A METHOD OF MILKING AN ANIMAL

Abstract: In a method of milking an animal, the conditions of the milking operation are substantially stable during a main milking phase and are unintentionally changed during a terminating milking phase. According to the invention, at least one unintentional change in the milking operation conditions during at least one initial milking operation is sensed, at least one milking parameter is registered in response to said sensed unintentional change, and each said registered parameter is utilized to change the milking conditions of one or more following milking operations for the same animal before each said sensed unintentional change is expected to occur.

Description: A Method of Milking an Animal The present invention relates to a method of milking an animal by means of a milking machine, the conditions of the milking operation being substantially stable during a main milking phase, when the milk flow is substantially constant, and being unintentionally changed during a terminating milking phase, during which the milk flow starts decreasing. The milking machine usually comprises a cluster of teat cups, each teat cup containing a liner forming a pulsation chamber therebetween. During milking the pulsation chamber is subjected to a pulsating pressure varying between a low pressure and a high pressure, while the interior of the liner is subjected to a constant sub-pressure being substantially equal to said low pressure in the pulsation chamber. When the milking conditions are stable during the main milking phase, the teats are kept in the liners in intended positions and the milk is yielded from the udder in a substantially constant flow of milk. During the terminating milking phase, the position of each liner rela- tive to its teat changes unintentionally from the intended position in spite of the fact that the operation of the milking machine is un¬ changed. This change in position throttles the milk flow passages in the teats, so that the milk flow finally ceases resulting in an unde¬ sirable rest amount of milk in the udder. The cause of said change in position of each liner relative to its teat will be explained below. When the main part of the milk in the udder has been extracted during milking, the pressure in the udder drops resulting in a decrease of the milk flow from the udder. Under the influence from said constant sub-pressure prevailing in the liner below the tip of each teat and because of said decreasing milk flow, each teat will be slacker and slacker and its friction engagement with the liner will be weaker and weaker. Finally each teat slides deeper into its liner, so that the lips surrounding the upper opening of the latter throttles the milk flow passage between the interior of the udder and the interior of the teat. After a while, the milk flow through each teat is completely stopped by the throttling action of its liner, so that a rest amount of milk is left in the udder. The rest milk cannot be extracted by means of the milking machine without a time-consuming manual manipulation of the teat cups, i.e. the teat cups need to be pulled downwardly. However, before the teat cups can be manually manipulated to gain the rest milk, usually some time will pass during which the animal will be dry-milked, i.e. there is no or an insignificant flow of milk in the teats. Such a dry- milking treats the teats ungently and might irritate the animal. To avoid dry-milking, some known types of milking machines automa¬ tically removes the teat cups from the teats as soon as the milk flow has ceased. Thus, the rest milk is not extracted. This means the advantage, besides the advantage of avoiding dry-milking, that no time-consuming manual manipulation of the teat cups is necessary. A drawback is that the lactation production of milk might be reduced, the amount of this reduction being dependent on the amount of the rest milk. Another drawback is that leaving the rest milk could increase the risk of arising infections in the udder. Thus, to minimize this risk it may very well be the fact that as much as possible of the rest milk should always be extracted. There are attempts made to control a milking machine in order to counteract said unintentional change in the conditions of the milking operation, so that the rest milk is eliminated or at least substan- tially reduced. According to one such an attempt, during the termi¬ nating milking phase, the sub-pressure in the liner is reduced in response to a sensed decrease of the milk flow from the main milk flow to a predetermined part of the latter. By this measure, each liner should remain in a sufficient friction engagement with its teat, since said reduced sub-pressure causes a corresponding reduction of the sub-pressure prevailing in the teat, so that the teat will not be slacked. However, in practice it has been proved that the reduction of the rest milk in most milking occasions is rather insignificant. The benefit is that, because of the reduced sub-pressure, the teats are treated more gently when dry-milking occurs. The reason