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Dairy Farming Manual

Volume 4

Husbandry Unit 6.1

page 1

Extension Materials


What is A.I. and why use it? (5-20)

1 A.I.:
- passes semen from a bull to a cow without direct contact
- helps you get more calves from good bulls.

How does your cow show heat and how do the female reproductive organs work? (21-46)

2 You should know:
- all the heat signs
- the names of the reproductive organs
- what the reproductive organs do.

How does the A.I. technician inseminate your cow? (47-56)

3 He prepares the semen and uses a breeding gun to inseminate your cow.

How often should your dairy cow calve and are there any differences for buffalo? (57-69)

4 Dairy cattle should calve every 365 days.

Buffalo should calve every 425 days.


  page 3

 What is A.I.?  (5-8)

A.I. stands for "Artificial Insemination".  A.I. is different from natural mating.  In A.I. semen is collected artificially and deposited in the uterus of the cow.  A.I. is widespread and used in many countries, especially for breeding dairy cattle.

page 4
5 In natural mating a bull mounts a cow and ejaculates his semen into her vagina.
6 In artificial insemination (A.I.) the A.I. technician collects semen from a bull in a bag called an artificial vagina.
7 He keeps the semen frozen in a special container until you need it for your cow.
8 When the cow is in heat, the A.I. technician inseminates the cow with a breeding gun (insemination rod).


  page 5

 Why Use A.I.?

Important reasons for using A.I. are:

- No direct contact between bull and cow.  This reduces the risk of transfer of disease and of injuries from natural mating.  (9)

- One portion of semen (ejaculate) from one bull can be divided into enough doses to inseminate 200-250 cows.  In natural mating, one bull can serve only about 30 cows per year.  A.I. transfers the genes from a good bull to a large number of offspring and breed improvement takes place much more quickly than in natural mating.  (10-12)

page 6

9 Artificial insemination of dairy buffalo and cattle has many advantages:

No direct contact between bull and cow.

This means:
- less disease transferred
- fewer injuries from mating.

10 Semen from one bull can be used for inseminating many cows.

This means:
- more calves from good bulls.

11 You can take semen from a bull in one place
12 and transport it to cows in other places.


  page 7

 3.  A.I. technicians use semen from different bulls even in small herds.  This allows the farmer to choose his own breeding policy. (13)

4.  Depending on local conditions, A.I. costs may be lower than the costs of keeping a herd bull.  (14-15)

page 8

13 Even in small herds, you can use semen from different bulls.

This means:
- you can produce the crossbreeds you want.


Natural breeding
14 It is expensive to keep a herd bull.

Artificial insemination
15 A.I. may be cheaper than keeping a herd bull.
 page 9

 The use of A.I. for riverine (e.g. Nili-Ravi) and swamp buffalo is limited for two main reasons:

 1. A.I. is not available.

 2. Faulty techniques for A.I.

page 10

16 As well as dairy cattle, A.I. is suitable for both Swamp buffalo


17 and River buffalo.

If you have difficulty:
- consult your A.I. worker
- make sure he is qualified.

  page 11

 Disadvantages of A.I.

- The A.I. system will only work well if the management of the farms is efficient, in particular the farmers' ability to perform heat observation.  (18)

- The regular use of A.I. in a certain area requires a well organized A.I. system with continuous recording and monitoring and well trained A.I. personnel (inseminators).

- Semen may transfer undesired heritable traits and infectious diseases.  The A.I. technician must use only checked semen taken from a bull which has been tested not to transfer undesired traits and not to carry and diseases transferable by semen.  (20)

page 12

Things to remember in A.I.
Make sure:
- you are able and ready to observe signs of heat in your cow


- you can call the A.I. technician quickly when your cow shows signs of heat
- you use an A.I. technician who is well trained.
 page 13

 Heat observation

A non-pregnant cow with a normal oestrus cycle will release an egg and show heat about every 21 days (variation: 18-24 days).

