Small-ScaleDairy Farming Manual |
Volume 4 |
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Why is knowing about the physiology of milk
production important? (5-8)
1 So you can improve your:
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What is your cow's udder like? (9-41)
2 The udder is a skin gland with four quarters and teats. |
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Where does your milk come from?(42-46)
3 Cells in the udder take nutrients from the blood and produce milk substances. |
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What affects milk production? (47-60)
4 Many factors in:
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5 Breeding affects milk production |
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6 but so do your feeding and management. |
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7 Knowing about the physiology of milk production helps you to improve your feeding and management |
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8 and to produce more high
quality milk and increase your income.
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9 The udder is a well developed skin gland. |
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10 It is like sweat glands and tear glands which also secrete fluids to the outside of the body (exogenous glands). |
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11 All female mammals have an udder for feeding their young |
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12 and your cow's long lactation period gives
milk for you as well as her calf.
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Outside the udder
13 The udder weighs between 10-30 kg without milk. Signs of a good udder are:
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14 The skin covers the
udder and protects it from rubbing and from bacteria.
But it is not strong enough to support the udder. |
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15 Strong tissues called ligaments
help to suspend the udder.
Two bands run along each side of the udder. |
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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.
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17 The udder has
4 quarters
and
the two quarters on the left are clearly divided from the two quarters on the right.
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18 It is possible for a cow to have disease in one quarter without affecting the other quarters. |
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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. |
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20 Each quarter usually has one teat and the
rear teats are usually shorter than the fore teats.
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21 The teat has:
- an opening for milk to come out
- a lining to protect against bacteria.
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22 Signs of good teats are:
- moderate size - good position in quarter - good muscle tension to stop leaks but allow easy milking. |
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23 Consult your extension worker about calves
with more than 4 teats.
Removal of extra teats helps protect against mastitis. |
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25 Each
lobe has a number
of lobules and one large duct which drains the milk.
Connective tissue separates the lobules. |
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26 Each lobule has many alveoli and a duct which drains the milk from the lobule into the lobe duct. |
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27 Through a microscope, you can see that each alveolus has a small duct which drains milk into the lobule duct. |
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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.
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29 The mammary ducts
drain the milk from the lobes into the gland cistern.
These ducts only store and drain milk.
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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. |
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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. |
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32 Looking from the back, you can see the milk
veins and other veins and the middle ligament.
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33 Blood flow is important for milk production. About 500 l of blood must flow through the udder to produce 1 l of milk. |
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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. |
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36 Excitement and pain also send messages to
the brain.
Glands release another hormone epinephrine which reduces blood flow and milk production. |
Lymph ducts drain colourless fluid from tissues into the blood vessels. |
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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. |
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39 Near parturition, the lymph ducts cannot
drain enough fluid from the udder which swells more than normal.
This is called udder edema. |
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40 Milking does not help because the fluid is between the cells and not in the milk ducts. |
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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.
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42 Each alveolus has cells which produce the substances in milk e.g. sugar, fat and protein. |
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43 Each cell in the alveolus has many structures
inside it.
To produce milk the cell: |
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-takes nutrients from the blood |
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-produces the milk substances inside the cell
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46 -releases milk substances into the alveolus where they mix with water to form milk. |
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Heredity
47 Different breeds and different cows can produce different amounts of milk. |
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Nutrition
48 Your cow needs the right amounts of feed, roughage and concentrates for maintenance and production rations. |
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49 Under feeding and over feeding lead to poor milk production.
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Time after calving
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Dry period
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Age
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Body size
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Time after milking
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Number of milkings
 - you have to give more feed - you have to do more work. |
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Temperature
56 If your cow is hot, she will eat less and produce less milk. |
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57 Keep your cow cool with:
- insulated roof - shade - fan or breeze - shower. |
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58 Gentle exercise helps
milk production
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59 but make sure your cow is quiet and calm around milking time. |
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Disease
60 If your cow has mastitis, milk fever or other disease, the quantity and the quality of your milk is lower. Call your vet. |
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