Principles of milking

HYGIENIC MILKING & HANDLING
Milking:
 Is the act of collecting milk released from a
cow‟s udder after proper stimulation of a cow.
Milking is a team effort in which the cow, the
machine and the operator (or the calf) play
important roles.

MILK LET-DOWN…
A large amount of the milk accumulates within
the alveoli between milkings.
The milk let-down starts with the activation of
nerves whose impulses are interpreted by the
brain (hypothalamus) to signal the cow that
milking is about to happen.

MILK LET-DOWN…
One or a combination of external stimuli may
initiate the milk let-down:
a) The physical touch of a calf or that of an
operator cleaning the teats.
a) The sight of a calf
a) The sound of a milking machine.

MILK LET-DOWN…
When a cow is stimulated, the brain sends a
signal to the posterior pituitary gland that
releases the oxytocin hormone into the blood
stream.
The blood conveys the oxytocin hormone to the
udder where it stimulates the contraction of the
myoepithelial cells surrounding the milk-filled
alveoli.
.

MILK LET-DOWN…
Normally, contractions of the myoepithelial cells
occur 20 to 60 seconds after stimulation.
The squeezing action increases the
intramammary pressure and forces the milk
through the ducts to the gland and teat cistern.

MILK LET-DOWN…
The action of oxytocin only lasts for six to eight
minutes as its concentration in the blood
decreases quickly.
It is important to attach the teatcups (or begin
hand milking) one to two minutes after starting
udder preparation.
A delayed attachment reduces the amount of milk
harvested.

INHIBITION OF MILK LET-DOWN
When this occurs, the milk is not released
from the alveoli and only a small fraction
can be collected.
When pain, excitement or fear occur at
milking, nerve impulses are sent to the
adrenal gland .

INHIBITION OF MILK LET-DOWN…
The adrenal gland releases adrenaline hormone
which tighten the blood vessels and capillaries in
the udder.
The decreased blood flow decreases the amount
of oxytocin reaching the udder.
Also adrenaline seems to inhibit the contraction
of the myoepithelial cells in the udder directly.

HARVESTING MILK FROM THE UDDER
The opening at the tip of the teat is held closed
sphincter muscles.
Milk in the gland and teat cistern does not leave
the teat without an external force to overcome
the strength of the sphincter muscles.

HARVESTING MILK FROM THE UDDER…
A difference in pressure between the inside and
outside of the teat is usually needed to open the
sphincter and let the milk flow.
Milk is routinely removed from the udder by
a) A suckling calf;
b) Hand-milking; or
c) Machine milking.

HAND MILKING
Hand milking uses pressure
The hand grasps the whole length of the teat.
The thumb and forefinger pinch off the upper end
of the teat as the other fingers squeeze inward and
downward
The increased pressure inside the teat
forces the milk through the sphincter

HAND MILKING…
During hand milking, the pressure inside the teat
becomes higher than outside the teat.

GOOD HAND MILKING PRACTICES
1. MILKING ENVIRONMENT
Milking should be done in a shaded place, which
is clean and dry.
The animal, milker, utensils and the
surroundings should be clean.

GOOD HAND MILKING PRACTICES…
Milking should be carried out in a quiet and
calm surrounding, undisturbed by anything what
is unusual.
Avoid smoking.
Do not cough sneeze or spit
Do not have long nails

2. RESTRAINING THE COW
Put concentrates in the feed trough before
bringing the cow into the milking place.
Kindly restrain the hind legs and tail of the cow
with a rope.
Do not beat the cow nor shout at her.
Avoid exciting the cow.

Restrained cow

3. UDDER PREPARATION
Wash the udder with a clean clean
cloth/towel and warm water.
Dry and massage the udder with a clean, dry
cloth/towel.
Trim the hair of the udder and the tail twice
per year to facilitate cleaning.

GOOD HAND MILKING
PRACTICES…
Cleaning the udder with a cloth/towel

4. CHECK FOR MASTITIS
Milk the first drops from each teat into a strip cup
or on any black surface to observe milk clots.
Discard these first drops, Do not add it to the
other milk.
If clots are observed from the teat, milk that
quarter last and keep that milk separate.

Cows with mastitis should be milked last and
their milk discarded.
Milk from cows under antibiotic treatment
should not be sold until 3 days after last
treatment or as advised by the veterinary
practitioner.

