- INTRODUCTION
Rapidly advancing technological development demands that a farmer keep abreast of the latest technological developments in his profession. The dairy farmer should also keep pace with modern developments in his profession, for this is the only way in which he can move with the times and ensure the success of his farming enterprise. It is hoped, in a subsequent series of lectures, to highlight some of the important features of machine milking.
2. PLANNING A MILKING MACHINE SYSTEM
A milking machine system should be regarded as a unit comprising the dairy building and milking machine. It is proposed to show how a milking machine installation can ensure an efficient milking action. But most of these requirements, in turn, make certain demands on the building in which the milking machine is housed. This emphasises how risky it is to erect the building first and then choose the milking machine. It can result in chaos and inefficient milking. The design of the building affects the design and cost of the milking machine and vice-versa. For this reason, it is essential that buildings and machine should be well matched so that the system functions efficiently as a unit.
Let us first consider our reason for wanting to mechanise the milking process on the farm. The reasons why more farmers are investing in Milking Machines are as follows:
3. THE ADVANTAGES OF MECHANICAL MILKING
LABOUR
Utilisation
With a well-planned milking machine system, up to 30 cows per man per hour can be milked. Whereas the average for milking by hand is only 6 cows per man per hour.
Problems
Some farmers have difficulty in finding sufficient labour and this problem may well increase in the future. Dairy farmers in particular have problems with weekend labour. Milking Machines make it possible for the farmers to manage with fewer but more skilled labourers, and if need be, even to do the work themselves.
Time Saving
Mechanical milking goes hand-in-hand with time saving and consequently, reduction of costs. Machine-milking takes less time, thereby making the labourers available for other tasks on the farm.
Hygiene
In a modern milking machine system, milk is automatically conveyed to the milk room and has great possibilities for hygienic milk production. However, it should be emphasised that the supervisor and the operator must pay careful attention to correct handling and cleansing of systems.
Cost Saving
The labour-saving achieved with milking machines gives you considerable cost savings. The efficiency of the system is the highest in compact milking parlours, which are cheaper to build and maintain than the ordinary old-fashioned, long milking sheds.
Operating Convenience
A good split-level milking parlour system is less fatiguing, since the labourers operating the milking machine units can stand upright while they work and need not move to and fro so often. This enables them to do their work with greater efficiency.
Constant Milking Action
The consistency of the milking action is one of the most important requirements for efficient milk removal from the cow. This consistency can be achieved when a good milking machine is used and is properly operated and maintained.
Milk Quality
The hygienic quality of the milk can be more easily maintained with a good machine, when thorough care is exercised in its handling and cleaning.
Neatness
A compact dairy building is easier to maintain and keep clean. This creates an impression of neatness.
Capital Recovery for the Installation
The capital invested in a new milking machine system can be recovered from the resulting saving of labour. Actual labour saving should, therefore, be an important goal of mechanical milking at all times.
Milking machines, properly managed, can contribute much by way of increasing milk quality. Additional recovery of capital could also be gained from selling quality milk.
4. COMPONENTS OF A MILKING MACHINE SYSTEM
Before the requirements for a functional, efficient milking machine system can be discussed, one must have a clear understanding of the various components of the milking machine, as well as how they function together in facilitating the milking action of the cow.
Vacuum Pump
Milk is removed from the cow by applying suction on the teats. The suction is obtained by means of a vacuum pump which continually removes air from the milking system.
Figure 1: Cross Section through a Cluster
Normal pressure in the system is 350mm of mercury i.e. a vacuum.
Teat cups and Liners
The suction on the teats, whereby milk is removed from the udder, is applied by means of elastic liners held in position by rigid metal teat cups. Each liner tapers into a short milk tube at the bottom. (See figure 1: of a section through a cluster).
Claw-piece or beaker-cup
The four short milk tubes gather in a claw piece or a large beaker-cup, from which the milk is transported through a thicker milk tube to a bucket, can, recording jar or a milk pipeline. Some claw- pieces are fitted with a valve in order to shut off the milking vacuum to the teats while in other cases a pinch-clip on tap in the milk tube fulfils this function.
In the case of the suspended bucket machines, the four short milk tubes directly enter the lid of the bucket and no claw-piece or beaker-cup is used.
Cluster
The 4 teat cups, liners and short milk tubes, together with the claw-piece, beaker-cup or bucket (suspended), 4 short pulsator tubes and the milk tube together form the cluster.
Pulsator
Continuous suction on the teats would hinder blood circulation in the tissue to such an extent that it would irritate the cow and lead to damaged tissue. To prevent this damage, suction on the teats must be intermittent, and this is achieved by means of a pulsator, which lets air from the atmosphere into the space between the liner and the teat cup whereby the liner walls collapse against the teats. This action produces the rest phase of the pulsator cycle during which blood circulation is restored.
The rest phase is followed by the milking phase, during which the pulsator provides vacuum to the space between the liner and the teat cup. During this phase, the liners open up and milk can flow from the teats. (The pulsator effect is illustrated in the figure 1).
