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Lely's Free Cow Traffic principle allows each cow to reach her full potential by being milked at a frequency that corresponds to her needs. Although Lely applies this principle, it does not mean cows are milked every time they visit the Astronaut milking robot. Allowing a cow to be milked every time she visits the Astronaut milking robot would be damaging to the cow and an inefficient use of the robot. The milk access table in Lely Horizon determines whether a cow is allowed to be milked. A cow goes through different stages in her lactation, each with different needs. This affects the milk yield during lactation. Horizon’s milking allowance during a lactation is divided into three phases with different goals in the milk access table (see figure 1).
All heifers and some cows in early in lactation need to learn how to be milked in a Free Cow Traffic system. Giving cows more access at this phase increases the positive incentive needed to motivate cows to visit the robot voluntary. In this lactation phase, cows increase their milk production and need to be milked more frequently than a cow in late lactation to avoid limiting her potential milk production due to udder fill. A high frequency of milkings provides the opportunity to consume small meals of high-energy concentrate in the robot to reduce the risk of rumen acidosis.
A cow in mid lactation needs an incentive to maintain persistent milk production for as long as possible. With the right settings, a balance can be found between giving more access to higher producing cows and adequate access to lower producing cows. There is a wider range between the maximum and minimum number of milkings to give milk access based on the cow's expected milk yield.
A cow in late lactation will have significantly lower milk production and therefore needs fewer milkings. Reducing the number of milkings per day prepares her for a successful dry off with less risk of udder inflammation. The number of minimum and maximum milkings is reduced in this phase to increase udder fill, which gradually reduces the rate of milk production by the udder.
How to set up the milk access table?
As a starting point, Lely aims that cows are milked approximately 3 times per day. The optimum expected yield per milking for a herd is calculated by dividing the average milk yield per day by three. In the case of a herd average of 27kg (59,5lbs.), the optimum expected yield for mid lactation is 9kg (19,8lbs.), 27 / 3 = 9 (59,5 / 3 = 19,8lbs.). The optimum yield for the early lactation phase is -1kg compared to mid lactation phase to allow cows to be milked more often, and late lactation +1kg to refuse a cow earlier
Lely aims to milk cows that are expected to give 8 – 12kg (17,6 lbs. – 26,5 lbs.). This range is recommended during the start-up period. A lower or higher yield per milking correlates with an increased SCC or Free Fatty Acid issues. To optimise higher yielding herds, we recommend the herd average divided by 3, which can be higher than 12kg (26,5 lbs.).
Lely recommends a maximum number of milkings of 5.0 per day. If a cow is milked more often, this can have a negative impact on the teat condition, udder health, and milk quality. For minimum number of milkings, 2.0 milkings per day is recommended to allow every cow access at least twice a day. The minimum and maximum number of milkings are the safety net, setting the right optimum expected milk yield is key.
It is possible to set up different milk access tables for different groups. Lely recommends setting a separate milk access table for heifers. They have a lower milk production which requires different settings.
Deviating from the principles of the milk access can bring different consequences, which are briefly described in table 1 below
Changing the optimum expected yield per visit has a big influence on milking allowance. This parameter is the first criteria that is checked when providing cows access or not. Reducing the optimum yield means earlier access and vice versa. Lely recommends the average divided by 3 for the matching optimum expected yield, with a minimum of 8kg (17,6 lbs.).
The access given by the optimum expected yield per visit is still influenced by the set maximum and minimum of milkings per day. These are the hard limits restricting and granting cows access during a day. Increasing the maximum number of milkings will provide high producing cows that are limited by optimum expected yield more access. Decreasing this maximum will restrict these high producing cows and they will give more milk per milking, which can limit their udder fill. The minimum number of milkings have an influence on the lower producing cows and cows low in rank. Increasing this number will result in less refusals and more milkings. Decreasing the minimum will restrict their access, which in turn will refuse them earlier and might result in a higher yield per milking.
Shortening the early lactation will affect visit behavior in the beginning of the mid-lactation phase, because cows are refused earlier. Since the first phase is about training and motivating fresh cows, it is important that they are visiting the robot properly before they move to the mid-lactation phase. Above all, making the first phase shorter has a bigger impact on the daily concentrate intake per milkings in the beginning of the mid-lactation phase. The calculated daily concentrate is distributed over less milkings which could affect the rumen.