for the failure of the above described attempt is that the liner often very rapidly slides upwards on the teat as soon as the milk flow starts decreasing from the main milk flow. Once the liner has slided up to an upper position on the teat, it remains in that position no matter if the milking machine is controlled, such that the various pressures in the teat cup are changed and/or the pulsation characteristics are changed. Thus, it will often be too late to change the sub-pressure in each liner in response to said change in the milk flow, because of each liner having already slided more or less upwards on the teat. The object of the present invention is to provide a new method of milking, which results in an elimination of or at least a significant reduction of the rest milk in the udder of the animal. This object is obtained by a method of the kind initially stated, which mainly is characterized by sensing at least one unintentional change in the milking operation conditions during at least one initial milking operation, registering at least one milking operation para¬ meter in response to said sensed unintentional change in the milking operation conditions, and utilizing each said registered parameter to change the milking conditions of one or more following milking opera¬ tions for the same animal before each said sensed unintentional change in the milking conditions is expected to occur. Hereby, the advantage is gained that the milking conditions can be changed in a controlled manner and in time, so that any unwanted unintentional change in the milking conditions (a change of the position of each liner relative to its teat) is avoided or at least counteracted. During said initial milking operation, preferably an unintentional decrease of the milk flow is sensed. Alternatively or in combination, an unintentional decrease of the pressure in each liner above the tip of its teat and/or an unintentional change in the position of each liner relative to its teat could be sensed. The milking operation parameter to be registered preferably is the milk flow, but it could also be the retardation of the milk flow, the time of the milk flow or the amount of milk milked from the animal. Of course, it would be possible to use a combination of the above-mentioned registered parameters. The milking conditions are preferably changed during said one or more following milking operations by decreasing a sub-pressure acting on the teats, possibly in combination with one or more of the following alternatives: In a machine comprising at least one teat cup with a liner forming a pulsation chamber therebetween, said pulsation chamber being subjected to a pulsating pressure varying between a low pressure and a high pressure, the milking conditions are changed by: 1. Increasing the frequency of the pulsation pressure. This results in that each liner will not have sufficient time to open completely during each pulsation cycle, whereby the friction engagement between each liner and its teat will be maintained. 2. Decreasing the pulsating ratio of the low pressure to the high pressure. This will also result in that each liner will not have sufficient time to open completely during each pulsation cycle. 3. Increasing the low pressure in the pulsation chamber. This will result in a reduction of the opening capability of each liner. A. Reducing the velocity of movement of each liner when opening or closing the liner. This will also result in that each liner will not have sufficient time to open completely during each pulsation cycle. 5. Constantly subjecting said pulsation chamber to said high pres¬ sure. This will result in that each liner will be in a constant friction engagement with its teat. Of course, it would be possible to use a combination of the above- mentioned measures 1-5 to change the milking conditions. The invention is described in the following by way of an example. A cow is milked in an initial milking operation by means of a milking machine, which is operated in a constant manner. The milk flow is sensed and the value of this is registered when the milk flow has decreased from the main flow to a predetermined part of the latter. In the same way, several such registered values of the milk flow is collected from subsequent initial milking operations and a mean value of the milk flow with standard deviation is calculated from the col¬ lected values of milk flow. Then, said calculated mean value of the milk flow is utilized for controlling each of the following milking operations, such that in response to the sensed value of the milk flow in each following operation the sub-pressure below the teats in the liners is decreased before the milk flow has decreased to said mean value of the milk flow added with the standard deviation of the latter. Alternatively, only one registered value of the milk flow obtained from one initial milking operation could be utilized for controlling the following milking operations, on condition that the sub-pressure is decreased well before the milk flow has decreased to this last mentioned value.