The typical signs of heat are:

1. Restlessness, the cow separates from other cows when it is walking in the field.  (21)

2. Some breeds bellow to attract the bull.  Zebu (=native) cattle, however, normally do not bellow.  (22-23)

3. Milk production and food intake may decrease.  (24)

page 14

21 About every 21 days non-pregnant cows are ready for breeding.

They show signs of heat.
The heat period lasts about 18-20 hours.
Signs of heat include restlessness and separation from other grazing cows.

22 The cows of some breeds of dairy buffalo and cattle bellow to attract the bull.
23 Some cows of certain breeds of dairy cattle (e.g. Zebu) and dairy buffalo (e.g. Nili-Ravi) do not bellow.

They have silent heat.

24 Food intake and milk production may decrease.


  page 15

4. The cow tries to mount other animals, sniffs at others, and other cows sniff at the cow in heat.  (25-26)

5. Other cows try to mount the animal in heat and she stands and allows them to do so:  standing heat.  (25-26)

6. The lips of the vulva become red and swollen.  (27)

7. A thin, clear discharge from the vulva opening can be seen, sometimes sticking to the tail and skin surroundings.  (27)

8. By rectal palpation increased uterus tonus can be felt.

Extra care in heat observation needs to be taken with buffalo cows.  Many of them: (28-9)

- Show very poor signs of heat and may have silent heat.

- Come on heat late at night when the signs are more difficult to detect.

page 16

25 The cow in heat tries to mount other cows.

The cow in heat allows other cows to mount her.

This is called standing heat and is important to notice.

26 Other cows sniff the cow in heat.
27 The lips of the vulva become red and swollen.

You may see a thin sticky clear discharge like egg white.

This runs from the vulva and may stick to the tail and skin.

 page 17

28 Buffalo cows often show poor signs of heat and have silent heat.

You must observe carefully.

29 Buffalo often show signs of heat late at night.

You should check them at this time.

page 18

 Normally, the farmer will not see all signs of heat at the same time.  Some signs of heat may be absent or too weak to be observed.  (31)

The standing heat period normally lasts 18-20 hours, but may be several hours shorter or longer.  (33)

For the inseminator it is important not only to question the farmer about previous inseminations, treatments and proper heat signs but also to check by himself that the cow to be inseminated:

1. Really is in heat: insemination of cows not in heat easily causes infection of the uterus (metritis, pyometra).

2. Has no reproductive disease (especially uterus infection), in which case insemination is not likely to succeed.

3. Is not pregnant already: insemination of pregnant cows results in abortion.

Timing of insemination

The best possibility for getting a cow pregnant is when insemination is done in the last half of the standing heat period or within 6-8 hours after the end of the standing heat period. (33-38)

page 19

30 The heat period is short.

Be ready to observe:
- early morning before milking
- afternoon before milking
- before going to bed.

31 You may not see some heat signs at all.
32 Look out for the typical discharge and for standing heat.

Your cow is in heat. When do you inseminate?

33 Inseminate the cow towards the end of the heat period or at latest within 6 hours of the end of the heat period.


page 20

The normal working routine to follow is:

1. If the farmer observes heat early in the morning, inseminate in the afternoon of the same day.  (34)

2. If the farmer observes heat in the afternoon, inseminate early next morning.   (35)

page 21

34 Heat signs early in the morning.

Inseminate in the afternoon - same day.

35 Heat signs in the afternoon.

Inseminate in the morning - next day.

36 Look carefully for signs of heat.
37 Inform the A.I. technician quickly, within 3-5 hours of observing heat.


page 22

Fertilization, that is the combining of egg and sperm, takes place when the egg reaches the egg duct.  If the A.I. technician performs the insemination too early, the sperm deposited in the cow dies before the egg reaches the egg duct.  If he performs the insemination too late, the egg dies before the sperm is deposited.  Therefore, neither too early and too late inseminations will result in pregnancy.  (38)
page 23


Inseminate at the right time:
at end of the heat period
- your cow should get pregnant

Too early                   or                      too late
- your cow will not get pregnant

page 24

 How do A.I. Technicians collect, process and handle semen?