Extending the early lactation phase will result in cows reaching the optimum yield more often which results in more milkings per cow per day. Studies have shown an increased milking frequency results in a higher milk yield (Petterson et al., 2011) (Dahl et al., 2004). These studies concluded that due to a higher mammary gland development, the increase of yield carries over into the rest of the lactation. However, in free cow flow systems like the Astronaut, the increased early lactation period could result in fewer visits and therefore more fetch cows in mid-lactation
Optimising the number of days after calving can be done using graph 52 by setting the number of days after calving just after the peak of lactation, which allows open access for cows before peak production is reached and restricts access for lower yielding cows after the peak of lactation.
Making changes in the late lactation period will affect how much time the herd has to reduce in yield before dry-off. This depends per herd and how much they produce in the last days before dry-off. If this yield is too high, it is recommended to extend this late lactation period. However, the biggest impact on reducing milk yield can be made by limiting the concentrate intake earlier. Deviating from the recommended 14 days before dry-off should be the last step to fine-tune the milk access. This should only be done when the other criteria in the access table are optimized to the herd.
Alignment with other Horizon settings
When deviating from the milk access principles, not only the above-mentioned consequences need to be considered. Other settings within Horizon must also be aligned. If it is decided to change the days after calving period, the moment of feeding based on milk yield should also be checked in the feed table. At least two weeks need to pass between changes that may affect visit behavior and we recommend one change at a time. Cows should have limited number of changes in a short amount of time. The reward changes immediately for cows, and cows will react in less visit behavior.
The ‘Days in lactation’ number in the Collect Cows setting should also not be the same as the milk access ‘Days after calving’ number. The aim of having an increased start of lactation period of 60DIM for Collect Cows, is to ensure proper visit behavior while cows transition to production-based feeding and access. Every cow that appears in this task will have milk allowance. This task can help to gain insight in possible sick cows or cows that have not adjusted well enough to show voluntary visit behavior. Lely recommends using the default settings and only adjust Collect Cows settings to tune the fetch list and don’t misuse these settings to influence milk access. This must be done in the milk access table.
When and how to change the milk access table?
It can be the case changes are required to optimize the herd performance. The Horizon milk access tables need to be adjusted to meet challenges like variety in the seasons, the weather, the feed quality, the cow numbers, and other factors that affect cow change over time. Changing the milk access table must always be done in small steps, since this setting has influence on production, capacity, and health. When these steps should occur and how much change in the table each step includes, depends on the rate at which cows can adapt, farm status, and farm goals.
Research shows that cows will wait for an average of 15 minutes near the robot entryway before entering or leaving this area (Solano et al., 2022). The aim is to minimize waiting time to enhance cow comfort by reducing the risk for lameness, because longer waiting times is associated with shorter lying times. This is influenced by e.g., grouping primiparous cows and having a low stocking density of cows/robot, but also milk access.
When changing milking allowance, the average waiting time of cows must be considered. As example, increasing the optimum expected yield/milking for a 27kg herd from 9 to 9,5 in one step reduces access for another 30 minutes. The research of Solano et al. provides insight in cow behavior and a step of 30 minutes later access might be resulting in cows returning for milking too late, because they are refused earlier and will stop trying. A step of 0,2 in this instance results in 18 minutes later access
This is similar when changing the number of maximum milkings per day. Reducing from 5 to 4,5 milkings in one step changes the milking allowance to 29 minutes later. While a step of 0,2 to 4,8 will allow cows to be milked only 11 minutes later.
Drastic limitation of access increases the risk of cows giving up on visiting the robot due to too much negative reinforcement via increased refusals. Closely monitoring the impact of the change(s) made in the following days is therefore important.
Monitoring the milkings is done via reports ’35 – Milking – Visit Behavior’ or ’41 – Milking – Cow Robot Efficiency’. The focus in these reports should be on the average milk yield/milking which should be at least 8kg (17,6lbs.). If there are too many cows below this yield, check their lactation days, milk yield/day, visits, and refusals. This additional information might make the milk yield/visit acceptable or not.
Cows are individuals with their own rhythm and rank within the herd and will not visit the Astronaut milking robot exactly according to the allowance settings. The ability safely access available robots for milkings is monitored through Free Time. Free Time percentage should be acceptable to Lely’s standards (>10% & 15% for heifers). Before making another change, the number of cows to fetch per shift should also be back to Lely’s standards (<5/RU) or according to the farmer’s wishes. Report ’52 – Analyze – Cow Lactations’ may be used to visually check the balance between milkings, refusals and day production. In addition, this graph shows the persistency of the herd and thus impacts production and visit behavior.
