Method for operating a milking plant

Abstract

In order to avoid negative changes in the teat ends of a cow, in particular to avoid hyperkeratoses, the invention proposes a method for operating a milking system in which at least one of the parameters from total pressure per cycle, minimum total pressure per cycle or the ratio of total suction to total pressure is determined for at least one animal of a herd during at least one part of a milking process, and is compared with at least one reference value.

Claims

1. A method for operating a milking system, the method comprising the steps of: determining at least one parameter from the group consisting of: total pressure per cycle, wherein the total pressure per cycle is determined from an integral of a differential pressure curve and a fold-in pressure straight line over a predetermined time interval, wherein the differential pressure curve is determined from a vacuum in a short pulsation hose and a vacuum in a short milk hose; and minimum total pressure per cycle, wherein the minimum total pressure per cycle is determined by the lowest total pressure per cycle; and a ratio of total suction per cycle to total pressure per cycle for at least one animal of a herd during at least one part of a milking process, wherein the total pressure per cycle is defined as the integral of the pressure in the short milk hose in the predetermined time interval during a suction cycle; and comparing the parameter to at least one reference value.

2. The method of claim 1, in which the total pressure per cycle is determined using a value from the group consisting of: an arithmetic, geometric, and harmonic mean value.

3. The method of claim 1, in which the parameter is determined during an entire milking process.

4. The method of claim 1, in which the reference value for the parameter total pressure per cycle lies between 5 kPa's and 11 kPa's.

5. The method of claim 1, in which the reference value for the parameter minimum total pressure per cycle lies between 5 kPa's and 9 kPa's.

6. The method of claim 1, in which the reference value for the ratio of total suction to total pressure lies between 2 and 5.

7. The method of claim 1, and further comprising the step of: changing a fold-in pressure of at least one teat liner.

8. The method of claim 1, and further comprising the step of: changing at least one operating parameter of a pulsator.

9. The method of claim 1, and further comprising the step of: changing a level of vacuum in an area of a teat end in a milking cup.

10. The method of claim 1, and further comprising the step of: varying vacuum in an area of a teat end in a milking cup.

11. The method of claim 1, in which the reference value for the parameter total pressure per cycle lies between 6.75 kPa's and 9 kPa's.

12. The method of claim 1, in which the reference value for the parameter minimum total pressure per cycle lies between 5.30 kPa's and 8.10 kPa's.

13. The method of claim 1, in which the reference value for the ratio of total suction to total pressure lies between 2.75 and 3.75.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a graph of the pressure variations,

(2) FIG. 2 shows a graph with total pressure per cycle, and

(3) FIG. 3 shows a graph with total suction per cycle.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 shows a graph of the relevant pressure variations during a cycle which comprises a plurality of pulsation cycles. The variation of the vacuum in the short pulsation hose is shown dashed. The dash-dotted line reproduces the variation of the vacuum in the short milk hose over the time t. It can be seen from the variation of the vacuum in the short milk hose that the vacuum fluctuates between about 35 kPa and 40 kPa. At each point in time, the differential pressure between the vacuum in the short milk hose and the vacuum in the short pulsation hose is determined. This differential pressure is illustrated as a curve in FIG. 1. In the area in which the vacuum in the short pulsation hose is 0, the variation of the differential pressure corresponds to that of the vacuum in the short milk hose. The pressure variation in the short milk hose should be measured adjacent to the teat end. The variation of the differential pressure is illustrated in FIG. 1 as a continuous line.

(5) FIG. 1 also shows the fold-in pressure value of the teat liner, which is around 11 kPa in the example illustrated. The fold-in pressure is time-independent. It is constant. In the figure, it is shown as dash-dot-dot.

(6) The illustration according to FIG. 1 reveals that, at the times t.sub.1, t.sub.2, t.sub.3 and t.sub.4, the differential pressure curve and the fold-in pressure of the teat liner exhibit intersections.

(7) The fold-in pressure of the teat liner is the pressure difference which is necessary to deform the teat liner to such an extent that the opposite sides of the teat liner shaft just touch. According to this definition, the teat liner is open when the differential pressure is lower than the fold-in pressure of the teat liner. In the time interval between t.sub.2 and t.sub.3, the teat liner is open.

(8) In the time intervals t.sub.1 to t.sub.2 and t.sub.3 to t.sub.4, the teat liner is closed.

(9) FIG. 2 shows the graph according to FIG. 1 supplemented by the parameter total pressure per cycle, which is illustrated as a hatched area. The total pressure per cycle corresponds to the area illustrated hatched according to FIG. 2 and the by the variation of the differential pressure for the duration of the closed teat liner. The total pressure per cycle can be determined as a mean value during a milking process.

(10) From the thus determined total pressures per cycle, the lowest total pressure per cycle can also be derived.