A.I. technicians collect semen only from tested sires, normally by using an artificial vagina. (39-42)

They clean and sterilize the artificial vagina every time it is used and store it in a clean and dustfree place.  When in use, A.I. technicians keep the inner wall of the artificial vagina at 40-45 C.

The bull mounts a "teaser" animal or a "dummy", and ejaculates into the artificial vagina held by the A.I. technician who collects the semen in a vial.  After collection, he judges the quality of the semen by looking at semen volume, colour, consistency, mass motility (that is: overall movement observed in the microscopy, "waves"), individual motility of sperm cells and semen morphology (that is: normal/abnormal looking cells).  (41)

A.I. technicians use only semen of good quality for further processing.  This includes freezing in liquid nitrogen at -196 C in straws, marked for identification.  They check the semen for quality again before distributing to the field.
  page 25

How good is semen in A.I.?

Is the semen clean?
Yes, the semen is collected in an artificial vagina which is clean and free from germs

Is the semen free of disease and of good quality?
Yes, it is carefully tested for quality and taken only from healthy animals

Is the semen still good after storage and transportation?
Yes, it is frozen and stored at - 196 C and kept in special containers

 In the A.I. centres, they keep the semen frozen in liquid nitrogen containers at -196 C.

The A.I. technicians must keep the straws under the liquid level and must not lift them up into open air for checking number and colour, the temperature change will immediately destroy the semen cells.

The inseminator transfers the straws as quickly as possible to a small liquid nitrogen container which he takes to the field.  He uses long tweezers to reduce the time of transfer outside the nitrogen tank further.

page 26

 The female reproductive organs of dairy buffalo and cattle

The illustrations below show the anatomy of the female reproductive organs of dairy buffalo and cattle.

Hormones from the brain, the ovaries and uterus control the growth and release of eggs from the ovaries.

After release, the infundibulum or "trumpet" catches the egg and then it reaches the egg duct (oviduct).  In mating or A.I.,  fertilization with a sperm cell takes place here.  The fertilized egg moves to the uterus horn where it attaches to the wall and develops into a fetus.

Correct A.I. technique deposits the semen in the uterine body, not in one of the horns.

page 27

How do the female reproductive organs of dairy buffalo and cattle work?

Reproductive organs:
1. Ovary produces eggs 
2. Trumpet of egg duct catches the egg from the ovary 
3. Egg duct between trumpet and uterus, transports the egg 
4. Uterus hollow organ with horns, carries fetus in pregnancy 
5. Neck of uterus connects with vagina 
6. Vagina passage for semen, urine and birth 
7. Vulva outer opening of reproductive system. 

page 28

 The insemination procedure

Introduce the breeding gun (insemination rod) into the vagina.  The plastic sheet over the breeding gun is sterile.  Keep it as clean as possible during the insemination procedure.

One way to do this is as follows:  introduce the left arm into the rectum and exert a moderate pressure downwards to open the vulva.  When the mucosa becomes visible, introduce the breeding gun without touching the skin.  (52-53)

Introduce the breeding gun further along the upper wall of the vagina to avoid introduction into the blind saccule in front of the urethra or into the urinary bladder.

At this stage, check for possible non-heat, abnormal conditions or pregnancy by rectal palpation with the left hand.

If insemination is continued, press the vaginal part of the cervix forwards with forefinger, thumb and middle finger.  Introduce the breeding gun to contact the fingers at the same time.

Breeding gun in position in front of the cervix
page 29

Preparing the semen
44 The A.I. technician freezes the semen and keeps it in straws in the special container.
45 He removes a straw and thaws it in water immediately before use.
46 The straw is sealed at both ends.

One straw contains 20 - 30 million sperms.

