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Composition of Milk

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Rural Technology

Milk Constituents

The major constituents of milk are Water, Fat, Protein, Lactose, Ash or Mineral matter. The minor constituents of milk are phospholipids, sterols, vitamins, enzymes, pigments etc.

Average chemical composition of milk:

Factors affecting composition of milk

Milk differs widely in composition. All milks contain the same kind of constituents but in varying amounts. Milk from individual cows shows greater variation than mixed herd milk. In general, milk fat shows the greatest daily variation, and then comes protein followed by ash and sugar.

Species of animal:

Each species of animal yield milk of a characteristic composition.

Breed :

The milk of some breeds of same species is comparatively higher in fat content than those of the other breeds e.g. Milk of Red Sindhi cow contains higher fat than those of H.F and Brown Swiss.

Individual variation :

Individuality of the animals is responsible for some of the greatest variations in the composition of milk.

Stage of Lactation :

The period from the time the calf is born until the cow ceases to give milk is called period of lactation. The secretion of milk immediately after calving is known as colostrum. It may last from 3 to 6 days. It contains more protein and more total solids than those of normal milk.

Age :

The fat content in milk rises from 1st to 3rd lactation period, then it remains fairly constant in subsequent lactation periods but later towards advancing age there is slight reduction in the fat content of the milk.

Seasonal Variation :

Generally, fat and Solids-not fat content in milk show slight but well defined variations during the whole year.

First and last milk :

There is a considerable variation in the fat content of the fore milk, mid milk and stripping. The fore milk is very poor in fat and stripping are very rich in fat. This variation is more when the milk yield is high.

Feed of the animal :

When the milch animals are given sufficient balanced ration, feed has no significant effect on composition. When the feeding is changed there is some variation in the composition of milk but such variations are temporary.

Interval of milking :

In general, a longer interval is associated with more milk and lower fat test.

Frequency of Milking :

Whether a cow is milked two or three times a day, it has no great effect on the fat test.

Physical condition of the animal :

There may be a change in the composition of the milk if the animal is suffering from any disease viz. in the milk of cow or buffalo suffering from mastitis there is reduction in fat, protein, lactose content and marked increase in chlorides content.

Environment at the time of milking :

Anything which causes discontentment and uneasiness in the cow at the time of milking causes the cow to be nervous and leads to the holding up of her milk. As last portion of milk is rich in fat, hence it affects the composition.

Administration of drugs and hormones :

Certain drugs may affect temporary change in the fat percentage, injection or feeding of hormones results in increase of both milk yield and fat percentage.

Milker :

If the milker is not an efficient one and not able to draw milk completely from the udder, the fat content of the milk is reduced.

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Fill in the blanks:

  1. Milk fat.......... is the constituent of milk.
  2. The first secretion obtained after calving of animal is called as...................
  3. Vitamin is.......... the constituent of milk.
  4. The........... milk contains less milk fat.
  5. Longer interval of milking is associated with............... milk.
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