Silicone teat liner portfolio expanded with Scala: which teat liner should I choose?

Recently, the Scala teat liner has been added to the silicone teat liner portfolio. With the addition of the Scala teat liner, a gap has been filled in the portfolio that was identified based on teat measurements done by FMS and other colleagues worldwide in the field. Overall, teat sizes are getting smaller and more teats fall in between the Classic and the Comfort teat liner. The Scala can handle a variety of teat sizes due to the flexible head design. Additionally, the narrower head design can improve connection performance for narrow positioned teats compared to the Classic teat liner. But when do you select the Scala teat liner and how do you evaluate whether the selected teat liner is the best match for the herd?

Figure 1: Positioning of the Astronaut silicone teat liner types

Figure 2: The different head designs of the Astronaut silicone teat liner types, high head for Classic, Flexible head for Scala and low head for Comfort.

Teat liner choice and complete milking

Teat liner fit remains of utmost importance when selecting a teat liner, as the teat liner is the link between the cow and the Astronaut. Teat liner choice can have a significant impact on the completeness of the milking, by affecting precise attaching, preventing congestion, and ensuring accurate take-off at the end of milking.

Figure 3: Circle of improving milking performance.

Figure 4: Square milk flow profile, indicating a complete milking.

How does the teat liner affect attaching and take-off performance?

A complete milking can only be achieved if the teat liner is successfully attached until milk flow ceases. Teat liner choice should contribute to precise connection performance and accurate end of milk flow detection. In automatic milking, the teat liner should accommodate slight misalignment of the teat cup and teats during connection to prevent folding of the teats. When the teat liner lip is too rigid or too narrow, folding of the teats is more likely to happen. This results in higher Dead Milk Times (DMT) and a higher number of connection attempts. A flexible lip with a fitting diameter helps in precise and quick connection performance. On the other hand, at the end of milking, a tight lip is required to facilitate accurate end of milk flow detection and prevent too early take-off based on airflow. Thus, a fitting teat liner facilitates the different needs at the beginning and end of milking.

Figure 5: Different needs at the start and end of milking

Can congestion be prevented by choosing a different teat liner?

One of the main functions of a teat liner is to massage the teats to prevent congestion build-up and provide relief during milking. Congestion caused by impaired liner fit is mainly linked to two parameters:

• Insufficient massage of the teats is most obvious when teats are too short for the depth of the head of the selected teat liner. When the depth of the head is too much, the teat will not reach deep enough in the barrel of the teat liner where the actual massage is done during the D-phase. This will continuously expose the teat to higher vacuum levels without providing relief in the D-phase.

• Too tight lip diameter is another risk of congestion imposed by the teat liner when teats are thicker. In this way, recirculation of lymph fluids and blood between the teat and udder is blocked, resulting in oedema that is “trapped” at the teat base and constricting the teat canal. 

What can teat measurements tell me?

A teat size measurement provides insight into the distribution of teat sizes on the farm and the average teat size. This helps to define if the herd predominantly has smaller, average, or larger teat dimensions for diameter and length. These insights are a good starting point to select a teat liner that should work best with the average teat size of all cows. With the addition of the Scala teat liner, the flow chart for teat liner choice has been updated as well. The Scala fits for average teat sizes and offers extra opportunities to optimise milking performance and deal with variation in the range of 21-22 mm diameter. It is expected that the Scala teat liner will work well for farmers that currently use the Classic 21 teat liner.

Figure 6: Updated teat liner flow chart.

Teat diameter

Information on teat diameter provides insight into which lip opening diameter might be most suitable. The lip creates a seal between the teat liner and the teat, and thereby keeps the teat cup attached. When the lip is too narrow, attaching the teat cup can cause some difficulties resulting in the teat cup being attached only to the lower half of the teat. Another effect of a lip opening that is too narrow is signs of ringing on the teats after milking.

Figure 7: Different teat diameters

Teat length

The length of the teat helps in determining which head size to use. For effective milking, being comfortable for the cow and complete, adequate massage should be applied to the teats during milking. If the teat is too short for the teat liner head, the teat will not be able to stretch into the liner barrel, resulting in congested teats and uncomfortable and incomplete milkings.