47 He places the 

straw inside the breeding gun.

semen inside the straw


The semen comes out 

when he pushes the piston.


page 30

Breeding gun in position in front of cervix

5. When the tip of the breeding gun is in position outside the cervix opening, gently try to push the breeding gun through the cervix, without using force.

   Breeding gun in position                        Breeding gun passing
in front of cervix opening                              through cervix

6. With the tip of the forefinger you can feel when the tip of the breeding gun passes through the cervix into the uterus body.  This is the correct place of deposit.

 Correct deposit of semen before the breeding gun reaches one of the horns

Important things to remember:

1. Always work as cleanly as possible.  If you introduce any dirt into the uterus, it may cause infection, especially if the cow is not in heat.

2. Always check the cow for abnormal conditions such as abnormal discharge, different size of the two uterine horns, possible pregnancy or missing heat.  If in doubt about  insemination, wait and check later or ask a veterinarian to check.

3. Follow a sensible routine when you inseminate.  This makes the work quicker and ensures that you always use a hygienic procedure.

page 31

48 The farmer should stand beside the cow.
This keeps the cow calm.
The A.I. technician stands behind.
49 The A.I. technician puts one arm into the gut (rectum) of the cow.
He fixes the neck of the uterus through the wall of the gut.
50 The other arm introduces the breeding gun through the vulva, vagina and the neck of the uterus.

When the breeding gun is in the right place, the A.I. technician pushes the piston and the semen enters the uterus.

page 32

 Pregnancy diagnosis

Sometimes the farmer does not know that his cow is pregnant and asks for insemination of a pregnant animal.  Some cows may also show signs of heat even though they are pregnant already.

At the examination before A.I., it is possible for the inseminator to diagnose a possible pregnancy from day 60 after conception.  A number of conditions indicate pregnancy, the most significant are as follows:

- Different size of the uterine horns.  This may be due to pregnancy, but may also come from inflammation or previous calving.

- Fluid content in one or both horns (may also be due to inflammation).

- Slip of fetal membranes when the inseminator lifts up the uterus wall.

- Palpation of placentomes, the size is about 1-2 cm diameter at 3 months pregnancy up to about 8 cm at 8 months pregnancy.

- From about 70 days after conception the inseminator can feel (part of) the fetus.  Beware that the fetus may be out of reach at about 5-6 months pregnancy where it "drops" down on the abdominal wall.

- From about 90 days after conception, the inseminator can feel the increased size and pulsation of the middle uterine artery at the pelvic wall.  The size of the artery is about 4-5 mm diameter in early pregnancy, becoming increasingly larger later in pregnancy.

If there is any doubt that the cow is pregnant, do not inseminate but wait and examine at a later stage.

page 33

51 After A.I. observe carefully for signs of heat.
No signs of heat 21 days after A.I. means that your cow may be pregnant.
52 60 days after A.I., if there are no signs of heat, call the A.I. technician or veterinarian to check for pregnancy.
53 If there are signs of heat and the cow is not pregnant, repeat A.I.
page 34

How often should your cow calve? (Dairy cattle)

54 Your cow should calve every 365 days to give the best milk production for your farm.

           Birth          First heat seen       Second heat        Third heat      Dry period

If your cow does not calve every 365 days:
- you will have fewer calves
- you will have fewer dairy cows
- you will have less milk.

page 35

 What to do about reproductive disorders

 Repeat breeding

 Some cows fail to come on heat, show signs of heat irregularly or do not become pregnant after insemination (repeat breeders).  The reasons for this may be many and can depend on the cow (abnormal body function) as well as the management (for instance:  wrong feeding, failure of the farmer to observe heat).  After 3 inseminations not resulting in pregnancy, ask the veterinarian to investigate causes of infertility.

 Infectious diseases

 Abnormal vulva discharge, repeat breeding, abortion, retained placenta, dystocia and still born or abnormal calves may all be signs of infectious disease.  Other animals can get these diseases.  If any of the above signs are present, isolate the sick cow from the rest of the herd and call the veterinarian at once.  Man can catch some reproductive diseases (for instance: Brucellosis) and become seriously ill.


