If you’ve ever heard an older farmer in your area bemoan, “They don’t make liners like they used to”, well it’s true.

In fact the liners made today are better in many respects than they used to be – many are softer, they don’t need ‘breaking in’, and have design features to improve cow comfort during milking.

However the feature most people tend to notice is that they don’t last for as many milkings. The working-life of liners is less than it was a decade ago because they now contain less carbon black (a component that increases rubber’s resistance to wear and tear, but is less suitable for food-producing systems).

This means that liners need to be replaced more frequently, which is a not such a bad thing from a mastitis prevention point of view.

Liners deteriorate with age and use – they lose tension, absorb fat from the milk and develop microscopic pits and cracks. The cracks can hold bacteria, and as the number of bacteria increases so does the risk of mastitis.

Deterioration is accelerated by cleaning (both the cleaning agents used and the temperature of the water), ozone given off by motors, and other factors such as ultraviolet light. The last example means that even unused liners age when they are stored in places exposed to sunlight!

Liners in good condition do not carry as many bacteria as liners that are nearing the end of their useful life.

So how frequently should they be changed? If you can see visible changes in the surface of the liner it is way too late. Most manufacturers recommend that rubber liners should be replaced after every 2,000 – 2,500 cow milkings.

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“Wash and wear ages liners”