What’s the risk with old liners?
The liner is the only component of the milking
machine that comes into direct contact with the cow’s teat. Therefore, it is one
of the key components in the process of milking cows quickly, gently and
completely.
Although many people try to squeeze a few more
weeks or months from the liners in a dairy, this is almost always a poor option
for the most important component of the milking machine.
As liners age, their shape, tension and surface
condition changes gradually. This gradual deterioration can have subtle but
significant effects on their milking characteristics. Both the internal surface
and the milking performance of liners tend to deteriorate more quickly soon
after they reach their designated use-by date.
As liners age and stretch, several key features
of their milking performance alters. In particular –
-
the average milking
time per cow increases
-
the frequency of
liner slips increases
-
the amount of milk
left in the quarters of an udder when cups are removed increases
-
the teat-end
condition of the cows decreases
-
cow behaviour
worsens
Whilst each of these features is associated with
an increased risk of mastitis, any effect on teat end condition or any increased
liner slips are particularly significant risks.
As a general rule of thumb, if you notice an
improvement in milking performance after replacing liners, the old ones were
used for too long!
The age of liners is calculated in terms of
“cow-milkings” and the Countdown Downunder Farm Guidelines show how to calculate
liner life in “cow-milkings”.
Most Australian rubber-based liners can be used
for 2,500 cow-milkings or 4-6 months – whichever comes sooner.
When renewing liners, always change all four
liners within a cluster at the same time to maintain similar mounting tension
and milking characteristics between the four teatcups.
Prevention is better than cure – change liners
according to their use-by date to avoid the risks from using worn out liners.
Image and
caption
"As liners age, their shape, tension and surface
condition changes gradually."
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