Milk secretion is one of the most important physiological events in mammals that have given birth and entered the production phase. In this situation, the mammal gland becomes a real milk factory representing a considerable metabolic effort for the cow, which must consume excellent quality food so that, once digested, it becomes the precursor of each component of milk.

Lactation is a period that lasts about 10 months and comprises three defined stages: rise, peak production and persistence or decline, which culminates in the drying of the pregnant cow.

Most important components in milking systems

The synthesis of milk is a complex process carried out by the secretory cells of the alveoli, which, from precursors that circulate in the blood, such as sugars, fatty acids, proteins, minerals and vitamins synthesize the components of milk and with the addition of water through the intervention of lactose, pour the milk into the cavity of each alveoli that will discharge it into the system of ducts and finally to the cisterns of the mammary gland; at that point the milk is ready to be milked.

In the milk industry, the main objective is to obtain cow’s milk, taking advantage of the 10-month period of milk production of the cow. This is done by different milking methods, among which we can mention mechanical milking machines.

These milking machines extract the milk from the mammary gland of the cow by means of vacuum suction. Milking machines consist of several components that together are known as milking equipment.

Some of the most important components of this equipment are:

1. Vacuum pump: its main purpose is to generate a vacuum by sucking in air and expelling it.
2. Pipe or hose equipment: this equipment requires a system of hoses connected to the vacuum pump and other parts of the system such as pressure gauges, pushers and vacuum regulators. As part of this piping equipment, we can also mention the milk conductive ducts into which the hoses from the milking unit are fed.
3. Pulsators: are a key element for milking systems, as they give a suction time and a rest time, which is known as “milking massage”. Pulsators work thanks to the vacuum formed by the vacuum pump. They can be electromagnetic, hydro-pneumatic or pneumatic pulsators.
4. Milking claw: it is the part of the milking unit that meets the mammary gland of the cow. It consists of 4 plastic liners that are attached to each teat. These liners are connected to a receiver from which a hose comes out to take the milk to the cooling tanks by means of a pipe.
5. Vacuum regulators: maintain the vacuum level within the indicated parameters.
6. Manometers: they allow us to measure the vacuum inside the pipes. The measurement units for this type of instrument are inches of mercury.
7. Milk meters: within these we can find the proportional and the automatic electronics.
8. Milk receiver: usually these are stainless steel tanks of different capacities, where the milk arrives through the ducts and pipes, and is cooled for preservation.
9. Milk pump: its function is to intermittently remove the milk that reaches the receiver.
10. Washing unit.

In addition, we can find some variants of mechanical milking, including the pipeline that carries the milk and the buckets or drums.

The first case is a closed circuit of ducts that lead the milk to a refrigerated tank. The bucket system, on the other hand, can be seen in small systems where one or two machines feed the milk into drums or buckets.

Guidelines on the installation of milking systems

When installing a milking system using milk pipelines, we must take into account a number of guidelines to ensure proper installation.

These guidelines involve the following aspects:

• Capacity of the pumps: this should be adapted to the number of units and size of the room, which in turn is related to the length of the ducts.
• Pipe size: Both ducts and hoses must comply with recommended standards regarding their size according to the size of the installation.
• Slope: For good drainage or milk flow through the ducts to these pipes, it is necessary to install them with a slope towards the receiving unit.
• Vacuum reserve: Represented by the capacity of the regulators and vacuum reserve tanks.
• Type and size of hulls and liners.
• Characteristics of the pulsating system.

The modern method for milking milk is mechanical milking, which uses the suction force of a vacuum and, like a vacuum cleaner, draws the milk from each teat intermittently, so that the vacuum is not applied continuously, as this can damage the teat.

The milking vacuum is equivalent to half an atmosphere of pressure which is equivalent to 0.5 kg x cm² and which on a clock or analogue pressure gauge marks 15 inches of mercury, as the total atmospheric pressure is 30 inches of mercury at sea level according to Torricelli’s principle.

Type of milking systems

To achieve maximum performance in mechanical milking, a wide variety of systems have been developed depending on the needs of the dairy and the producer.

• Herringbone

It is the most common and traditional mechanical system; where the cows are placed in a row in the shape of a fishbone allowing a faster and continuous milking since, in this way, the cows enter their posts at the same time and are milked at the same time.

It is an economical system with a large capacity, having a yield of 8 to 10 cows per hour, as long as the producer organizes the batches of cows that will enter the system, organizing them in groups of the same amount of milk produced.

• Tandem

System of little diffusion among the dairy producers, where the cows are one after the other in individual cages, having independent entrance and exit, when one finishes, it goes out and is replaced by another one. Therefore, the set is an individual milking system that even allows milking with the calf next to the cow, to stimulate the milk flow.

It is a system that offers us several advantages, mainly the easy access to the udder, the careful observation of each cow and the reduction of the risk of accidents due to kicks. However, it is a system that takes up a lot of space for each milking point and has a high cost.

• Parallel

Also known as side by side, in this system both the entry and exit of cows is individual. The cows are arranged side by side and are placed on bars that prevent them from sticking their heads out while being milked.

Its design saves space and offers great comfort for the animals, as in many cases the feed is supplied to them at the time of milking. The operator stands behind it to start the milk extraction.

• Rotary or carousel

In this system the cows are arranged in a circular mechanism and are milked at the same time allowing a continuous cow traffic, where the operator only concentrates on the milking and not on the handling of the animals’ entry.

In this system the cows are in individual cubicles that together form a rotating circle. It should be considered that this is a costly system due to its design.

• Automatic or robotic

This is a highly innovative parlor for individual milking attention, where the cow enters a fully automated cubicle where she is milked with a robotic arm. This system is controlled from a screen.