The udder receives nutrient-rich blood from the heart through blood and lymph vessels that distribute the blood to the capillaries surrounding the alveoli. The milk-producing cells within the alveoli are then furnished with the necessary nutrients for secreting milk. Once the cells are spent, the capillaries carry the blood away and return it to the heart.

1. Milk Biosynthesis
Mr. Muhammad Imtiaz

2. BIOSYNTHESIS OF MILK
• The whole udder is laced with blood and lymph
vessels.
• These bring nutrient-rich blood from the heart to
the udder, where it is distributed by capillaries
surrounding the alveoli.
• In this way, the milk-producing cells are
furnished with the necessary nutrients for the
secretion of milk.
• “Spent”blood is carried away by the capillaries to
veins and returned to the heart.

3. BIOSYNTHESIS OF MILK

25. Evolution of lactose content with the stage of lactation
0
5
10
15
20
25
0 50 100 150 200 250 300
Lactation stage, d
Milk
yield,
kg/d
42
43
44
45
46
47
48
49
Lactose
content,
g/kg
Milk yield Lactose content
Inra (1978)

26. Evolution of fat content with the stage of lactation
0
5
10
15
20
25
0 50 100 150 200 250 300
Lactation stage, d
Milk
yield,
kg/d
34
36
38
40
42
44
46
Fat
content,
g/kg
Milk yield Fat content
Inra (1978)

27. Evolution of protein content with the stage of lactation
0
5
10
15
20
25
0 50 100 150 200 250 300
Lactation stage, d
Milk
yield,
kg/d
30
32
34
36
38
40
42
Protein
content,
g/kg
Milk yield Protein content
Inra (1978)