Cluster attachment and removal

Cluster attachment

Attaching clusters is a major part of the milking routine. Having a consistent routine across all milkers is important. Clusters which are not attached correctly can lead to teat end damage, cup slipping, and mastitis.

The benefits of correct cup attachment include:

• Increased milking efficiency.
• Reduced milker fatigue and injury.
• Improved cow behaviour - cows will be calmer and more acceptant of the clusters.

Attachment of clusters is given surprisingly little attention considering it has a major role in the milking routine.

Most milkers develop their own method without any direction. This can lead to poor cupping techniques and issues with repetitive strain injury. The aim is to find ways to change clusters consistently and reliably without unnecessary physical strain and avoid the problems of muscle/tendon overuse.

Cupping techniques

Two cupping techniques are explained here and switching between methods during milking is recommended to relieve muscle strain. Each method works on rotaries or herringbones, although there are some refinements depending on the dairy type.

Round-the-circle method

This method is (or should be) taught to all new milkers as a simple, easy-to-learn, reasonably quick method that avoids problems. It is not the fastest method but it is reliable and easier on the milker because there is much less chance of getting kicked.

Round-the-circle for herringbones

Use the right hand to put the cups on the right hand side row of cows (facing the exit) because it is easier to reach through the back legs.

• Pick up the claw with the left hand and reach over the left arm to put on the left back cup (using right hand) at the same time,
• then left front,
• then right front,
• then right back.

On the left hand side of the platform, use the left hand to put on the cups.

This creates a change in muscle usage depending on whether the clusters are being placed on the right or left side of the herringbone.

Round-the-circle for rotaries

The Round-the-Circle method depends on which way the platform is rotating. For clockwise rotation:

• Pick up the claw with the right hand, reach over the right arm with the left hand and put on the right back cup - the first seen as the cow approaches,
• then right front,
• then left front,
• then left back - as the cow goes past.

If the rotation is anti-clockwise reverse this process.

Two-at-a-time method

For a rest try putting on the two front cups more or less at once, then the back right, then the back left with the other hand.

Cluster Removal

All milkers should know how to remove clusters correctly - clusters which are left on too long result in over-milking, liner creep and teat end damage.

Milking machine function must be maintained to ensure cluster removal is easy for the milker, and causes no cow discomfort or teat damage.

The benefits of correct cup removal include:

• Cows are milked out but not over-milked with correct timing of removal.
• Milk quality maintained.
• Increased milking efficiency.
• Reduced animal health issues through ensuring teat damage does not occur.

Automatic cluster removal

Automatic cluster removers (ACR) can boost productivity per milker in both rotary and herringbone dairies. Working conditions are also improved by reducing cluster handling requirements.

A large percentage of New Zealand’s dairy cows are regularly over-milked resulting in reduced milking speed, poor udder health, and cow discomfort. ACR are designed to remove a cluster from individual cows at a pre-determined end point of milking and can provide a solution to these issues.

Manual cluster removal

It is important to take care when removing clusters to avoid rapid inrushes of air that have been shown to increase the risk of mastitis infection.

The first step is to break the vacuum.

• Kink the long milk tube or pull the vacuum cut-off valve and wait 1-2 seconds while the claw fills with air at atmospheric pressure.
• Rotate the cluster 30 - 60° to break the seal and assist with cluster removal. When the clusters are not sliding off freely, check the vacuum to the clusters is being fully cut off and the setup of the milking machine including the compatibility of the liners with the cows and the working vacuum level.
• For large volume clusters (400 ml plus) it is necessary to kink both the long milk tube and pull the vacuum cut-off valve to reduce vacuum in a timely manner.
• Once the cluster is removed the milker should be able to hang it up on a convenient hook or swing it over to another cow.

Trouble-shooting:

• Difficult cluster removal:
  • Clusters that are hard to remove, or are not releasing correctly, are a sign that the equipment is not working properly. Check the machinery if this is happening.
  • Check air admission holes and repair faulty vacuum shut-off valves as soon as possible.
• Incomplete milking:
  • Incomplete milking is defined as having more than 20% of quarters with greater than 250 ml of milk that can be stripped out by hand after milking.

How to avoid over milking

As over-milking is a more common problem than incomplete milking it is better to remove the cluster too early rather than too late.

• Clusters should be removed when there is less than 100 ml of milk in any quarter – there should be a dribble of milk flow in the sight bowl.

In New Zealand herds, over-milking can be excessive in the range of 2-5 min per cow for many herds, in both herringbone and rotary dairies. It is particularly common  in late lactation or dairies that have too many clusters for the number of people milking.

• Over-milking is when cups remain attached to teats after a cow’s milk flow rate has fallen below a certain end-point (traditionally 200ml/min).

Extensive international research indicates that cows giving 10L per milking (not per day) can be milked in 5 min, while cows giving 15L per milking can be milked in about 6 min. This may be about a minute longer in New Zealand where cows commonly have less preparation e.g. teat washing, before milking.

Even so, considering typical rotation times are 12 minutes for many rotary platforms (with some cows going around twice), many cows are being severely over-milked. This can be caused by clusters being attached too early or left on too late.

• If clusters are removed manually, milkers need to have enough time to reach all cows before significant over-milking occurs (minimal if the mean overmilking time is less than 1 minute per cow; moderate if between 1 and 2 minutes per cow). Signs of continuous over-milking may indicate that the milker is handling too many clusters.
• Take care with newly calved cows, young cows with small teats, and cows on test buckets as they are especially susceptible to injury through over-milking.
• Watch for cows kicking at the clusters and teat end damage as these can indicate that cows are being over-milked.
• Avoid using weights or machine stripping slow milking cows - it leads to over-milking of the other cows.