Claims: Clai s 1. A method of milking an animal by means of a milking machine, the conditions of the milking operation being substantially stable during a main milking phase, when the milk flow is substantially constant, and being unintentionally changed during a terminating milking phase, during which the milk flow starts decreasing, c h a r a c t e ¬ r i z e d b y sensing at least one unintentional change in the milking operation conditions during at least one initial milking operation, registering at least one milking operation parameter in response to said sensed unintentional change in the milking operation conditions, and utilizing each said registered parameter to change the milking conditions of one or more following milking operations for the same animal before each said sensed unintentional change in the milking conditions is expected to occur. 2. A method of milking according to claim 1, c h a r a c t e ¬ r i z e d i n that during each said initial milking operation an unintentional decrease of the milk flow is sensed. 3. A method according to claim 1 or 2, wherein the milking machine comprises at least one teat cup with a liner, c h a r a c t e ¬ r i z e i n that during each said initial milking operation an unintentional decrease of the pressure in each liner above the tip of its teat is sensed. 4. A method according to any of claims 1-3, wherein the milking machine comprises at least one teat cup with a liner, c h a r a c ¬ t e r i z e d i n that during each said initial milking operation an unintentional change in the position of each liner relative to its teat is sensed. 5. A method according to any of claims 1-4, c h a r a c t e ¬ r i z e d i n that one milking operation parameter, which is registered, is the milk flow. 6. A method according to any of claims 1-5, c h a r a c t e r i ¬ z e d in that one milking parameter, which is registered, is the retardation of the milk flow. 7. A method according to any of claims 1-6, c h a r a c t e ¬ r i z e d i n that one milking operation parameter, which is registered, is the time of the milk flow. 8. A method according to any of claims 1-7, c h a r a c t e - r i z e d i n that one milking operation parameter, which is registered, is the amount of milk milked from the animal. 9. A method according to any of claims 1-8, wherein the teats of the animal is subjected to a sub-pressure, c h a r a c t e - r i z e d i n that the milking conditions are changed during said one or more following milking operations by decreasing said sub- pressure. 10. A method according to any of claims 1-9, wherein the milking machine comprises at least one teat cup with a liner forming a pulsation chamber therebetween, said pulsation chamber being subjected to a pulsating pressure, c h a r a c t e r i z e d i n that the milking conditions are changed during said one or more following milking operations by increasing the frequency of the pulsating pressure. 11. A method according to any of claims 1-10, wherein the milking machine comprises at least one teat cup with a liner forming a pulsation chamber therebetween, said pulsation chamber being subjected to a pulsating pressure varying between a low pressure and a high pressure, c h a r a c t e r i z e d i n that the milking conditions are changed during said one or more following milking operations by decreasing the pulsating ratio of the low pressure to the high pressure. 12. A method according to any of claims 1-11, wherein the milking machine comprises at least one teat cup with a liner forming a pulsation chamber therebetween, said pulsation chamber being subjected to a pulsating pressure varying between a low pressure and a high pressure, c h a r a c t e r i z e d i n that the milking conditions are changed during said one or more following milking operations by increasing the low pressure in the pulsation chamber. 13. A method according to any of claims 1-12, wherein the milking machine comprises at least one teat cup with a liner forming a pulsation chamber therebetween, said pulsation chamber being subjected to a pulsating pressure causing the liner to alternately open and close the inner passage of the liner, c h a r a c t e r i z e d i n that the milking conditions are changed during said one or more following milking operations by reducing the velocity of movement of the liner when opening or closing the liner. 14. A method according to any of claims 1-13, wherein the milking machine comprises at least one teat cup with a liner forming a pulsation chamber therebetween, said pulsation chamber being subjected to a pulsating pressure varying between a low pressure and a high pressure, c h a r a c t e r i z e d i n that the milking con¬ ditions are changed during said one or more following milking operations by constantly subjecting said pulsation chamber to said high pressure.

Inventors: GRIMM HARTMUT, RABOLD K, GRIMM, HARTMUT, RABOLD, K.
Applicants: ALFA LAVAL AGRI INT, ALFA-LAVAL AGRICULTURE INTERNATIONAL AB
Application year: 1989
Main classification: A01J7
IPC codes: A01J5