Check for mastitis using strip cup

5. PROPER MILKING TECHNIQUE
 Wash your hand with soap and clean water
before milking.
Do not milk if you are suffering from
communicable diseases like diarrhea or
typhoid, but seek medical treatment and
resume milking after full recovery.
Sit on the right side of the cow

Take hold of the base of the teat and
squeeze with thumb and forefinger.
Close the other 3 fingers and squeeze them
in turn to push the milk downwards and
expel it.

Never do “strip milking” by pulling the teat
between your thumb and your forefinger.
Strip milking can cause injury to the teat.
Establish a calm regular milking routine.

Milk at a 12 hour interval at the same times of
the day.
Milk quickly and make sure you empty the
udder at each milking within 7 – 8 minutes.
Release the cow from the milking area as soon
as milking is finished

Proper milking technique

6. TEAT DIPPING
After milking rinse each teat in an antiseptic teat
dip, udder wash or 2% lugol‟s iodine to prevent
mastitis.

7. MILK HANDLING
Weigh/measure the milk of each cow.
Sieve the milk through a trainer cloth to remove solid
particles that may have fallen in during milking
Keep the milk can closed and keep it in a cool place
Never add the milk of a cow, which is under treatment
or add colostrum with normal milk.

Milk handling(Sieve)

8. CLEANING EQUIPMENT
Use stainless steel equipment with a
smooth surface.
The surface of plastic material easily gets
scratches and then cannot be cleaned
properly anymore.

All utensils must be washed immediately after
milking
Pre-rinse the container soon after use
Thoroughly scrub the container with warm water
and detergent or soap by using a stiff bristled
hand brush
Rinse the container in a clean running.

Dip rinse the container in boiling water for
at least one minute to kill germs. You may
also rinse the container by pouring hot
water into it.
Place the container upside down on a rack
above the ground and let it dry in the sun

Cleaning equipments

MACHINE MILKING
Is a machine for harvesting milk from the udders
of animals(ie.cows, goats, sheep).
Milk harvesting is the process of:
 Extracting milk from animals
 Transporting the milk to a storage tank
 Cooling and Storing the milk until it is picked
up for processing.

MACHINE MILKING…
Milk harvesting:
Milk harvest requires cooperative effort between
:
 The animal
 The operator
 Properly functioning milking machine

Goals of Milking Machine
A properly designed, installed, maintained, and
operated milking machine will:
 Remove milk from the animal quickly and
gently
 Not contribute to poor udder health
 Not degrade milk quality from the time of
removal to delivery
 Be easy to clean and sanitize

A milking machine is made up of several basic
component groups and essential parts include:
 A vacuum pump,
 A vacuum vessel,
 A vessel for collecting milk,
 Teat cups and a
 Pulsator
Components of Milking Machine

Essential parts of milking machine

The milking unit is made up of several parts
 Teat cups
A soft rubber liner that is mounted in a metal
or plastic shell
The soft rubber liner is the only part of the
machine that touches the udder
 The claw
Collect milk from all of the teatcups
The milking unit

 The Pulsator
An air valve that creates „pulsation‟ or the
opening and closing of the liner
 Connecting tubes
Short milk tube = liner to claw
Long milk tube = claw to milk line
Short pulse tube = shell to air fork
Long pulse tube = air fork to pulsator
The milking unit

How the milk get out of a cow
The teat cup unit consists of a teat cup
containing an inner tube of rubber, called the teat
cup liner.
The inside of the liner, in contact with the teat, is
subjected to a constant vacuum of about 50 Kilo
Pascal(kPa) (50% vacuum) during milking.

How the milk get out of a cow…
The pressure between the liner and teat cup is
regularly alternated by the pulsator between kpa
during the suction phase and atmospheric
pressure during the massage phase.

How the milk get out of a cow
The pressure in the pulsation chamber (between
the liner and teat cup) is regularly alternated by
the pulsator between 50 kPa during the suction
phase and atmospheric pressure during the
massage phase.
The result is that milk is sucked from the teat
cistern during the suction phase.
During the massage phase, the teat cup liner is
pressed together allowing a period of teat
massage

How the milk get out of a cow
Relief of the teat during the massage phase is
needed to avoid accumulation of blood and
fluid in the teat.
Congestion in the teat can be painful to the
cow, and milk let down and milking
performance can be affected.