 Metritis is infection of the uterus and not uncommon after calving, especially with dystocia or retained placenta.  Metritis may also be present after A.I. or mating.  There is sometimes, but not always vaginal discharge.  Other signs include reduced food intake, fever, general bad condition.  The veterinarian can treat metritis and early treatment helps full recovery.

page 36

58 You may be doing something wrong.
- reproductive disorders
- feeding and management
- heat observation.
59 There may be something wrong with your animal.
Inform the veterinarian if your cow is not pregnant after 3 inseminations.
60 Separate your animal from the others and inform the veterinarian immediately if your cow shows signs of disease:
- abnormal vulva or nasal discharge
- abortion
- retained placenta
- still born calves
- fever
- blood in urine
- ropy milk
- poor appetite.
page 37

 Heat signs in buffalo  (61)

In India, it has been observed that the manifestation of heat in buffaloes is weak and the heat is of shorter duration during summer.  This necessitates close observation for different signs of heat at shorter intervals.  It has further been observed that teaser bulls had poor libido during summer.  For efficient heat detection, therefore, protection against climatic stress should be provided.

It has been observed that few buffaloes exhibit signs of oestrus from 10 a.m. to 5 p.m.  Most activity occurs near sun rise and sun set.  Hence the breeding time is either missed during the night or breeding services at that hour are not available.

Late sexual maturity  (62-63)

Puberty refers to the state of the animal when she is physically fit for reproduction as indicated by regular exhibition of the oestrus cycle.

Sexual maturity has immense economic importance for successful buffalo dairy farming.  Economically, early first calving will ensure smaller investment and quicker return of the capital.  Genetically, it reduces the generation interval, resulting in larger annual genetic gain from selection.

The skeletal parts grow more rapidly after birth than other tissues.  This rapid rate of skeletal growth decreases by about six months.  Maximum muscular development occurs thereafter.  The maximum growth rate is between 3 and 6 months and falls steeply after one year of age.

The young females when one year old are generally kept together with elder heifers and as such fail to get their share of nutrients.  The problem appears to be one of management.  On average, the age at first heat has been reported to be 30 months (range 26-62 months).

It has been indicated that the occurrence of first heat is more a function of weight than age.  Most buffaloes generally start exhibiting heat symptoms on attaining about 340 kg body weight.  Hence breeding, feeding and management practices should be directed towards attaining this weight as early as possible.

Buffaloes heifers fed normal rations but under intensive management alone could calve at 36 months of age.

page 38

58 In buffalo, signs of heat:
- are often weak
- are often short, especially during summer
- often occur at night.
You must observe carefully.
59 The first heat in buffalo depends more on weight than on age and usually occurs about 340 kg body weight.
60 You should breed, feed and manage your buffaloes so they get to this weight as soon as possible.
page 39

What are the main differences between dairy buffalo and cattle?

 Breeding behaviour  (64-66)

 Dairy farmers suffer economic losses due to low reproductive efficiency in seasons of high environmental temperature.  Seasonality of calving in buffaloes has been much debated in the past.  However, it is now quite well known that buffaloes breed and calve throughout the year but certain months and seasons are more favourable for breeding than others.  Data regarding frequency distribution of oestruses and calving in Pakistan buffalo show that about 63 percent of the buffaloes came in oestrus during autumn (September to November) and winter (November to February).  The distribution of calvings indicate that although the buffaloes calved throughout the year, the maximum calvings (39%) occurred  during the humid - hot (July to September) season followed by 26% calvings during autumn (September to November).  Spring calvers are very infrequent.

 From the analysis of data on Nili-Ravi buffaloes in Pakistan under farming conditions, it was revealed that when teaser bulls were allowed access to buffaloes throughout the year, the frequency of calvings improved.  The sexual activity of the males, during May and June was minimum, the temperature was highest and buffalo often failed to come on heat.  The animals started coming on heat from July to September (humid - hot season) and reached a peak during autumn when the day length was decreasing.

