to figure 2 there is shown a transition point of time a between the stimulation phase I and a main milking phase II of the milking, during which the pulsator 11 is operated at a normal frequency of 1 Hz. The transition point of time a thus is comple¬ tely individual for a cow to be milked and may be varied with the milking occasions for said cow. The predeter¬ mined values for the milk quantity, the milk flow and the time from the beginning of the stimulation phase have been determined by means of experiments so that when milking a herd of cows the control unit 16 switches the pulsator 11 to the normal pulsation frequency of 1 Hz in response to the milk quantity reaching a pre- determined quantity value during the majority of the milking operations, to the lapse of a predetermined time value during a small number of the milking operations, and to the milk flow reaching a predetermined flow value during the remaining milking operations. As a result from tests in which cows have been milked according to the present invention, the above described milking machine has shortened the total milking time by up to 10 %, as compared with conventional milking machines which end the stimulation phase only in response to the milk flow amounting to 0,2 kg/minute. Alternatively, the milking vacuum may be decreased, which gives an unchanged total milking time, but a more careful teat treatment and a larger milk yield as positive results. The method according to the invention is well suited for automatic milking machines, which are adapted to automa¬ tically attach teatcups, milk and detach the teatcups.

Claims: Claims 1. A method of milking an animal, in which the animal initially is stimulated during a stimulation phase ( I ) for initiating the animal to let down milk in the udder, while a relatively small milk flow is achieved from the animal's teats, the animal is treated during a subse¬ quent main milking phase (II) to eject a relatively large milk flow from the animal's teats, and at least one milking variable is monitored during the stimulation phase, the stimulation phase being ended and the main milking phase being started when said milking variable reaches a predetermined value, c h a r a c t e r i ¬ z e d i n that said milking variable is the milk quantity extracted from the animal. 2. A method of milking an animal, in which the animal initially is stimulated during a stimulation phase (I) for initiating the animal to let down milk in the udder, while a relatively small milk flow from the animal's teats is achieved, the animal is treated during a subsequent main milking phase (II) to eject a relatively large milk flow from the animal's teats, and at least two milking variables are monitored during the stimula- tion phase, the stimulation phase being ended and the main milking phase being started when any of said milking variables reaches a predetermined value, c h a r a c t e r i z e d i n that a first and a second milking variable of said at least two milking variables is the milk quantity extracted from the animal and the milk flow from the animal's teats, respectively. 3. A method of milking an animal, in which the animal initially is stimulated during a stimulation phase (I ) for initiating the animal to let down milk in the udder, while a relatively small milk flow from the animal's teats is achieved, the animal is treated during a subsequent main milking phase (II) to eject a relatively large milk flow from the animal's teat, and at least two milking variables are monitored during the stimulation phase, the stimulation phase being ended and the main milking phase being started when any of said milking variables reaches a predetermined value, c h a r a c ¬ t e r i z e d i n that a first and a second milking variable of said at least two milking variables is the milk quantity extracted from the animal and the time from the beginning of the stimulation phase, respec¬ tively. 4. A method of milking an animal, in which the animal initially is stimulated during a stimulation phase (I ) for initiating the animal to let down milk in the udder, while a relatively small milk flow from the animal's teats is achieved, the animal is treated during a subsequent main milking phase (II) to eject a relatively large milk flow from the animal's teats, and a plurality of milking variables are monitored during the stimula¬ tion phase, the stimulation phase being ended and the main milking phase being started when any of said milking variables reaches a predetermined value, c h a r a c t e r i z e d i n that a first, a second and a third milking variable of said plurality of milking variables is the milk quantity extracted from the animal, the milk flow from the animal's teats and the time from the beginning of the stimulation phase, respectivel . 5. A method according to claim 2 or 4, c h a r a c ¬ t e r i z e d i n that the predetermined value of the milk flow is chosen in the range of 0,5 - 2,5 kg/minute when a cow is milked. 6. A method according to claim 3 or 4, c h a r a c ¬ t e r i z e d i n that the predetermined value for the time of the stimulation phase (I) is chosen in the interval of 30-100 seconds when a cow is milked. 7. A method according to any one of the preceding claims, c h a r a c t er i z e d i n that the predetermined value of the milk quantity is chosen in the range of 0,2 - 2,0 kg when a cow is milked. 8. A method according to claim 7, c h a r a c t e ¬ r i z e d i n that the predetermined value of the milk quantity is chosen in the range of 0,4 - 0,8 kg. 9. A method according to any of the preceding claims, c h a r a c t e r i z e d i n that during the stimulation phase (I) the animal's teats are exposed to pulses having a frequency which is at least 2 Hz. 10. A method according to claim 9, c h a r a c t e ¬ r i z e d i n that said frequency is at least 3 Hz.

Inventors: HOERBERG ANN-LOUISE, OERNERFORS BENNY, HOERBERG, ANN-LOUISE, OERNERFORS, BENNY
Applicants: HOERBERG ANN LOUISE, OERNERFORS BENNY, TETRA LAVAL HOLDINGS & FINANCE, HOERBERG, ANN-LOUISE, OERNERFORS, BENNY, TETRA LAVAL HOLDINGS & FINANCE S.A.
Application year: 1995
Main classification: A01J5
IPC codes: A01J5