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The Lely Astronaut continuously monitors the milk flow per quarter during the milking, and take-off is done per individual quarter. This prevents overmilking when one quarter is finished earlier than another quarter. The exact take-off moment is determined by the take-off settings. Below is an explanation about the different take-off settings and how to interpret those.
How does it work?
With the Astronaut, we have the ability to milk at quarter level. The start of milking and milk flow rate are different per teat. Therefore, the take-off also happens independent of one another, which is monitored through a milk flow sensor in the MQC-II. The take-off moment is initiated when milk flow is below the take-off level for a certain number of seconds. The teat cup is than taken off by closing sleeve valves and a delay to relieve the vacuum from the cup.
How is take-off moment determined?
After 50% of the expected milk time, end of milk flow detection is activated. From that moment onwards, the teat cup can be taken-off based on end of milk flow, if the milk flow meets the take-off criterium. The take-off criterium is based on a take-off threshold and a number of seconds delay that the milk flow has to stay below the take-off threshold. The take-off threshold and the number of seconds delay are different per take-off method.
Figure 1: take-off definitions
In Horizon, four pre-set take-off methods can be chosen and one customizable take-off method (Custom Take-Off, abbreviated by CTO). For the pre-set take-off methods, the take-off level is calculated as fraction of the average milk flow. For CTO, this is based on a percentage of the average milk flow. More information on CTO is explained further in this article. Since the take-off level depends on average milk flow, different quarters have a different take-off threshold. This means that the teat cups for fast milking quarters are removed at a higher milk flow level than slower milking quarters. When milk flow is under the take of level, a delay time starts to count until 0. When the milk flow has not exceeded the take-off level during this delay time, the teat cup is taken off. If milk flow exceeds the take-off level, the delay time resets and starts to count until 0 as soon as milk flow drops below the take-off threshold. For each take-off setting, boundaries are set to prevent that the take-off threshold can go too low or too high.
Each take-off setting has different thresholds. See the table below for the different thresholds.
Quick take-off is the recommended take-off settings and provides a complete milk out without overmilking of the cows.
Normal take-off takes the teat cups off at a lower milk compared to Quick take-off. Hereby, take-off is slightly delayed especially for cows with lower milk speed or gradually declining milk flow towards the end of milking.
Extended take-off uses an additional 9 second take-off delay. This settings is not recommended on herd level since a significant delay is added after the milk flow drops below the take-off threshold
Custom Take Off (CTO)
Next to the pre-set take-off methods, a customizable take-off method is available: CTO. CTO is a setting to optimize the take-off moment, but this does require follow up from FMS. Before starting to work with this setting, focus on how to get a complete milking first. A complete milking means that congestion of the teat, especially towards the end of the milking is prevented. Congestion limits milk flow from the udder, and this cannot be solved by a quicker take-off setting.
CTO vs. pre-set Take-off settings
Custom Take Off and the pre-set take-off settings use a different algorithm. The exact numbers and seconds are therefore different between the pre-set take-off settings and CTO. The Horizon table shows how different options for Custom Take Off settings "translate" to the pre-set take-off settings, this can be used to provide a starting point to optimize milking settings if changing from Quick Take-Off to a slightly "quicker" take-off with CTO.
An example:
If currently Quick Take-Off is used, the "classic" algorithm is used to define take-off level and moment. This algorithm uses Milk flow / 3 to define take off level, and 6 seconds for delay.
When switching to CTO, a different algorithm is used. To have the same take-off performance, the CTO settings that compare best to the pre-set Quick Take-Off are 45% and 8 seconds.
When switching to CTO settings from Quick Take-off, a comparable take-off setting could be used as Quick Take-off with a minor adjustments at a time. Adjustments could be e.g. to switch from 45% to 50%, or decrease from 8 to 6 seconds delay.
Figure 2: CTO as shown in Horizon
Should I change take-off settings?
Depending on the farm situation, take-off settings might need to be evaluated. The best way to evaluate this is by checking teat signals and a by doing dynamic test. A dynamic test provides insight into vacuum levels and pulsation during the milking process. From the moment that milk flow starts to decline and mouthpiece chamber vacuum starts to increase, the teat-cup should be detached within 15 seconds. If this takes more than 15 seconds for a larger part of the herd, investigate whether this is caused by a slow take-off settings (e.g. Extended take-off) or by congestion of the teat.