The time ratio between the milking phase and the resting phase is known as the Milk-Rest Ratio, and the number or pulsation cycles per minute is known as the pulsation rate.
- Normal Milk-Rest Ratios vary between 1:1 and 3:1.
- Pulsation Rates usually vary between 50 and 60 per minute.
Vacuum Controller
Vacuum pumps used on milking machine systems are capable of maintaining a vacuum level much higher than that which is safe for the cow. Therefore, vacuum controller has the important function of ensuring that the vacuum level in the milking machine system remains constant and at a safe value all the time. The controller does this by admitting outside air into the system. The correct functioning of this controller is of the utmost importance for udder health.
The controllers are normally adjusted to maintain the vacuum level at a constant value within the range 330 – 380mm of mercury.
Vacuum Gauge
The prevailing level existing in a milking machine system is indicated by this gauge. Should fluctuations or vacuum shortages occur in the system, the meter should indicate it. It is obvious that the correct functioning of the meter is of greatest importance.
Sanitary Trap
This component is mounted close to the vacuum pump and is part of the vacuum supply system. It fulfils the following functions. It protects the vacuum pump against the inflow of liquids such as milk, water or cleaning fluids. It also acts as damper against small vacuum fluctuations in the main vacuum supply.
Releaser
This apparatus separates the milk from the vacuum and releases the milk for cooling and storage. The Releaser usually consists of a Receiving Jar sanitary trap and a pneumatic or electrical milk pump. The electric milk pump is also used in the cleaning process of the milking machine.
Pipelines
A variety of pipelines used in a milking machine system for the distribution of vacuum, transport of milk and the circulation of cleaning fluids. The materials used for these pipelines are galvanised steel, stainless steel, heat resistant glass and plastic.
Figure 2: A milking machine system
5. CHOOSING A SYSTEM
The choice between various milking machine systems depends on the circumstances on each farm.
When choosing a milking machine system, it must be decided whether to retain a good existing milking shed, or whether a new milking parlour.
Together with the planning of the new milking parlour, the outside must be given serious consideration. This includes the following:
- Holding kraals (pens);
- Approaches and;
- Feeding points: this must be done only after a good feeding procedure has been established.
If existing buildings are going to be used, the farmer is going to be restricted as to what system he is going to install. On the other hand, the system is going to depend largely on the size of the dairy herd and the farmer’s policy.
PLANNING OF SIZE
When planning the size of a milking machine system, calculations should be based on one milker handling only two clusters or 3 at the most. This is recommended mainly to avoid over- milking.
It is important to plan the size of the milk parlour and the number of clusters entailed in terms of the number of labourers. This plan will keep the total milking time within limits.
It is usually preferred to limit the milking time to a maximum of two hours. The number of cows per labourer per hour (cows/man hour) which could be milked in a particular system must be estimated. The following figures give an indication of the values from which the estimates can be made.
Tandem Parlours must not be greater than a 6-row single point or a double row 12 point. In large systems too much time is wasted by movement of cows. The optimum size is a single- row, 4 point, or double-row, 8 point tandem system.
Example: Calculation of the size of a tandem parlour for a herd of 100 cows with a desired milking time of 2 hours.
- Assume: Labour figure of 25 cows/man hour
- Each labourer has two clusters With a single row tandem parlour:
- 2 labourers
- 4 clusters
It would, therefore, be possible to milk 50 cows in 60 minutes and 100 cows in 120 minutes.
A third labourer will be necessary to record the milk yield and to control the entrance door. These tasks can be conducted by the supervisor.
It must be emphasised that the labour figures which will be attained in practice will depend mainly on the following:
- Proper labour organisation;
- Proper training of labour;
- Well-considered planning of holding kraals and approaches;
- Regular supervision and;
- Cows that are accustomed to the system
Other requirements include an estimate of the costs involved for the different systems Note that this information changes all the time, and once you have elected what system you are going to follow, then go for the best bargain you can get.
Also take into consideration
- Feed-hoppers and troughs
- Udder sprayers
- Back-flushing of clusters between successive cows
SOME MILKING SYSTEMS
Normal Cowshed
Each cow has its own stall in the cowshed where it is milked and fed. Milking is done using milking buckets or by the pipeline system which carries the milk directly to the cooler and into the milk churns. The dairy is situated at one end of the milking shed. A normal shed holds 50 cows and larger herds can be milked on the batch system.
Figure 3: Normal Cowshed
Abreast Milking Parlour
Cows come in from a collecting yard and after milking go out into another yard. Milking can be by bucket, pipeline or directly into a milk can.
Figure 4: Abreast Milking Parlour
Herringbone Parlour
The milker stands in a pit between the two rows of cows. He washes the udders of the cows on one side and puts on the milking clusters. While those cows are being milked, he washes the udders of the cows on the other side. This type of parlour can house 4 cows at a time or up to 50 cows, with 25 on each side.
Figure 5: Herringbone Parlour
