Rotary MaxT

Steps to implementing MaxT

There are three steps to implementing MaxT: calculate, implement and monitor.

Step 1: Calculate

The first step is to determine your MaxT time. The easiest way to do this is to download DairyNZ’s Milksmart app. By entering the number of litres from the tanker docket, the number of cows going in the vat and your milking start times, the app will calculate the average milk volume per cow for each milking, and the appropriate MaxT time for this volume.

Alternatively, use these tables below to calculate your MaxT time manually.

Note: Farmers implementing MaxT for the first time have found it easier to start with using the morning MaxT time and monitoring at cups off as per Step 3.

Step 2: Implement

Before milking, for a range of platform speeds, time how long a bail takes from ‘cups on’ to ‘cups off’ (or before teat spray).

A shortcut to save time:

• Time the seconds a bail takes to pass.
• Multiply this by the number of bails from cups on to cups off
• Divide this by 60 to convert to minutes.

If you have Automatic Cup Removers (ACR)

Just about every ACR has the functionality of applying a maximum milking time except the Waikato Ultimate, although there is an upgrade available for this model. Some models of Delaval and GEA may require a service technician to change the maximum time setting. If this is the case, at the start of the season choose a time to handle peak milk and plan to change the MaxT time 2-3 times during the season. Contact your service technician if you have further questions.

Some ACR models can take the cups off at a set point in the rotation (point take-off), i.e. just before the teat sprayer and/or exit on the bridge. If you have this capability, setting the correct platform speed and maintaining it is extremely important.

At milking:

• Use the list on your console to set the desired MaxT time from cups on to cups off.
• Do not slow or stop the platform to fill empty bails.
• Always stand next to the bridge to ensure cows have the longest milking time possible between cups on and cups off.
• At cups off - depending on your rotary, your options to remove cups are:
  • The person at cups off removes all clusters on every cow and exits every cow after one rotation, or
  • Use the maximum milking time or the ‘point take-off’ function of your ACRs to remove clusters one bail before the teat sprayer as explained above.

Both methods still require the correct platform speed to be set and maintained. Milkings should also be monitored and/or checks put in place to ensure the platform is not operated at faster speeds than those required to ensure the correct platform MaxT times.

Note: if part of the herd is milked once a day, put these cows in one herd and allow them additional time.

Step 3: Monitor

The final step is regular monitoring. Once a week at an afternoon milking, monitor five groups of 10 cows. When monitoring, look at the cows at the cups off position (i.e. once the cluster has been on for the MaxT time).

• If most groups have fewer than two cows that are being shortened, you can reduce the MaxT time.
• If most groups have more than two cows that are being shortened, increase the MaxT time.
• If most groups have two cows in every 10 that are being shortened, you do not need to make any changes.

Alternative calculations

Using a MaxT specific for AM and PM milking can sometimes be impractical, for example when uneven milking intervals result in a target MaxT time as low as 5 minutes, or when ACRs settings have to be manually changed between milkings.

One solution is to use the morning MaxT time for both milkings, but this will result in reduced efficiency in the afternoons. Another is to make the milking intervals more even but that may mean milking at undesirable times of the day.

FixedT

Another alternative option is FixedT – a MaxT based on the average yield per milking (see table below) applied at all milkings, ignoring differences in milking intervals. This shifts more milk from the longer milking to the shorter milking making both milkings more efficient while still allowing the milkings to occur at favourable times of the day.

A study at DairyNZ’s Lye farm tested FixedT for four milking intervals (TAD 8-16 h, TAD 10-14 h, 3-in-2 10-19-19 and OAD) at peak and mid-lactation, using a 70:30 pulsation ratio, and found no effect on udder health or milk production, when less than 33% of the herd had their milking shortened. For the 8-16 and 10-19-19 intervals, where one milking interval was 3-4 hours shorter than the others, the fat yield was reduced when more than 36% of cows were shortened.

Find your FixedT time from the table below based on daily milk yield and milking frequency