During a recent farm visit, routine milking time testing of the milking machines in this dairy quickly showed that the system vacuum was at 39 kPa – very low for a highline swingover herringbone!

We immediately went looking for the dairy’s vacuum gauge, and after a brief Sherlock Holmes detective effort, we finally found the gauge way up high in the middle of a mass of pipework, facing towards one side of the herringbone.

In this position it was impossible for a person in the pit to read the gauge, and even standing on one platform of the herringbone, regular prior yoga sessions would have been needed to twist our bodies enough to easily read the gauge.

Once found, we could see that the gauge was reading 46 kPa, a significant difference to what was actually happening in the milking system.

A change in milking system vacuum level of this magnitude can result in changes to milking performance that you might readily notice - extra cup slip, difficulty attaching cups at cups on, clusters that do not drop off as easily at cup removal, unsettled cows, swollen or discoloured teats after cup removal, etc.

However, even smaller changes in vacuum level can have an effect, often long before the change reaches the stage where you see these more obvious signs.

We regularly see farms where an unnoticed change of only 1 - 2 kPa in the system vacuum level has had a significant impact on teat condition, greatly increasing the risk of mastitis, but without causing any of the above signs!

These relatively small changes in vacuum are often difficult to notice from one milking to the next and can be very hard to define by eye on the dial of a typical analogue gauge - and if you are in the dairy shed every day, it is even more difficult to notice a small change!

Recently, at a couple of programmed farm visits we discovered that vacuum levels which had previously been set at the ideal level for the farm had unknowingly changed from this ideal level. On most of these farms, that effect was immediately evident in our teat scoring, and on a couple of the farms, mastitis levels and cell counts had also started to increase.

What are the key lessons and how can we avoid these risks?

  • Vacuum regulators and vacuum gauges are not “set and forget”. Like all mechanical systems, they need to be checked and serviced regularly.
  • AMMTA milking machine standards specify that the vacuum gauge should be in a position where it is easily read.
  • Analogue dial gauges can be difficult to read, and are more prone to “sticking” – if you have to tap the gauge to read it, the gauge needs replacing!
  • Digital gauges usually have large, easily read numerals.
  • It should be part of every milking routine, to check the vacuum gauge after the plant has started to ensure nothing has changed from the previously set level. If the vacuum has changed, a technician should be called to investigate why and reset the vacuum to the correct level.
  • Whilst it is possible to install monitoring equipment that will alert the operator to changes in vacuum, these systems are relatively expensive.

An effective option for most farms is to install a digital vacuum gauge in a highly visible position and then to ensure that it becomes part of the milking routine to check the gauge at every milking, commonly immediately after start up.

Digital Vacuum GaugeThis is an example of an installation clearly showing the vacuum level, and also that the vacuum in this dairy has started to "creep" away from the ideal level which has been recorded on the wall below the gauge.

These installations are simple, relatively inexpensive and can help to prevent a change in your vacuum causing you costly increases in mastitis risk - talk to your milking machine technician about the best option for your plant.

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