Figure 3: Perfect dynamic test outcome. Stable and high milk flow rate as indicated by the teat end vacuum (green line) and minimal rise in mouthpiece chamber vacuum (red line) and for a short duration towards the end of milking when milk flow has ceased. Between teat cup take-off and the stop of milk flow less than 15 seconds is shown.
Should I delay take-off settings to achieve a complete milking?
A good start is half job done. This certainly applies to achieving a complete milking. Having a good start of the milking and stable milk flow during the milking prevents congestion and contributes to complete milking. When the milk flow is released in a “square” shaped milk flow profile, the influence of take-off settings becomes less. On the other hand, the influence of take-off settings on take-off moment for congested teats with a slow end is bigger (see figure 4). Delaying the teat cup take-off moment does not solve the reason for incomplete milking, being either too early take-offs by airflow or congestion of the teat. In case of congestion, extending the take-off moment can result in overmilking and thus resulting in more congestion and potentially teat end damage in de long term. Therefore, solving the reason for congestion will improve milking performance for these cows. Try to solve the reason for congestion and slow ending milkings. This can be done by adjusting milk access and pretreatment times to prevent bimodality. Or change liners, vacuum or pulsation to prevent congestion.
Right milk interval
Reduce milkings with short intervals (below 6 hours) and/or low milk yield (below 8 kg per milking). Milkings below 6 hours show a higher risk on bimodality and milkings with low milk yield have a higher risk on teat congestion. These insights can be seen in the FarmScan or in Horizon at e.g. Report 41 or the scatter graph of Milking - No. Of Milkings/Cow/Day.
2. Sufficient pre-treatment
Insufficient pre-treatment causes bimodality or a delayed start (Increased DMT or slow milk release) to the milking process. A pre-treatment time of around at least 60 seconds is recommended.
3. Right liners
The right liners provide sufficient massage and prevent congestion of the teat. A teat size measurement can indicate if the right liner size is used, while checking teat signals after milking can show if congestion occurs. A dynamic test can provide more insights into liner fit and show if liners and milk settings match the need the of the cow.
Figure 4: Effect of two different take-off settings on take-off moment for a complete milking (L) and milking with a slow end (R). The effect of the take-off level has a smaller effect on actual take-off moment for the square shaped milking compared to the slow ending milking.
Should I apply shorter take-off settings to increase milk speed?
As mentioned in the previous paragraphs, the influence of take-off setting on actual take-off moment is less for square shaped milkings compared to slow ending milkings. Slow ending milkings directly influence milk speed. Slow ending milkings can be the result of milking with lower milk yield.
An effective way to increase milk speed is by reducing milkings with lower milk yield. Review milk access to prevent too frequent milkings or milking opportunities that allow milkings with low milk yield.
A next step to prevent slower milkings is by increasing pre-treatment time to have a well filled teat from the beginning of the milking onwards. 2x4 or 2x5 for A5 can help to decrease DMT, slow starts and bimodality.
Investigate individual cows with lower milk speed
When slower milkings are limited, faster take-off settings can be an optimization step to improve milking efficiency.
Delayed take off high conductivity
Delayed take off on high conductivity delays the take off moment by adding extra seconds when conductivity of one quarter is increased. Delayed take off on high conductivity gets activated when the conductivity increase is 10% or higher. A CDT deviation of 10 – 50% results in a proportionally, delayed take-off level of up to 16 seconds extra.
This setting could be an option to enable when udder health problems occur on a farm. However, it is recommended to keep it as default ‘off’ because it can create more force on the teats. The ‘pre-set’ take-off settings are normally sufficient to milk out quarters completely without overmilking. When CTO is enabled with shorter take off settings than Quick take-off, it is recommended to be switched on.
Take home message
The impact of take-off settings is bigger on milkings with low milk speed and milkings with a slow end. Try to identify the root cause of lower milk speed or slow ending milkings. If build-up of congestion earlier in the milking due to e.g. bimodality or lower milk yield causes slow ending milkings, try to solve this before adjusting take-off settings.
Quick Take-off is the recommended take-off setting to milk completely without overmilking. CTO settings can be used to optimize the milking process further if e.g. milk access and pre-treatment are optimized. Always follow-up if shorter CTO settings are used.
Take-off settings can have a big influence on the quality of the milking process. Multiple different take-off settings are available in Horizon, and selecting the right take-off setting contributes to a complete milking in the shortest time.
For more information or questions, contact your FMS Specialist
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