The milk liner is the only part of the milking machine that comes into direct contact with the cow so their condition is critical for mastitis control and efficient milking. Over time, worn liners reduce milking performance, decreasing the speed and completeness of milking, increasing teat end damage and the spread of bacteria that cause mastitis. Liners lose their elasticity and collapse as rubber deteriorates naturally over time. The rubber in the liners also disimproves with exposure to cleaning products used for machine disinfection. When liners become worn, they take longer to open but will close early due to their tendency to collapse under vacuum.
Have you changed your liners?
By: Tom McTague
CellCheck Team
Infected liners
The interior of the liner can also become rough causing small tears in skin of the teat which makes cleaning and disinfection difficult, allowing bacteria to build up. One infected liner can infect at least 8 cows in the milking cycle. The industry recommendation is to change liners after 2,000 milkings or 6 months, whichever comes first. It is important to check the inside of the liners regularly to see if they are soft and smooth or rough and cracked.
One infected liner can infect at least 8 cows in the milking cycle.
The choice of liner used is very important in reducing teat damage and any increase in mastitis incidence, and should be chosen in consultation with your milking machine technician. A well aligned good quality liner should fit the teat cup shell as it must collapse fully around the base of the teat. If not, blood will not be able to circulate leading to teat end swelling (oedema), damage resulting in ‘wedging’ at the top of the teat (left image) or abnormal amounts of ‘ringing’ at the base of the teat (right image).
When to change liners
The liner also needs to have a soft flexible mouthpiece that forms an airtight seal with the base of the teat adjacent to the udder. This minimises liner slip and cluster fall off. Poor contact can take place in cows with small, very large or splayed teats or heifers with turgid teats due to excessive udder swelling.
To work out exactly the number of days between liner changes, simply complete the following calculation.
2000 x no. of milking units
Herd size x milkings per day
For example, if you are milking 100 cows in a 12-unit milking parlour twice a day, liners should be changed every 120 days.
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