Figure 8: Different teat lengths

However, teat liner choice will always be a compromise, and selecting the teat liner based on average teat size of the herd means that for some cows the liner does not fit perfectly. Therefore, reviewing of the selected teat liner and adjusting, if necessary, remains important after selecting a teat liner based on teat measurements.

What can I check to evaluate teat liner choice?

Distribution of teat dimensions can vary greatly between different cows in the same herd or group. A skewed distribution or a large variation can be reasons to deviate from the teat liner advice based on average teat dimension. In these cases, a choice should be made about which (group of) cows to facilitate and what are acceptable trade-offs for other cows. Reviewing the selected teat liner and adjusting if necessary remains important after selecting a teat liner based on teat measurements.

What does the data tell me about teat liner fit?

After a change of teat liner type, LSSA can be checked to see if connection performance or take-off reasons were impacted. If these parameters are negatively impacted, evaluate if specific cows cause the issue, review the distribution of teat sizes, or follow up with a dynamic test. Another parameter of interest can be milk speed. Milk speed is the result of doing many steps of the milking process right. A teat liner will not solve issues related to milkings with lower milk yield, bimodality, or overmilking. If the teat liner does not bring the expected results, it is important to check other parameters as well and adjust if necessary.

What do cow signals tell me?

When the milking is finished, the teats should look in good condition. Especially swelling and ringing with discolourations are signals that the teat liner or milk settings do not meet the needs of the cows. Ringing and swelling due to constricting the teat base could indicate that a larger lip diameter is needed. Swelling of the teat could indicate that insufficient massage is applied or that mouthpiece chamber vacuum is too high (> 20 kPa). In both cases, a lower head type might be beneficial.

Normal teats after milking with optimal milking performance

·     Slightly wrinkled, soft teat skin, even color & dry teat

·     No swelling, no red or blue discolorations

·     ‘Orange peel’-like texture

Can a dynamic test help?

A dynamic test provides insight into the vacuum dynamics near the teat. When the variables are out of scope, it may be necessary to adjust milk settings or switch to a different teat liner. Two variables are of specific interest in relation to teat liner fit:

• Mouthpiece chamber vacuum during peak flow that is too high (>20 kPa) is an indication that the head is too high, resulting in a teat that is not properly massaged, or the lip is too small. When the lip is too small, the teat cannot fully enter the liner, resulting in the liner being attached to the lower part of the teat.

• Irregular vacuum fluctuations should be a maximum of 2 per milking. If this is exceeded, check for liner slip and consider a different teat liner.

Right shell for optimal performance

To reach optimal performance, the right teat liner-shell combination is important. The Scala teat liner is designed for the D-shell.

A-shell Classic teat liner / US rubber teat liner

B-shell Comfort teat liner

C-shell EU rubber teat liner

D-shell Scala teat liner

Take home message

With the addition of the Scala teat liner to the silicone teat liner portfolio, an all-round option is added for average teat sizes, whereas the Classic teat liner focuses on average to large-sized teats and the Comfort teat liner focuses on smaller-sized teats respectively. A teat measurement gives a direction on which teat liner to use, but it is important to follow up and evaluate the choice based on the distribution of teat sizes in the herd, teat signals after milking, and KPIs. A dynamic test can provide further insight when optimizing teat liner fit. The teat liner is the link between the Astronaut and the cow. Selecting the right fitting teat liner contributes to a complete milking for every cow, every time that she is milked in the Astronaut!

This is the current Lely portfolio of silicone liners. In some situations, the Lely rubber liner may also be a suitable option—your local FMS team can advise you on whether it fits your operation. If you would like to verify the liner configuration installed in your robots, your FMS team can provide the necessary tools, or you can request that they complete the check for you.

A dynamic test is included in the EXCEL level of the FMS Support Agreement. Producers outside that level can still request a dynamic test through their FMS team at West Coast Robotics or through their local Lely Center if they are outside British Columbia.