nice way to clear your doubts

3. 1. What is milk…..
2. Composition of milk.
3. Factors affecting composition of milk.
CONTENTS

4. WHAT IS MILK……
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for
infant mammals (including humans who breastfeed) before they are able to digest other types of food. Early-
lactation milk contains colostrum, which carries the mother's antibodies to its young and can reduce the risk of
many diseases. It contains many other nutrients including protein and lactose.
India is the world's largest producer of milk, and is the leading exporter of skimmed milk powder, yet it exports few other
milk products. The ever increasing rise in domestic demand for dairy products and a large demand-supply gap could lead to
India being a net importer of dairy products in the future. The United States, India, China and Brazil are the world's largest
exporters of milk and milk products. China and Russia were the world's largest importers of milk and milk products until
2016 when both countries became self-sufficient, contributing to a worldwide glut of milk.

6. Milk is an emulsion or colloid of butterfat globules within a water-based fluid that contains dissolved
carbohydrates and protein aggregates with minerals. Because it is produced as a food source for the young, all of its
contents provide benefits for growth. The principal requirements are energy (lipids, lactose, and protein),
biosynthesis of non-essential amino acids supplied by proteins (essential amino acids and amino groups), essential
fatty acids, vitamins and inorganic elements, and water.
1.pH of milk:-
The pH of milk ranges from 6.4 to 6.8 and it changes over time. Milk from other bovines and non-bovine mammals
varies in composition, but has a similar pH.
2.LIPIDS:-
Initially milk fat is secreted in the form of a fat globule surrounded by a membrane. Each fat globule is composed
almost entirely of triacylglycerol's and is surrounded by a membrane consisting of complex lipids such as
phospholipids, along with proteins. These act as emulsifiers which keep the individual globules from coalescing
and protect the contents of these globules from various enzymes in the fluid portion of the milk.
COMPOSITION OF MILK:-

7. 3.PROTEINS:-
NORMAL BOVINE MILK CONTAINS 30–35 GRAMS OF PROTEIN PER LITRE OF WHICH ABOUT 80% IS ARRANGED
IN CASEIN MICELLES. TOTAL PROTEINS IN MILK REPRESENT 3.2% OF ITS COMPOSITION.
4.CASEINS:-
THE LARGEST STRUCTURES IN THE FLUID PORTION OF THE MILK ARE "CASEIN MICELLES": AGGREGATES OF
SEVERAL THOUSAND PROTEIN MOLECULES WITH SUPERFICIAL RESEMBLANCE TO A SURFACTANT MICELLE,
BONDED WITH THE HELP OF NANOMETRE-SCALE PARTICLES OF CALCIUM PHOSPHATE. MOST OF THE CASEIN
PROTEINS ARE BOUND INTO THE MICELLES. THERE ARE SEVERAL COMPETING THEORIES REGARDING THE
PRECISE STRUCTURE OF THE MICELLES, BUT THEY SHARE ONE IMPORTANT FEATURE: THE OUTERMOST
LAYER CONSISTS OF STRANDS OF ONE TYPE OF PROTEIN, K-CASEIN, REACHING OUT FROM THE BODY OF
THE MICELLE INTO THE SURROUNDING FLUID. THESE KAPPA-CASEIN MOLECULES ALL HAVE A NEGATIVE
ELECTRICAL CHARGE AND THEREFORE REPEL EACH OTHER, KEEPING THE MICELLES SEPARATED UNDER
NORMAL CONDITIONS AND IN A STABLE COLLOIDAL SUSPENSION IN THE WATER-BASED SURROUNDING FLUID.
MILK CONTAINS DOZENS OF OTHER TYPES OF PROTEINS BESIDE CASEINS AND INCLUDING ENZYMES. THESE
OTHER PROTEINS ARE MORE WATER-SOLUBLE THAN CASEINS AND DO NOT FORM LARGER STRUCTURES.
BECAUSE THE PROTEINS REMAIN SUSPENDED IN WHEY REMAINING WHEN CASEINS COAGULATE INTO
CURDS, THEY ARE COLLECTIVELY KNOWN AS WHEY PROTEINS. WHEY PROTEINS MAKE UP APPROXIMATELY
20% OF THE PROTEIN IN MILK BY WEIGHT. LACTOGLOBULIN IS THE MOST COMMON WHEY PROTEIN BY A
LARGE MARGIN.