The FMS FarmScan provides insight into visit behavior and milk intervals as well. Milk interval distribution can give a clear picture on the average interval length and milk yield per visit per lactation. It is advised to minimize short intervals, which can be done by decreasing access. When percentage of short interval and low yield is too high, it is advised to increase minimum number of milkings. When percentage of short interval and regular yield is too high, reviewing of the optimum yield per milking or maximum number of milkings might be necessary.
Exceptions & related settings
Horizon adapts to the cow’s natural visit frequency variability by granting access when the cow is within 90% of her allotment. By taking this natural variance in the cow’s schedule and to prevent a cow being refused although almost reaching the end of the minimum milk interval, this 90-% rule is in place. As example, if a cow is allowed for a maximum of three milkings a day, she can be milked every 8 hours. The 90%-rule grants milk access 7:12 hours after the previous milking. This prevents a cow visiting a robot close to the 8-hour interval being refused and not visiting the robot for multiple hours afterwards.
Milk access settings determine when a cow is allowed to be milked based on milk yield of that cow. The Collect Cows setting determines when a cow is brought to attention to the farmer on the fetch list. Cows on the fetch list always have access to be milked and therefore the collect cow settings overrule the milk access settings. When the number of milkings set at the collect cow settings is higher than minimum number of milkings in the milk access table, a cow might appear on the fetch list and granted access. This can be the case at the beginning of lactation when collect cow settings have a recommend 2.5 milkings for the first 60 days and the milk access changes to midlactation, with minimum 2 milkings, before 60 days.
The Grazeway and Cosmix solutions do not influence milk access, but rather Astronaut visits. This is related to their respected settings in allowing cows to graze and/or eat at the Cosmix. In Horizon’s milk access page, near to be milked intervals (%) can be set for both Grazeway and Cosmix, influencing when cows stay inside or should visit the Astronaut for concentrates.
Depending on how this is set in Horizon, it will have a small or big effect on visit behavior of cows into the Astronaut. Thus, the near to be milked intervals influence when cows must visit the Astronaut before allowing to go outside and/or eat at the Cosmix concentrate feeder.
How does milk access impact individual cows?
The milk access table is setup for a group of cows but has a different impact on every individual cow. Milk intervals are calculated based on the yield of the cow and limited by minimum or maximum number of milkings. In table 2 below are examples for three cows that are in the mid lactation phase
In table 2 above, three examples are provided, and the way their milk access is calculated is described. In addition, an Excel document is available that can be used to visualize other, practical, examples by yourself. This is the Milk access tool on the Knowledge Base. It helps in learning to understand what will happen on individual cow level when making certain changes to the access.
Conclusion
Since the Astronaut robot milks one cow at a time, only a limited number of milkings per day are possible. This means that milking access must be prioritised based on the cows' needs. This is done by focusing on the main stages of lactation, which require different access for milking. Early in lactation cows should be motivated to visit the robot voluntarily and allow cows to reach their potential milk production through more frequent milkings. In mid-lactation access is based on milk yield and there is a wider range for cows with higher and lower-yielding cows. Before drying off, cows are prepared for dry-off by lowering the yield with fewer milkings.
Deviating from the principles can have consequences for individual cows and changing access to correspond to the herd’s performance should be closely monitored. This is because milk access has a big influence on production, robot capacity, and health. Therefore, we recommend sticking to the basics and principles we shared.
For more information or questions, contact your FMS Specialist
Bibliography
Pettersson G., Svennersten-Sjaunja K., Knight C. (2011). Relationships between milking frequency, lactation persistency and milk yield in Swedish Red heifers and cows milked in a voluntary attendance automatic. Journal of Dairy Research, 78(3), 10.1017/S0022029911000471
Dahl G. E., Wallace R. L., Shanks R. D., and Lueking D. (2004). Effects of Frequent Milking in Early Lactation on Milk Yield and Udder Health. American Dairy Science Association, 87(4), 87:882–885
Solano L., Halbach C., Bennett T.B., and Cook N.B. (2022). Milking time behavior of dairy cows in a free-flow automated milking system. JDS Communications, 3(6) 426-430, 10.3168/jdsc.2022-0243
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