02 June 2025

Teat liners – time for a change?

Teat liners - time for a change?

Over the next few weeks, Padraig O’Connor writes, the teat liners will need to be changed in most spring-calving dairy herds. This will depend on the parlour size, the number of milkings per day and the number of cows being milked through the parlour.

The milking machine is the most important machine on a dairy farm and its maintenance is vital for safe and efficient milking. As part of this maintenance, the teat liners need to be changed regularly.

The teat liner is the only part of the milking machine that comes in contact with the cow; their condition and design is critical for udder health, mastitis control and efficient milking.

Recommendations

The recommendation is to change liners after 2,000 milkings or six months, whichever comes first. Over time, worn liners reduce milking performance and decrease the speed and completeness of milking. Worn liners can also potentially increase teat end damage and the spread of mastitis-causing bacteria. Liners lose their elasticity as rubber deteriorates naturally over time. When liners become worn, they take longer to open and close on the cow’s teats while milking.

Milk liners are also exposed to hot water and detergents/acids daily and, over time, this will also have an impact on the effectiveness and efficiency of the liner.

Figure 1 illustrates a worn cut-away liner with a build-up of milkstone. This will cause the liner to become rough, causing small tears in the skin of the teat. This will also make cleaning and disinfecting these liners more difficult, allowing bacteria to build up in the liners, which may lead to higher bacterial counts, thermoduric counts and somatic cell counts.

Figure 1: Image of worn liner with a build-up of milkstone

Guide to estimating number of days for 2,000 milkings

To calculate the number of days:

Firstly, multiply 2,000 by the number of milking units (A);
Secondly, multiply the herd size by the numbers of milkings per day (B)
Divide A and B = number of days

For example, the following calculation applies to a herd of 120 cows milking twice a day in a 14-unit swing over parlour:

A: 2,000 multiplied by 14 = 28,000
B: 120 multiplied by 2 = 240
Divide A and B: 28,000 divided by 240 = 116 days

The example above indicates that the liners, in this case, need to be changed after 116 days.

Replacing liners

When replacing liners, ensure that they are a good quality liner, compatible with the liner shells, and that they fit properly. The liner needs to have a soft, flexible mouthpiece that forms an airtight seal with the base of the teat next to the udder. This will reduce liner slip and cluster fall off. It is also recommended to wash and clean the inside of the liner shells before fitting the new liners. Ensure that the new liners are not twisted after fitting and the liner markings are aligned as outlined in Figure 2. This is also a good time to inspect the other rubberware in the parlour.

Figure 2: Liner markings

Conclusions

Teat cup liners in the milking machine are the equivalent of tyres in a car. They play a critical role as they are constantly in motion during the milking process. Therefore, it is one of the most active parts of the milking machine. They also have to withstand the effects of cleaning agents and high-water temperatures. Worn liners lose their shape and don’t massage the cow’s teats properly, leading to poor and inefficient milk out. Worn liners also harbour bacteria and will have a negative impact on Somatic Cell Counts, Total Bacterial Counts and Thermoduric counts.

Now is the time to check out the date for teat liner change for your farm!

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