AI- TIMING & TECHNIQUES FOR MAXIMUM CONCEPTION IN DAIRY CATTLE
A frequent question concerning AI is: What time during estrus should cows be bred for greatest chance of conception? Since estrus may last from 10 to 25 hours there is considerable latitude in possible time of insemination. Much research work has been conducted on this subject. The studies show that conception rate is lower when cows are bred prior to mid estrus or later than 6 hours after cessation of estrus (standing heat in this case).
Maximal conception is obtained when cows are inseminated between mid-estrus and the end of standing estrus, with good results up to 6 hours after estrus. Success in insemination timing is dependent upon a good heat detection program. In large herds, this means assigning individual responsibility for heat detection and a continued education program for labor. A successful heat detection program and subsequent proper timing of insemination will pay dividends in increasing reproductive efficiency.
A practical recommendation for timing of insemination
Cows showing estrus Should be inseminated Tool late for good results
In morning Same day Next day
In afternoon Morning of next day or early afternoon After 3 p.m.
Time of Insemination
The heat cycle has three distinct phases.
- Pre-heat – lasts 4-6 hours. The cow bellows, is restless, milk production may be down, she will mount other cows but not stand to be mounted herself. The vulva may appear moist and red and she may show beginning signs of a bull-string. She may sniff the vulva area of other cows.
- Standing heat – lasts 6 – 30 hours, average for heifers and indigenous breeds 12 hours, cows 18 hours. The vulva is obviously swollen and red and there may be a bull-string. The cow is very restless, frequently bellowing. She will stand to allow other cows to mount her. The time to note is the beginning of this stage – ie the first time the cow is seen standing firm and allowing others to mount her. Maximum conception rate is achieved when AI occurs 12 hours after first standing heat.
- End of heat – although the cow is still restless and may attempt to sniff and mount others, she will no longer stand to be mounted. At this time she is ovulating and AI may be too late for best results. Occasionally a show of blood may be seen at the vulva, this does not mean that the cow is pregnant.
Proper Timing of Insemination for Maximum Conception
Females go into heat once every 21 days. Conception rate is lower when animal are bred prior to mid estrus. Maximal conception is obtained when cows are inseminated between mid estrus and the end of standing estrus. This time period is when the female ovulates, sending an ovum out to the fallopian tube to await fertilization from sperm from a bull. In cows estrus may last from 10 to 24 hours and in buffalo estrus lasts from 6 to 12 hours. Success in insemination timing is depends upon a good heat detection. In field heat detection is responsibility of farmer. A successful heat detection and subsequent proper timing of insemination will increase reproductive efficiency. Practical recommendation for timing of insemination are:
Buffalo showing estrus Should be inseminated
In Morning Same Day Evening
In Evening Next Day Morning
Cows showing estrus Should be inseminated
In Morning Next day Morning
In Evening Next day afternoon
Steps for doing A.I
The following steps should be followed while doing A.I. Please also consider using an experienced certified AI technician to AI your animal. These people are better to use than training yourself to do it.
• Watch your animal for signs of estrus as discussed earlier. Physiological, behavioural and physical signs of heat which last for 24-36 hours. Most heat periods start or end around dusk or dawn.
• Handle the animal in calm way with proper handling practices, without irritating animal.
• If doing AI outside, it is best to do it on sunny warm days, not when the weather is rainy or windy or even stormy. If you have a facility that is set up inside a shed or barn, so much the better.
Preparations Prior to Insemination
- Prepare a water bath that is between 90 to 95 degrees Fahrenheit (or 34 to 35 degrees Celsius) in a thermos. Use a thermometer for better accuracy.
- Identify which canister contains the semen you need.
- Remove the canister from its storage location to the centre of the tank. Lift the canister just high enough into the neck region of the tank to grasp the desired cane of semen. Keep the tops of the canister or canes no higher than the frost line, or two to three inches from the top of the tank.
- Grasp the desired cane then immediately lower the canister to the tank floor. Keep the cane as low inside the tank as possible while removing the straw of semen with tweezers. Never take semen straw with bare hand. You only have 10 seconds to take the semen straws out.
- Shake the straw to remove excess liquid nitrogen (nitrogen quickly goes into a gaseous state when exposed to air and warmer temperatures) otherwise it can burst the semen straw when put in water bath.
- Immediately place it the prepared thermos of water and keep it in there for 40 to 45 seconds. This process is known as thawing.
- Get your AI gun ready by having it pre-assembled (this should be done before/after you prep the thermos with warm water. If it’s cold outside, warm the tip. Rubbing a paper towel on the rod also helps warm it up. If it’s hot outside, keep it in a cool place. The AI gun should not be extremely hot or cold to the touch.
- Remove the straw from the thermos and wipe it dry with a paper towel. It should be completely dry before you do anything else with it. The flick should move the bubble to the end you are holding.
- Put the straw in the rod. Use sharp scissors or specially designed straw-cutter scissors should be used, and cut in the area that the air bubble is located.
- Wrap the AI gun in a clean dry paper towel or protective sheath and tuck it in your clothing close to your body to both transport it to the animal and to maintain a constant temperature.
- Artificially Inseminating the Female Bovine. Move the tail so it’s on top of your left forearm or tie it up so it will not interfere with the AI process. Raise the tail with one hand (preferably the right) and with the other (which should be gloved and lubricated), gently reach inside the cow to clean out any faeces that may interfere with the process of feeling for and inserting the AI gun into the animal’s vagina. Clean the vulva with a clean paper towel or rag to remove excess manure and debris.