How the milk get out of a cow
Repeated congestion at successive milking
sessions can even have an influence on the
udder health.
The pulsator alternates between suction and
massage phases about 50 to 60 times per
minute.
The four teat cups, attached to a manifold called
the milk claw, are held on the cow‟s teats by
suction and the friction between the teat and the
teat cup liner.

 How the milk get out of a cow
Vacuum is alternately (alternate pulsation)
applied to the left and right teats or, in some
instances, to the front teats and rear teats.
The applying of vacuum to all four teats at the
same time (simultaneous pulsation) is less
common. The milk is drawn from the teats
directly to the milk pail or via a vacuumised
transport pipe to a receiver unit.

 How the milk get out of a cow
An automatic shut-off valve operates to prevent
dirt from being drawn into the system if a teat
cup should fall off during milking.
 After the cow has been milked, the milk pail is
taken to a milk room where it is emptied into a
churn or a special milk tank for cooling.

AUTOMATIC MILKING SYSTEMS…
Automatic milking systems, have been installed
on commercial farms at an increasing rate in
recent years.
The potential benefits of automatic milking
machine include:
 Reduced labour requirements,
 Higher milk quality,
 Improved animal health and
 Increased yield.

AUTOMATIC MILKING SYSTEMS
A typically dairy farm layout with an automatic
milking system.

In conventional milking, people bring the cows
to be milked while automatic milking places
emphasis on the cow‟s tendency to be milked in
a self-service manner several times a day.
When the cow wants to be milked, she
walks to the milking station.

A transponder on the cow identifies it, and if
the cow was milked recently, she is directed
back to the resting or feeding area.
The cow enters the automatic milking station
and an individual amount of concentrate is
served.

The teats can be detected by a laser and vision
camera and can be cleaned separately by means
of a teat-cup-like device, using tepid water
applied intermittently at a certain pressure and
turbulence to ensure efficient cleaning.
Drying of the teats is carried out by compressed
air in the same teat-cup.

Fore milking is done by the cleaning teat-cup,
which applies vacuum at the end of the cleaning
cycle.
The cleaning teat-cups are finally flushed with
water.
Sensors can detect whether fore milking has been
carried out.
Fore milking is applied for a few seconds to
ensure that sufficient milk is evacuated and the
let-down reflex is activated.

The teat-cups for milking are automatically
attached sequentially.
Milk from the four teats is kept separate until the
milk meter records the amount from each quarter.
 Spraying each individual teat with a disinfectant
is carried out at the final stage of milking.

During milking the following are recorded:
 Milk yield,
 Milking duration,
 Milk flow rate,
 Cow movements
 Time of milking
 Time of concentrate feeding

Milk leaving the milking station is divided into the
following categories:
Treated cow
Freshly calved cow (colostrum)
Cow with less than one milking in the last 24
hours
 A cow which, although healthy, has cell
counts above a certain level.
Fresh milk is forwarded to a buffer tank for cooling
before being pumped to the storage tank.

CLEANING AND SANITISING
For hand and bucket machine milking manual
cleaning with brushes is a common method used.
In pipe line milking plants, milking circulation
cleaning is commonly performed.
The cleaning solution is circulated through the
plant by vacuum and/or a pump.

COOLING OF MILK ON THE FARM
Milk leaves the udder at a temperature of about 37
°C.
Milk should therefore be cooled immediately after
it leaves the cow.
It is important to keep the milk at low temperature
during storage.
The activity of the micro-organisms will easily
increase again if the temperature is allowed to rise
some few degrees above recommended storage
temperature.

BACTERIAL DEVELOPMENT IN RAW MILK
Milk should preferably be cooled to 4 °C as soon
as it is produced and then kept at that temperature
until processed.
Psychrotrophic (mainly occur in soil and water),
can grow and reproduce below +7 °C.
Psychrotrophic bacteria will grow in raw milk
stored at 4 °C. After an acclimatisation period of
48 – 72 hours,

The influence of temperature on bacterial
development in raw milk.
BACTERIAL DEVELOPMENT IN RAW MILK…

BACTERIAL DEVELOPMENT IN RAW MILK…
After an acclimatisation period of 48 – 72
hours,growth goes into an intense logarithmic
phase.
This results in breakdown of both fat and protein
of the milk.
This might be an important reason for off
flavours that may jeopardise the quality of
products made from the milk.
This phenomenon must be taken into account in
the planning of collection schedules.

BACTERIA GROWTH AT 4°C IN RAW MILK

Principles of milking

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