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Since the 1950's Dutch dairy farmers have welcomed mechanical aids to reduce the manual effort required during the milking process. This started with the use of vacuumized milk buckets. The use of vacuum is still the fundamental technical principle of todays milking equipment, even for the computerized milking robots of the 21st century.
Although milk robots might be a promise for the future, at present they prove to be too costly and not trustworthy enough to dominate the market. One can seriously doubt whether they will ever make a break-through.
Nowadays there are several types of milking parlours in use. The most popular are the "Herringbone-type", the "Tandem-type", the "Rotary-type" and the hybrid "Rapid-exit-type". The choice for the appropriate type of parlour is mainly based on the size of the herd.
A milking system derives the milk from a cows udder and transports it to the cooling tank. It has to work fast, cow-friendly, trustworthy, accurately, hygienically, and user-friendly.
One can discern several sub-systems within a milking system.
The clawpiece and the teatcups are the basic elements of any milking system. During the milking process the 4 teats of a cows udder are enclosed in the 4 teatcups of the milking claw. The periodical squeezing and sucking motions of the clawpiece makes the cow release her milk.
The squeezing and sucking motions are enabled by the so-called pulsator, a ingenious device that uses the low airpressure provided by the vacuum system to simulate a calfs teat-sucking. Over the years the pulsating system has undergone many changes (not always improvements). Modern pulsators are steered electronically instead of mechanically.
A farmer is always eager to know how much a cow produces. When a cow does not feel well, that is reflected in the milk production immediately. A popular way to measure a cows production is the glass milk container. The milk that flows from the clawpiece is collected in the milk glass, which has a maximal measuring index of 28 or 32 litres.
Modern milking systems have a flow measuring device that gives an electronic reading of the production, eliminating the need for a glass container.
When a cow has emptied her udder, the clawpiece should be removed as soon as possible. When milking is prolonged systematically after the udder is empty, the udder will be damaged eventually.To ensure that this never happens, modern milking machines are equipped with automatic release systems. When the milk flow diminishes, the milk claw with the teatcups will be automatically released and lifted away from the udder.
The actual milking process is done in the "milking pit", a separate section in the stable where the farmer stands in a lower pit, and the cows on a normal level, bringing the udder to a convieniant working level for the farmer. Once the milk has been derived from the cows it has to be transported to the more hygienical environment of the milk room. This is done by a system of stainless steel piping, a collecting glass, and a milk pump. The milkflow from the cows is not a continous flow. Therefore it must be collected batchwise, before it can be pumped to the cooling tank. For hygienical reasons it is imperative that foaming effects, due to mixing of air and milk are prevented. The short resting time in the glass collection container separates air and milk, and the subsequent batchwise pumping of pure milk also reduces the chance of foaming effects.
Vacuum (or rather low-pressure air) is a vital element of milk retrieval. A constant level of low pressure is of great importance to an excellent milking process. The vacuum system consists of a vacuum pump, a vacuum resevoir, and a vacuum regulator. It is important that the capacity of the pump, and the size of the resevoir are large enough to assure a constant pressure level.
After the entire herd has been milked, the milking system needs to be cleaned thoroughly. The cleaning system uses hot and cold water and an acid or alkaline cleaning fluid, to rinse all the pipes, tubes and containers of the milking machine.
Modern milking machines are hooked up to a farm computer that monitors the production, behaviour, well-being of the herd. It gives warnings to the farmer, and regulates the food supply to each indivdual cow.
The essence of every milking system is the same, but there are many variations in the way the cattle moves through the milking pit. The most popular are the "Herringbone-type", the "Tandem-type", the "Rotary-type" and the hybrid "Rapid-exit-type". The choice for the appropriate type is mainly based on the size of the herd.
The Herringbone parlour is the most common and popular type of milking systems. It is recommended for all herd sizes. The cows gain access to the parlour in batches. The herringbone parlour guarantees a good throughput. The angle at which the cows are lined up can vary.
In the 32° parlour the teat cups can be applied from the side or between the cow's rear legs.
The 50° herringbone was designed specifically for rear leg milking. The cows stand nearer to the operator and the increased angle of the cow standing improves udder presentation allowing quick attachment of the clawpiece.
The Tandem milking parlour consists of individual stalls in line along the operator’s pit. The cows enter and exit in batches or individually. As soon as the milking is finished, the cow immediately leaves the stall and the next cow enters. It is the only modern milking system that can treat the cow as an individual. The tandem parlours are recommended for 40 to 110 cow herds.
The Rotary milking system is recommended for large herd sizes ( <150). It can be considered as a continuous herringbone parlour.The rotating parlour has a huge throughput. It allows cows with a slow milk release to stay in the parlour for two cycles if necessary.
In the Rapid-Exit parlour the cows are positioned side by side (perpendicular to the pit) and milked from the rear. The cows enter in batches. This system decreases the length of the parlour and therefore the operators walking time. At the front of the rapid exit parlour a pivoting yoke allows rapid release of the cows in one operation. This system is particularly recommended for large herds.
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