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Dairy Cattle Production(95314)

Milking machines and milking dairy cows

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Milking process

Objectives:

1. Milk cows efficiently

2. Maintain udder health (prevent udder infection)

3. Produce milk of high quality

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Steps of milking

1. Clean the udder with clean towel 2. Predip (20-30 sec).3. Take streak of milk from each teat and examine for

abnormal milk5. Dry teats with individual towel6. Attach machine7. Adjust and monitor milk flow8. Make sure cow is milked out (avoid overmilking)9. Shut off vacuum when done and remove machine 10. Postdip

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Important notes

• Avoid making noise• Wear gloves• Only milk clean, dry teats• Don’t use the same cloth to clean several cows

spread of infection• Avoid liner slips

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Teat dipping

• Keep teat dip clean and throw out if it becomes contaminated with manure or dirt.

• Teat dip should cover ½ to ¾ of the teat • Allow time for the teats to dry before cows exit the

barn

• Dip teats immediately after milking.

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Teat Dipper

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Under and Overmilking

• Undermilking– Imcomplete removal of milk– Too much milk left in udder begins to dry off cow

• Overmilking – Leaving the machine on after milk flow stops– Does more damage than undermilking

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Signs of overmilking

• Discolored teats after milking• Teats with ringing at the base after the unit is

removed• Cows become restless or start to kick during late-flow

period• Claws or long milk hoses without any milk

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Normal teat

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Bacteria Count With Different Preparation Procedures

Udder Preparation Bacteria Count

No Preparation 17,100

Wash Udder, Hose, No Dry 19,500

Wash Teats, Wet Towel, No Dry

5,000

Wash Teats, Wet Towel, Dry

2,100

Dip Teats, Dry 2,900

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Lactocorder

• Used for monitoring people and machine performance

• Accurate meter• Measures flow from cow

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Good milk flow

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Bimodal milk flow: Poor udder Stimulation

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Overmilking

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Unbalanced Udder

All Quarters Milking

2 Quarters Milking

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Suckling• A suckling calf uses vacuum as opposed to pressure to

extract milk from the gland and teat canal. • When a sufficiently strong suction (vacuum) is applied at

the tip of a teat, the pressure outside the teat is lower than inside and the milk is drawn out.

• A suckling calf wraps its tongue and roof of the mouth around the teat. A vacuum is created at the tip of the teat when the jaws widen and the tongue retracts toward the throat. As a result, milk accumulates in the mouth.

• When the calf swallows the milk, its flow from the teat stops because the pressure inside the mouth returns to normal (80 and 120 alternating suck and swallow cycles occur per minute)

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Milking machine

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Components of a milking machineThese include:1. A vacuum system: vacuum pump and reserve tank,

vacuum regulator, pipelines and long pulse tube(s) forming an enclosed space

2. Pulsators that alter the vacuum level around the teat so that milking occurs without fluid congestion and edema of the teat tissues

3. Milking units or cluster: the assembly of four teatcups connected to a claw and mounted with a valve that admits and cuts off the vacuum to the unit

4. A milk removal system that transport the milk away from the milking unit toward a storage unit: the milk tube and receiver (bucket, recorder jar, milk pipelines, milk pump, etc.).

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Vacuum Pump• Heart of of the system• Generates the vacuum that:

– Removes the milk – Massages the teat– Moves the milk

• Sized for the number of units– How much air can they pull from system?

• Degree of vacuum measured in inches of mercury or Kilo Pascal (1 mm Hg = 0.1333 Kpa)

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Pulsator • The pulsator is a simple valve that admits air and

vacuum alternatively in the pulsation chamber of a teatcup.

• Pulsators may be activated by vacuum or an electrical signal from a pulsator controller to give a frequency of 45 to 65 cycles per minute (pulsation rate).

• The pulsation is simultaneous when all four pulsation chambers of the milking unit are in the same position at the same time (all four at the milking phase at the same time, and all four in the massaging phase at the same time). With the alternating action, two of the teat cups are milking while the other two are massaging.

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Milking Unit (Teat Cup Cluster)

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Cluster or milking unit

• The liner inside the teatcups of the milking unit is the only part of the machine that comes in contact with the udder of the cow.

• Thus the weight of the unit is usually adjusted to the vacuum level to provide the desired tension on the teat to allow proper positioning and adequate milking action.

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• If the vacuum level inside the unit is too high or the unit is too light, the following may occur:

1. The unit “creeps up” and tends to pinch the area where the teat meets the udder.

2. Milk flow stops and the operator must pull down the unit to completely milk out the cow;

3. Teat lesions are more likely, making the cow more susceptible to mastitis;

4. Teat congestion increases, which tends to decrease the size of the teat canal and the speed of milking.

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When the vacuum is too low or when the milking unit is too heavy the following may occur:

1. The milking unit falls off easily;

2. A weak seal between the teat and the liner leads to more frequent slippage and admission of air in the unit, creating undesired vacuum fluctuations and greater risk of spreading mastitis;

3. The speed of milking is reduced.

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• During milking, the flow rate may range from 2 to 5 kg of milk/minute for a period of 2-8 minutes depending on milk yield.

• Thus the design of the cluster is important to ensure that milk flow is not restricted.

• In addition, good visibility of milk flow is important because it allows the operator to make sure the unit is properly adjusted at the beginning of milking and to identify the end of milking easily.

• Over-used liners decrease milking speed and increase the risk of spreading mastitis. Thus they should be replaced periodically.

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How does a milking machine works?

• The milking machine also uses vacuum to extract milk from the udder.

• If the vacuum applied to a teat is too high or lasts too long, blood and body fluid will accumulate and the resulting congestion of the tissue will stop milk flow.

• When a milking machine is used, the double chambered teatcup and the pulsator allow the teats to be subjected alternately to a vacuum (milking phase) and to atmospheric pressure (massage phase).

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• When air is removed from the pulsation chamber (area between the shell and the liner or inflation), the liner opens because the pressure inside the chamber and the pressure inside the vacuum line are the same. The vacuum at the end of the teat forces the milk out of the teat cistern into the line.

• However, when air is admitted inside the pulsation chamber the liner collapses beneath the teat (because the pressure inside the liner is lower than inside the pulsation chamber). During this period of “rest,” the teat canal closes (but not the teat cistern), milk flow stops, and the body fluids that were “aspirated” in the tissue of the teat may leave. This massaging action of the teatcup during a pulsation cycle prevents fluid congestion and edema of the teat.

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Pulsation Cycle

Phases: a = opening phase, b = milking phase, c = closing phase, d = massage phase

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• Typically, the liner of a milking machine opens and closes 45 to 65 times a minute (pulsation rate).

• In a pulsation cycle, the milking phase is usually equal or longer than the massage phase. The percentage of time of a pulsation cycle spent on each phase is referred to as the pulsator ratio.

• For example, a 60:40 pulsator ratio means that the vacuum is increasing or at maximum vacuum for 60% of the cycle and decreasing and/or at atmospheric pressure for 40 percent.

• For example, assuming a pulsation rate of 60 (one pulsation cycle per second), a pulsator ratio of 60:40 indicates that the milking phase lasts 0.6 second and the massage phase lasts 0.4 second.

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Effect of ratio on milking speedAverage flow, lb/min.

Ratio Average Flow

60 : 40 7.31a

65 : 35 7.65b

70 : 30 7.81c

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Effect of vacuum on milking speedAverage flow, lb/min.

Vacuum, inHg. Flow Rate

12.5 7.22a

13.5 7.52b

14.5 8.02c

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Wave Forms in Vacuum Chamber