8. 5.SALTS, MINERALS, AND VITAMINS :-
MINERALS OR MILK SALTS, ARE TRADITIONAL NAMES FOR A VARIETY OF CATIONS AND ANIONS WITHIN BOVINE
MILK. CALCIUM, PHOSPHATE, MAGNESIUM, SODIUM, POTASSIUM, CITRATE, AND CHLORINE ARE ALL INCLUDED
AS MINERALS AND THEY TYPICALLY OCCUR AT CONCENTRATION OF 5–40 MM. THE MILK SALTS STRONGLY
INTERACT WITH CASEIN, MOST NOTABLY CALCIUM PHOSPHATE. IT IS PRESENT IN EXCESS AND OFTEN, MUCH
GREATER EXCESS OF SOLUBILITY OF SOLID CALCIUM PHOSPHATE. IN ADDITION TO CALCIUM, MILK IS A GOOD
SOURCE OF MANY OTHER VITAMINS. VITAMINS A, B6, B12, C, D, K, E, THIAMINE, NIACIN, BIOTIN, RIBOFLAVIN,
FOLATES, AND PANTOTHENIC ACID ARE ALL PRESENT IN MILK.
6.CALCIUM PHOSPHATE STRUCTURE :-
FOR MANY YEARS THE MOST ACCEPTED THEORY OF THE STRUCTURE OF A MICELLE WAS THAT IT WAS
COMPOSED OF SPHERICAL CASEIN AGGREGATES, CALLED SUBMICELLES, THAT WERE HELD TOGETHER BY
CALCIUM PHOSPHATE LINKAGES. HOWEVER, THERE ARE TWO RECENT MODELS OF THE CASEIN MICELLE
THAT REFUTE THE DISTINCT MICELLULAR STRUCTURES WITHIN THE MICELLE.

9. FACTORS AFFECTING COMPOSITION OF
MILK:-

11. Normal Sources of Variation in Composition
Genetics and Environment
Table 1 contains the breed averages for percentage of milk fat, total protein, true protein and total solids.
A change in milk composition using traditional breeding techniques occurs slowly, although new
techniques of genetic manipulation may allow faster progress in the future. Yields of milk, fat, protein
and total solids are not easily impacted by genetics; heritability estimates for yield are relatively low at
about 0.25.
Table 1. Breed averages for percentages of milk fat, total protein,true protein and total solids

12. Milk fat percentages
COW BREED Approximate percentage
1.JERSEY 5.2
2.ZEBU 4.7
3.BROWN SWISS 4.0
4.HOLSTEIN FRIESIAN 3.6
These compositions vary by breed, animal, and point in the lactation period.

13. 2.Somatic cell counts
Table 2. Change in milk constituents associated with elevated somatic cell counts

14. 3.Stage of Lactation:-
The concentration of milk fat and protein is highest in early and late lactation and lowest during peak milk
production through midlactation. Normally, an increase in milk yield is followed by a decrease in the percentages of
milk fat and protein, while the yields of these constituents remain unchanged or increase.
4.Disease:-
Although other diseases can affect milk component content and distribution, mastitis has been the predominant
disease studied. Table 2 shows the compositional changes in milk constituents associated with elevated somatic
cell counts (a measure of severity of the disease). Mastitis results in a reduction in fat and casein content and an
increase in whey content of milk. These changes in the milk proteins, in conjunction with alterations in lactose,
mineral content and milk pH, result in lower cheese yields and altered manufacturing properties. Milk from cows
with elevated somatic cell counts (greater than 500,000 somatic cells/ml) has longer coagulation time and forms
weaker curds milk from cows with lower somatic cell counts.

15. 5.Season:-
Milk fat and protein percentages are highest during the fall and winter and lowest during the spring
and summer. This variation is related to changes in both the types of feed available and climatic
conditions. Lush spring pastures low in fibre depress milk fat. Hot weather and high humidity
decrease dry matter intake and increase feed sorting, resulting in lower forage and fibre intake.
6.Age (Parity):-
While milk fat content remains relatively constant, milk protein content gradually decreases with
advancing age. A survey of Holstein Dairy Herd Improvement Association (DHIA) lactation records
indicates that milk protein content typically decreases 0.10 to 0.15 unit over a period of five or more
lactations or approximately 0.02 to 0.05 unit per lactation.

16. 7.Maximizing Rumen Function Can Increase Milk Components:-
There are several strategies that producers can use to enhance rumen function and the resulting milk components.
Producers who use records, such as those provided by DHIA, can critically evaluate their nutrition and feeding
management programs.
8.Feed Intake:-
It is critical to maximize feed intake of cattle so that negative energy balance is minimized during early lactation. As
cows consume more energy than they use, body weight is regained, losses in body condition are minimized and
cows produce milk of normal fat and protein content. Increasing feed intake, and the resulting overall increase in
energy, can increase milk protein content by 0.2 to 0.3 percent.. Major factors that can affect feed intake include:
• • Feeding frequency
• Feed sequencing
• Social interactions and grouping strategy of the herd
• Abrupt ration changes
• Physical facilities
• Environmental temperature

17. 9.Grain Feeding:-
The proper feeding of concentrates involves maintaining proper foragetoconcentrate ratios and
nonfiber carbohydrate levels. Feeding appropriate nonfibre carbohydrate levels can improve both milk
fat and protein levels, while overfeeding leads to milk fat depression of one unit or more and often
increases milk protein percent by 0.2 to 0.3 unit.
Table 3. Grain feeding guidelines

18. Reference:-
– Wikipedia
– Quora.com
– Milkfacts.info

19. Compiled by:-
Bishal Barman