There are several opportunities to refine milking machine settings or implement management strategies. The milking duration of the cow can be reduced by either option below:

1. Optimise the milking machine to harvest milk more quickly by:

• Increasing pulsation ratio

  Increasing the pulsation ratio. Most dairies have been set to a 60:40 pulsation ratio. Increasing this ratio to 65:35, 67:33 or 70:30 has the effect of increasing the amount of time per pulsation cycle the machine is harvesting milk, reducing milking duration.  

  A key requirement of all pulsation systems is to have a resting phase (d-phase) of at least 150ms. Field experience has led to the recommendation that the d-phase should be 20% of each cycle to allow for some decline in pulsator performance until the next scheduled maintenance.  This is especially important if you are operating pulsation ratios of 70:30. See the pulsation ratio page for more information.  

  Increasing pulsation ratio is best used in combination with the other strategies listed, particularly MaxT where by increasing pulsation ratio will decrease the number of cows that are shortened for a given time. Other situations include where ACRs are installed or the herd is milked OAD as there is 24hours of milk to harvest at a single milking.  

• Selecting fast milking liners

  At your next liner change take the opportunity to review the liners that fit your milking system to identify the optimal liners for your herd.   

  When cupping between the two back legs you have the opportunity to use a different liner for front and back quarters. Typically, rear quarters produce more milk that front quarters, and accordingly are normally the last to finish milking. Liners that are good for minimising cup slip are often slower at harvesting milk and vice versa.

  The use of liners that are good for minimising cup slip on front quarters (where time is not as important and slip often occurs), and faster milking liners on back quarters can reduce milking duration. See the liner selection page for more information.

  This strategy is best used in combination with the other strategies explained on this page.

2. End milking early by either or both:

• Implementing a maximum time (MaxT) milking strategy

  Apply a maximum milking time (MaxT) to shorten up to the slowest 20% of the herd. This can be applied in both herringbones and rotaries with and without ACRs. It results in some milk being left behind in the udder of the slowest 20% of the herd but research has concluded this can be done without compromising milk production or udder health. MaxT is the most effective strategy for improving milking efficiency.

• Increasing the low flow setting of ACRs

  If you have ACRs, increase the low flow setting that triggers cluster removal. This approach is somewhat similar to applying a maximum milking time and can be done in conjunction with MaxT. Increasing this setting will remove the cups earlier leaving increased residual milk in the udder, which can be harvested more efficiently at the next milking.

  Increasing your ACR low flow setting from 0.2 kg/min to 0.4 kg/min (or equivalent) is normally the first step recommended, however low flow settings of up to 0.8 kg/min have been tested in NZ. If your ACR has the option of applying a maximum milking time then using MaxT is more effective at improving milking efficiency than increasing the low flow setting.

  Some ACR’s use a conductivity sensor rather than an actual flow sensor for detecting the low flow rate. With these ACR’s talk to your service agent on how to set to approximately 0.4 kg/min. Alternatively make a change and evaluate the cows at cups off. 

Why applying a maximum milking time is so effective

Within a herd there is considerable variation in the amount of time a cow takes to milk. This duration is correlated with milk yield, but there are other contributing factors, such as cows that take longer to milk are not necessarily the highest producers.

This variation presents a challenge for optimising milking efficiency; in a swingover herringbone the entire row is held up by the slowest cow(s). Cupping slow milking cows early does not help significantly unless by chance the cow on the other side of the pit, before or after, has a shorter milking duration.

In a rotary, a slow milking cow only occupies a bail rather than the slowing the whole row but this bail could be utilised for a new cow. Note that reducing go-around cows by slowing the rotary platform does not reduce herd milking duration, see the milking routine page for more explanation.

MaxT for your farm dairy

Leave milk in the udder without compromising production or udder health

Leaving residual milk in the udder goes against a long-held industry belief that it will cause lost production and mastitis. In short, the residual milk is retained to the next milking where it can be harvested faster.

Milk is held in two compartments of the udder; the cistern (a bag above the teat) which holds roughly 20% and the alveoli (the cells where the milk is made) which holds the other 80%. When clusters are attached, the milk harvested in the first few minutes is from the cistern, then the milk ejection or let down reflex is triggered. This causes the remaining milk to move from the alveoli into the cistern where it can be harvested by the machine.

Research has shown that the milk flow curve changes after cows have had their milking shortened. At the next milking there is an increase milk flow rate early in the milking and also at peak milk flow, likely due to there being more milk in the cistern. This increases the average milk flow rate allowing the same amount of milk to be harvested in a shorter duration.

This concept is explained in the animation below: