The most important component in a parlour is probably the milking cluster. The primary link between teat and tank, it is the action of the teat cups that largely dictates the efficiency of the milking process and also the health and welfare of the cows’ udders.
The key to proper operation of teat cups is to maintain a constant level of vacuum at the teat end – and this is not that easy to achieve, even in modern parlours. So it’s a good idea to check that the vacuum regulator is working correctly, with a vacuum of between -38kPa and -40kPa at the teat ends.
There can be other demands on the vacuum supply that work against maintaining a constant pressure – automatic cluster removal, gate-opening systems, milk metering and pumping systems all require their own vacuum supply.
Over a period of time, teat liners tend to lose their elasticity and become deformed, which affects their ability to work properly. A replacement interval of 2,500 milkings is considered to be about right – this would mean that 300 cows being milked through a 16×16 herringbone would need to change liners every four months.
A key check on the cluster is to ensure that the small air hole in the claw piece is not blocked. The primary task of the hole is to allow a flow of atmospheric air to enter and provide a “carrier” for the milk to flow away from the cluster. But it also has a stabilising effect on the vacuum level.
Should it become blocked, vacuum pressure will fall and the milk will back up in the cluster, risking cross-infection.
Other key things to check:
1. Maintaining the correct vacuum pressure is essential. The regulator automatically controls the pressure by bleeding in atmospheric air when required.
2. A large-capacity vacuum reservoir can help to create a stable pressure even when ACRs are in action and pneumatic gates are opened, although the latter could be on a separate system.
3. Modern vacuum pumps are designed to provide vacuum on demand rather than barking away at maximum output. They are more efficient as a result but still need to be maintained in terms of belts and lubrication.
4. Standby vacuum pumps, used when there is a power failure, need to be run up and tested on a regular basis.
5. Automatic washing systems are a useful addition to a dairy and can lead to earlier breakfasts but keep a check on their operation – particularly the rinsing cycles.
6. Cooler plates are used to cool the milk before it enters the tank. The better the job these do, the less the tank cooling system has to do. Make sure the flow of cooling water is adequate to cope with the volume of milk.
|7. Bulk tanks need to be able to hold milk at between 3C and 4C. Make regular checks to ensure this is the case and that the agitators are working correctly. A recalibration of the tank can be a useful exercise – a few litres a day can add up over the year.|
8. The milking cluster. Note the small hole in the claw, which allows air into the milk pipe so the milk flows away from the cluster. If it becomes blocked, milk will build up and cross-teat contamination will occur. There could also be problems with vacuum pressure.
Want advice on maintaining your milking parlour? All the main milking parlour manufacturers, as well as many equipment suppliers, will be at this year’s Livestock 2012 event on 4 and 5 September at the NEC.