Forces on teats in Voluntary Milking Systems


Sandra. Rose1), J. Erickson2), C. Børsting2), R. Brunsch1), E. Scherping1), J. Klimetschek3)


1) Institute of Agricultural Engineering e.V. (ATB), Max-Eyth-Allee 100, 14469 Potsdam,

   Germany, phone: +49 (0)331/5699-510, email:          


2) Danish Cattle Research Centre,  Burrehøjvej 49, 8830 Tjele,

   Denmark, phone: +45 87991500, email:          


3) German Agricultural Society (DLG), Test station for Agricultural Machine, Lerchensteig

42, 14469 Potsdam Germany, phone: +49 (0)331/56702-0, email: w.huschke@dlg-




A lot of dairy farms have big problems with udder health. One important reason can be milking machines placed in a wrong position. Because of un-correct placed support arms and milk tubes you get pulling of teats by different forces. For this reason, the DLG has developed test machinery, which offers the possibility to measure four forces (vertical-, turn-, side- and tilt force) (Fig. 1). Furthermore, you can analyse different udder forms and positions with the test machinery.


Figure 1: The test machine in a VMS


Different scientists assert, that Automatic Milking Systems (AMS) are better for udder health than conventional systems. For example Ipema and de Koning (1997), Worstorff and Hamann (1998) and Hogeveen et al. (2000) expected a higher average milk yield per cow presumably explained by a higher number of milkings per day. But, there will be some more aspects, which influence the udder health status. Maybe AMS’s are more regular in putting the teat cups on and the forces are distributed more regularly to all teats than in conventional milking parlours.. Presumably, the differences between two AMS units from same company are not as large as from milking place to milking place in a milking parlour. Another aspect is the adaptability of the teat cups to different udder forms. To examine this the ATB and DLG performed an experiment at the Danish Cattle Research Centre (KFC).

For an investigation on the influence of the resulting forces caused by different udder forms and to find out the differences from system to system, tree different udder forms (normal, stuffy, wide standing) was tested in three Voluntary Milking Systems (VMSTM) units at KFC. In this system from DeLaval the 4 cups are directly connected to their individual tube without being gathered in a cluster.

The teat cups were put on five times per udder form in each VMS.  Data were send to a PC and immediately after the system was checked for problems and difficulties.



Detection of problems

One problem which was detected immediately, was that there was one tube at the right rear teat at VMS1 with a technical defect, because the tube was not going out long enough and therefore the teat was forked for the whole milking process. If this is the case every day it can cause udder disease (Fig. 2).



Figure 2: Forked teat cup at rear teat







As you can see in Diagram 1 the side force of the right rear teat was more than 3 times higher than for the other forces. The same case you can notice in Diagram 2 with the tilt force on the right rear teat.

These are the consequences of the technical problem shown in Figure 2. As a first result it seems that the test machine is helpful for checking this type of milking machines. As a second result, it was shown that robots could have problems with irregular attachment of cups and problems with right positioning of the cups like in conventional milking systems.


Adaptability of milking cluster by different udder forms

Many milking clusters have difficulties in adapting the cluster at different udder forms especially to stuffy udders.



Diagram 3 shows the average vertical force in conventional milking parlours and the average of the three VMS units at KFC. In the VMS units the force was nearly the same on every teat and in every system. There were only differences from maximum to minimum of 0,5Newton. That means the adaptability of the forces was good. The graph of the conventional milking parlour (Diagram 3) shows in comparison with VMS clearly higher differences between the front and rear teats. The maximum was 13,5 N and the minimum at –1,7 N. That means that the front teats are loaded with eight times higher force than the rear teats.



In regard to forces to the teats the VMS is in general a good working system. Sometimes we had problems putting on the teat cups on. But when the teat cups had been put on successfully the system worked reliable.

The differences between the three VMS units were not significant. The adaptability of the ‘milking cluster’/teat cups in the VMS could be valuated very positive. All teats were loaded with nearly the same force, which resulted only from the weight of the teat cups and tubes. So the forces on the teats could be minimized.  This could be a reason for better udder health compared to conventional milking systems. 

But also we had seen in Diagram 1 and 2, that there is the possibility of problems with un-correct positioning of the teat cups. In conventional milking systems, mainly milker and teat cup liners influence this. In AMS it is mainly influenced by reliable working technique.

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