- Take the gun out of your jacket or overalls, unwrap it, then insert it at a 30 degree angle into the cow’s vulva. This is so that you avoid going into the urethral opening into the bladder.
- With your left hand in the rectum of the cow (which should have been there to begin with), feel with your finger tips through the wall of the rectum and vagina the location of the end of the AI gun until you reach the cervix.
- Grasp the cervix with the hand in the rectum of the cow (like you would hold a bar that is below your hand) and hold it steady while you thread the rod into and through the cow’s cervix.
- When the rod is all the way through the cervix, check the location with your index finger. The rod should be only 1/2 to 1/4 of an inch into the uterus.
- Slowly depress the plunger at the end where your right hand is so that 1/2 or is deposited.
- Recheck the location of the semen to make sure you are in the cow’s uterus and not in any of her “blind spots” (see tips below), and deposit the other half of the straw’s contents.
- Slowly remove the AI gun, your hand and arm from inside the cow. Check for any blood, infection or semen “feedback” from inside the sheath.
- Recheck the straw to see if you used the right bull semen for the cow.
- Dispose the straw, glove, and towels in the proper place.
- Clean the AI gun if necessary.
- Record breeding information on any record keeping system you have on hand.
Points to keep in mind while inseminating
• Semen Straw should not come in contact with water or scissors while cutting the tip of straw, as water changes ph of semen.
• Inseminating equipment should avoid contact with lubricants at all time, because most lubes are spermicidal.
• Take your time while breeding of animal. Never be in hurry while inseminating the animal as rushing around causes far more mistakes than taking things calmly and slowly.
• Liquid nitrogen is the best solution to use to keep semen cold and keep them for a long time.
• Always keep inseminating equipment clean, warm and dry.
• Never let the end of the AI gun goes very far past the cervix, otherwise infection or puncture of the uterine wall may occur.
• Always keep the end of the pipette UP at a 30 degree angle, not down, to avoid going into the bladder.
• Use your fingers to help move and locate the AI gun down the animal’s vagina. Avoid two particular blind spots as you get closer to the cow’s cervix.
• There is a blind circular pouch that joins to the backward-facing cervix. This pocket surrounds the entire dome-shaped rear of the cervix
• The cervix also is not a straight-and-narrow passage way. It contains finger-like projections that cause the passageway to be crooked. They also cause dead-ends or blind pockets that can cause problems animal.
Artificial Insemination (AI) allows rapid genetic progress and removes the stresses of having to keep bulls. With good management practices and well trained inseminators and staff conception rates should equal those achieved by the bull. For successful breeding of both the beef and the dairy herd, there are however, management techniques to ensure maximum conception rates.
Advantages of AI
• Faster genetic progress
• No spread of venereal disease
• The farmer chooses when his cows become pregnant
• The farmer can select bulls for the traits wanted in the herd
• It is cheaper to buy semen than to keep a bull and much less stressful ! To ensure best results
• Purchase semen from a reliable renowned source to ensure you are not introducing undesirable traits into the herd
• Heat detectors must be well trained and understand the importance of good accurate detection. Early reporting of cows on heat.
• Management and level of nutrition of the female animals must be excellent. Cows and heifers must be on a rising plane of nutrition for maximum conception and have a Body Condition Score of 2.5 minimum.
• AI requires training and refresher courses for the inseminators
• Timing of insemination is essential. (See Best Time to Breed Chart)
• Good semen handling practices to ensure maximum life of the sperm
• AI technique and placement of semen on the uterus (slow withdrawal of the pipette, semen placed in the body of the uterus, calm quiet environment and hygiene practices.)
• Accurate record keeping of calving dates, dates of first service, dates served and by whom, to which bull, and PD results.
• Bulls must be controlled, preferably culled or castrated, but if kept must be well penned far from the cows that are cycling. Guidelines for Heat Detection (See Best Time to Breed Chart) The cow’s normal oestrus cycle is 18 – 24 days depending on breed. Heifers have a shorter cycle, about 19 days and indigenous breeds also have a shorter cycle and often cycle at night, for a shorter time. Heat can last from 12 – 30 hours; heifers, young cows and indigenous breeds can have a very short heat period. It is important to time the heat detection so that these ‘shy cyclers’ can be detected and served.
• Time of day – early morning and evening are the best times to detect for heat. This is the time when dairy cows are being brought in for milking and beef cows are being taken to and from grazing or being fed, so it is a convenient time to spend with the animals.
• The heat detector should spend at least 30 mins with the cows, at least twice a day. With bigger herds it may be necessary to spend more time detecting and to visit the herd 3 or 4 times a day.
• Identification – cows must be ear-tagged or easily identifiable. Mistakes occur when the heat spotter has not identified the correct cow.
• Place – small areas, such as the dairy holding pen, are not suitable. Cows under close confinement are less likely to try and mount others and show other heat signs. The best place is an open paddock, and the cows should be moved quietly and gently, with no rough handling or loud noises.
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Myths about artificial insemination among farmers:
• Farmers think that conception rate is less than natural service.
• Bellowing is the only heat sign.
• While animal in silent heat cannot be inseminated.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
Reference-On Request.