(11) FIG. 3 shows a graph in which the pressure variations corresponding to the graph according to FIGS. 1 and 2 are illustrated. Hatched in FIG. 3 is an area which lies between the times t.sub.2 and t.sub.3 and is bounded by the zero value (zero value is the value at which the pressure is zero kPa) and the pressure in the short milk hose. This area forms the total suction per cycle and can be determined, for example, by forming an integral.

(12) From the parameters determined in this way, comprising total pressure per cycle, lowest total pressure per cycle and the ratio of total consumption to total pressure, parameters which can be compared with reference values are provided. If the parameters lie outside a tolerance band, it can be assumed that the milking system is not operating in an optimal state, which can be reflected, for example, in the formation of hyperkeratoses. The individual components or variations of the vacua can thus be controlled or adjusted such that the milking system preferably operates within a tolerance band around the reference values, which has a positive effect on the teat condition.

(13) The adaptation of the milking system can be carried out during the milking process. In particular, changes of operating vacuum of the milking system and also pulsator settings can be derived automatically and controlled or regulated automatically. However, this is not absolutely necessary. An adaptation of the operating parameters, in particular of the operating vacuum and of the pulsator settings of the milking system, can also be carried out in an animal-individual manner.

(14) Examinations have been carried out in about 30 herds, wherein the herds examined comprised Holstein, Red Holstein and Holstein-Frisian cows. There were weakly significant positive correlations with system vacuum (r=0.459) and with the maximum differential pressure in the massage phase (r=0.366). The strongest relationship with the frequency of horny hyperkeratoses in the herd was had by the parameters total pressure per cycle, lowest total pressure per cycle and the ratio of total suction to total pressure. All three parameters exhibited a quadratic relationship.

(15) TABLE-US-00001 Correlation coefficient r Preferred range Total pressure per cycle 0.760 6.75-9.00 kPa*s Lowest total pressure per cycle 0.746 5.30-8.10 kPa*s Total suction per total pressure 0.616 2.75-3.75

(16) For all three parameters, it is possible to detect both preferred ranges and also ranges with an excessively high or excessively low pressure action of the teat liner. In the case of an excessively high pressure action, the teat tissue reacts with intensified horny skin formation (callusing). In the case of an excessively low pressure action, the teat swells (edema), and the lasting action of the teat liner on this swollen teat causes numerous lesions, which leads to inflammation and ultimately to scar tissue. Furthermore, an examination of the change in the papillary duct condition in an operation having a herd-wide poor papillary duct condition (28% of the cows had a hyperkeratosis of class III and IV) was carried out. The classification of the hyperkeratosis was carried out in accordance with Methods for Evaluating Teat Condition Recommended by the Teat Club International. The herd examined comprised 60 lactating Holstein cows which had been milked in a 26 herringbone milking parlor with deep-routed milking line and automatic removal with a system vacuum of 42.7 kPa and a fold-in pressure of the teat lining of 7.7 kPa. The measurements of the pressure variations were carried out as a simultaneous 2-channel measurement with a measuring frequency of 30 Hz. Measurements were always carried out on a front quarter. The measurement began after the end of automatic stimulation and ended at the instant of automatic removal. The table below reproduces the measurements and the changes in the hyperkeratosis class.

(17) TABLE-US-00002 1.sup.st 2.sup.nd 3.sup.rd measurement: measurement: measurement: Day 0 Day 5 Day 49 System vacuum (kPa) 42.7 40.1 40.1 Fold-in pressure (kPa) 7.7 13.3 13.0 Total pressure per 10.63 7.52 6.85 cycle Total suction per cycle 21.56 22.27 20.67 Total pressure/Total 1.99 2.96 3.03 suction Hyperkeratosis class I 25% 27% 39% Hyperkeratosis class II 47% 40% 47% Hyperkeratosis 20% 25% 12% class III Hyperkeratosis 8% 8% 2% class IV

(18) In order to improve the milking conditions, a change was made to the teat liner (increase of the fold-in pressure from 7.7 kPa to 13.3 kPa). The increase in the fold-in pressure led to a lowering of the parameter total pressure per cycle. A harder teat liner closes later, opens earlier and, in the fully collapsed state, exerts less pressure on the teat.

(19) The system vacuum was lowered from 42.7 to 40.1 kPa in the same time period. This change likewise influenced the value of the total pressure per cycle. According to theoretical calculations, with the same level of vacuum, a total pressure per cycle of 8.36 kPa would have been expected. It is therefore possible to draw the conclusion that the reduction in the vacuum of the system by 2.6 kPa resulted in a reduction in the total pressure per cycle by 1 kPa*s (30% less). A shortening of the time of the relief phase (from 200 ms to 100 ms) increases the value of the total suction per cycle slightly. The results in the table show that the papillary duct condition of the animals in the herd had improved considerably within the trial time period. Only 14% of the animals still had a hyperkeratosis of classes III and IV.