“If you notice a difference when you change liners, the old ones were on too long” says Professor Graeme Mein from the University of Melbourne.

As liners age and lose tension it takes longer to milk the cows and milking can be less efficient, leaving higher volumes of milk in the teat ducts and cistern. There are several reasons for this.

1. The massaging of teat tissues during milking relies on rubber liners retaining their elasticity so they can collapse back into their original shape each pulsation cycle. If massage is not effective, fluid drawn into the teat tissue under vacuum causes the teats to swell and restricts milk flow through the teat canal.
2. Cows with sore teats are uncomfortable and this may interfere with their let-down.
3. The mouthpiece of older liners gets ‘sloppy’ so the liners tend to ride higher on the teats and this can hinder milk flow into the teat.

Another consequence of using liners for too many milkings is the increased risk of teat end damage and concurrent mastitis infection. Subtle and progressive damage can occur over several weeks and may only be detected by careful examination and scoring of teat ends.

The easiest way to avoid the problems of old liners is to change them regularly. How long rubber liners will last in your shed depends on factors such as:

• The number of cows milking

• How many times a day you milk

• The number of milking units in the shed.

An example calculation in the Countdown Downunder Farm Guidelines for Mastitis Control shows how to estimate liner life for your shed.

Time-management tip: A good way of keeping up-to-date is to mark the date for the NEXT liner replacement on your calendar on the day that you change the liners. Weekly liner checks are also useful for detecting ‘one-off’ problems such split or twisted liners.

Image and caption

Toon7 (no caption necessary), “Measure liner life in ‘cow milkings’ box on FG page 36 (no caption necessary)

Countdown Downunder Farm Guideline or Technote
Farm Guideline 6.3

Keywords
liners, pulsation, teat end health

Word length
315