 In another study it was observed that of all calvings, 60 percent occurred from July to October.  It was concluded that calvings in this period were followed by 40 days earlier return to oestrus, 48 fewer days open (service period) and 47 days shorter calving interval than for calvings in other months.

page 41

61 Buffaloes are very seasonal animals.

Mid September to end November is the active breeding period.

This is the best time for breeding.

62 This shows the active calving period.

The highest number of calvings is the period from July to September.

page 42

How often should your cow calve? (Dairy buffalo)

63 Your cow should calve every 425 days to give the best milk production for your farm.

                Birth      First heat seen    Second heat    Third heat      Dry period

If your cow does not calve every 425 days:

You should begin breeding at 45-60 days after calving to make the calving interval as short as possible.

page 43

65 To keep your cow healthy and calving every year you need to record information to answer the questions of the A.I. technician and veterinarian.
66 Keep records on a special card for each cow.

Write down important things about your cow. Then it is easy to remember.

67 Keep records about:
- dates
- what happened: calving, vaccination, A.I., health etc
- the exact figures
- anything special.
Discuss the cow card with your A.I. technician or veterinarian.
page 44

ANIMAL:      Ear tag no: __________ Breed: __________ Birth date: __________
OWNER:       Farm no: ____________ Name: __________ Address: ____________
1st  Insemination (A.I.)
Heat  A.I.   No Bull 
Date Date
2nd Insemination (A.I)
Heat   A.I.    No Bull
Date   Date
3rd Insemination (A.I)
Heat    A.I.     No Bull
Date    Date
Pregnancy Diagnosis Date Remarks
Year Calving No Calving Date Sex Calf Father Birth Weight Aid required at calving
page 45

What do you know about A.I.?
    A.I. and reasons for using it
    1 Differences between A.I. and natural mating 
    2 Reasons for using A.I.
        - no direct contact between bull and cow 
        - can use semen from good bulls in other places 
        - A.I. may be cheaper than a herd bull 
        - A.I. suitable for dairy cattle, swamp and river buffalo 
    Things to remember in A.I.
    1 Be ready to observe heat signs, day or night 
    2 Call A.I. technician when heat signs observed 
    3 Use only well-trained A.I. technician 
    Heat signs
    1 Restlessness and separation 
    2 Bellowing 
    3 Lower food intake and milk production 
    4 Sniffing and mounting other cows and being mounted 
    5 Discharge from vulva 
    6 Heat signs in buffalo
    7 Important points in observing heat 
    When to inseminate
    Within 6 hours of the end of the heat period 
    Quality of semen
    1 Semen is carefully selected to be: 
       - clean
       - free of germs
       - free of disease
    2 Semen kept in good condition by freezing at -196o
    The function of the reproductive organs
    Names of 7 major reproductive organs and their functions
     1 Preparing semen:
    - collecting 
    - testing 
    - freezing and storage
    - thawing 
    - placing in breeding gun 
    2 Inseminating the cow:
    - position and keeping cow calm 
    - introducing breeding gun 
    - depositing semen 
    3 Checking pregnancy after insemination:
    - no heat signs 21 days after A.I.
    - pregnancy possible 
    - no heat signs 60 days after A.I.
    - call vet. to check 
    - heat signs and cow not pregnant:
    - repeat A.I. 
    Frequency of calving for dairy cattle 
    Reasons for cows not calving every year
    1 Poor management or heat observation 
    2 Problem with cow   
    Isolate if signs of disease and inform vet  
    Main differences between dairy cattle and buffalo
    1 Weak heat signs in buffalo 
    2 Importance of weight in buffalo 
    3 Breeding behaviour
    Frequency of calving for dairy buffalo
    Record keeping
    1 Reasons for record keeping 
    2 What to keep records about 
    3 Cow card for breeding and calving 

page 47

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