Dairy Farming Manual
|Why is knowing about the physiology of milk
production important? (5-8)
1 So you can improve your:
|What is your cow's udder like? (9-41)
2 The udder is a skin gland with four quarters and teats.
|Where does your milk come from?(42-46)
3 Cells in the udder take nutrients from the blood and produce milk substances.
|What affects milk production? (47-60)
4 Many factors in:
|5 Breeding affects milk production|
|6 but so do your feeding and management.|
|7 Knowing about the physiology of milk production helps you to improve your feeding and management|
|8 and to produce more high
quality milk and increase your income.
|9 The udder is a well developed skin gland.|
|10 It is like sweat glands and tear glands which also secrete fluids to the outside of the body (exogenous glands).|
|11 All female mammals have an udder for feeding their young|
|12 and your cow's long lactation period gives
milk for you as well as her calf.
|Outside the udder
Signs of a good udder are:
|14 The skin covers the
udder and protects it from rubbing and from bacteria.
But it is not strong enough to support the udder.
|15 Strong tissues called ligaments
help to suspend the udder.
Two bands run along each side of the udder.
|16 One band runs down the middle of the udder
between the right and left halves.
The middle ligament meets the two side ligaments at the bottom, making a strong sling.
|17 The udder has
the two quarters on the left are clearly divided
from the two quarters on the right.
|18 It is possible for a cow to have disease in one quarter without affecting the other quarters.|
|19 The front and rear quarters of the udder are
not clearly separated.
The rear quarters are larger and produce about 60% of the milk.
|20 Each quarter usually has one teat and the
rear teats are usually shorter than the fore teats.
|21 The teat has:
- an opening for milk to come out
- a lining to protect against bacteria.
|22 Signs of good teats are:
- moderate size
- good position in quarter
- good muscle tension to stop leaks but allow easy milking.
|23 Consult your extension worker about calves
with more than 4 teats.
Removal of extra teats helps protect against mastitis.
|Inside the udder
24 Inside the udder you can see lobes which produce milk.
The milk from each lobe passes through large ducts to the gland cistern which can store about 1/2 l milk.
Folds in the tissue help to keep the milk in the gland cistern until the cow is suckled or milked.
The teat is hollow and can hold a small amount of milk.
The streak canal (about 1 cm long) is at the end of the teat and leads to the outer opening.
The canal is involuntarily closed between milkings.
lobe has a number
of lobules and one large duct which drains the milk.
Connective tissue separates the lobules.
|26 Each lobule has many alveoli and a duct which drains the milk from the lobule into the lobe duct.|
|27 Through a microscope, you can see that each alveolus has a small duct which drains milk into the lobule duct.|
|28 The alveolus is like a small sac.
The cells on the wall secrete particles of milk fat covered in protein into the hollow centre of the alveolus.
|29 The mammary ducts
drain the milk from the lobes into the gland cistern.
These ducts only store and drain milk.
|30 The streak canal secretes a liquid
which fights bacteria.
A muscle closes the streak canal.
If the muscle is loose, milking is faster but it is easier for the cow to get udder infections.
|The blood system
31 Arteries carry blood from the heart to the udder and carry food and oxygen.
Veins carry blood with waste products away from the udder.
|32 Looking from the back, you can see the milk
veins and other veins and the middle ligament.
33 Blood flow is important for milk production.
About 500 l of blood must flow through the udder to produce 1 l of milk.
|34 The nerve and the
Other nerves send messages from the udder and other parts of the body to the brain about touch, temperature and pain. The body then releases hormones which also control blood flow and milk production.
|35 Touching and washing the udder
sends a message to the brain and glands release a hormone oxytocin
into the blood.
This helps milk let-down.
|36 Excitement and pain also send messages to
Glands release another hormone epinephrine which reduces blood flow and milk production.
Lymph ducts drain colourless fluid from tissues into the blood vessels.
| 38 You can feel some of the lymph nodes
through the skin.
They are part of the cow's immune system and help fight disease.
|39 Near parturition, the lymph ducts cannot
drain enough fluid from the udder which swells more than normal.
This is called udder edema.
|40 Milking does not help because the fluid is between the cells and not in the milk ducts.|
|41 Reducing salt intake may help because
salt keeps water in the cow's body.
If the swelling is bad, call your vet who can give drugs.
|42 Each alveolus has cells which produce the substances in milk e.g. sugar, fat and protein.|
|43 Each cell in the alveolus has many structures
To produce milk the cell:
-takes nutrients from the blood
-produces the milk substances inside the cell
-releases milk substances into the alveolus where they mix with water to form milk.
49 Under feeding and over feeding lead to poor milk production.
Time after calving
Time after milking
Number of milkings
- you have to give more feed
- you have to do more work.
56 If your cow is hot, she will eat less and produce less milk.
|57 Keep your cow cool with:
- insulated roof
- fan or breeze
|58 Gentle exercise helps
|59 but make sure your cow is quiet and calm around milking time.|
Call your vet.