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Animals-Milk


Milk is a complex compound which is made up
of fats ) in the form of emulsion or small
floating particles (,proteins ) in the form
of suspension ( and a specific kind of suger
called lactose ) in the form of a true
solution (.In addition to the ingredients
mentioned which form the basic compenents of
milk some minerals especially calcium and
phosphorous,vitamins and a variety of organic
elements are somehow present in the compound.
The use of this nutrient especially goes back
to the domestication of cattle between 0006
and 8000 B.C. Inscriptions show that dairying
was carried on during the Sumerion era
( around 6000 B.C.(.Indians were raisers of
cattle as early as 2000 B.C.,and the butter
obtained used as food and a holy offering to
the gods.Egyptians,too,used milk,butter and
cheese extensively about 3000 years B.C.
Reports indicate that in Greece and Rome milk
and cheese formed a major part of the diet of
the people 1550 and 750 B.C.respectively.
Divine books such as the Old Testament and
the Qur'an contain references to cattle and
milk.The Old Testament has fourty references
to cattle;milk and milk products were also
very desirable foods and have at least been
referred to for fifty times.



Today milk is the best known natural nutrient
and is the sole source of food for new born
mamals.Today cattle are the primary producers
of milk in the world , producing %91 of the
world's supply. Dairy cattle are the best
convertors of plant protein into animal ones.
Milk is very important in the human diet
because of two principal ingredients: protein
and calcium.Consumption of 1 liter of milk
daily can supply most of the essential food
requirements such as calcium,vitamin d,
riboflavin and many other minerals and
vitamins.



Milk is now consumed in a variety of ways
such as different kinds of butter and cheese,
milk powder,cream,low-fat milk and skim milk
and different kinds of ice cream.It is worth
saying that percapita milk consumption in the
world in the years 1978 to 1980 was 107 kg.
It has been reported that it was 386.6 kg
in European Economic Community,48.7 kg in
souther Asia, 19.9 kg in eastern Asia ,and
7.2 kg in central Asia.



How milk is produced in mamals,which is one
of the mysteries of creation,is taken up in
cows since it is of great importance.
The udder in cows consists,in fact,of four
distinctive big glands.Milk is drawn from
the nipple of each of the glands which are
located on lower part of the udder.Each one
of the four udder glands is in fact a complex
cluster-like gland which consists of
secretory units or small grape-like objects
called asini or alveoli.Each of these small
bubbles ) alveolus ( has a small duct that
leads into larger ducts. Every 150 to 220
alveoli pour their secreted material in one
duct and form a cluster named lobule which
measure roughly 0.75 m. m^3. A number of
lobules come together to form a lobe.In fact
udder is made up of lobes which are attached
to the duct system . All these units are
surrounded by a specialized tissue . Every
alveolus is supplied with a number of small
capillaries and venuoles which supply blood
to the alveolus and drain away unused blood.
In a minute,between %20 to %30 of the blood
pumped by the heard enterns the udder which
return to the heart after passing through the
alveoli.Every milk producing small bubble
( alveolus ( is surrounded by a collection of
specialized covering cells called epithelium.
These cells absorb nutrients from capilaries
and convert prerequisites ) materials taken
from blood ( into milk ingredients,and during
the milking period pass milk into the middle
lumen of the alveoli,small ducts,then,carry
the milk to larger ducts and it is finally
carried to a portion of the udder called
sinus galactophore.



Epithelial cells of the alveoli are the main
elements responsible for milk secretion.Each
ingredient of milk is produced and combined
in a specific process by these cells. The
nucleus of these cells issue the necessary
information for the production of proteins
and other activities.Epithelial cells of
alveoli absorb some of the fat building units
from blood and produce some others inside the
cells;the end product of this process is milk
fat . The sugar entering the udder from blood
is converted into lactose ) milk sugar )
through some processes.These processes are
seemingly carried on in the golgi apparatus
of epithelial cells . Minerals and vitamins
in milk are derived through the purification
of blood , and all these ingredients are
finally directed into alveoli in the form of
a compound liquid called milk.
A highly productive dairy cattle yield up to
70 liters of milk in 24 hours.

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