Artificial Insemination (AI)
Modified by Neil Sanderson, Livestock reproduction
specialist and purebred Angus breeder
Setting Up a Program
Before you start, ensure the sire that you are preparing to use is registered
with the Association for use as an AI sire. (This ensures that his progeny
are 'registerable' and that he is free of genetic abnormalities.) It is
also pertinent to check with the semen seller that the semen has undergone
some basic quality checks by a reputable technician before you purchase
it. This should include analyzing viability and motility of the sperm
cells after thawing a straw.
To use artificial breeding in beef cattle successfully you must design
a program related to the requirements and resources of your herd. The
result you achieve will depend on a number of factors, most of which can
be controlled on the property.
If cows are cycling normally, the factor that causes most failures is
the problem of detecting cows in oestrus (heat). In well-managed programs,
conception rates of about 65 to 70 per cent can be achieved at the first
insemination and about 85 per cent at the second.
Suitability of Cows and Heifers
For a successful AI program, cows or heifers should be cycling normally
and have no reproductive abnormalities and, cows preferably had one heat
since calving. Potential candidates should be on a rising plane of nutrition
and most importantly have had no feed stress during the winter pre calving.
This means your program should begin at least 60 days after calving.
The cows should gain weight during this period. Aim for a bodyweight increase
of about 0.2 to 0.4 kg per day and, if necessary, use supplementary feeding
to achieve it.
Heifers should come on heat regularly before the program begins and have
a bodyweight of at least 300kg. Watch the herd for signs of heat for several
weeks before the program begins, to make certain that enough cows will
Do not use cows left over from a natural mating program. They will be
less fertile, and poor results are a certainty. Cows that have just calved
for the first time at two years are the ones under the most stress coping
with lactation and still trying to grow themselves so are not the best
candidates for an AI program. You will get better results with mature
cows that have already raised their first calf.
You need labour for detecting cows on heat, moving stock to the yards,
keeping records and inseminating. The people you employ should be good
cattle handlers and have a basic knowledge of AI. The number you employ
will depend on the number of cows in the program and the type of program
you intend to use. It is essential to have enough people to handle peak
You must be proficient in your own right or employ a competent inseminator.
You will most likely employ the local veterinarian or arrange to have
yourself or one of your staff trained as an inseminator. Most areas have
competent Dairy Inseminators working on contract who will assist in Beef
AI programes Training courses are conducted regularly - contact your local
AgriQuality Ltd, or local semen processing company eg. Ambreed or LIC.
Yards and Holding Paddocks
In an AI program you have a limited time in which to inseminate the cows.
Your holding paddocks and yards must be well equipped, in good order and
large enough to handle peak numbers of cows in the time available.
A crush 660mm wide with a vet gate behind to allow easy access for the
inseminator is essential. It is preferable not to bail the cow for insemination,
so use a chain or rail behind the cow to prevent her moving back.
The crush area should be roofed over so that insemination can proceed
regardless of weather.
A small shed near the crush is useful for storing semen and recording
sheets. A supply of water for washing the equipment is essential.
Cows should be held fairly close to yards during the program because
considerable time is spent going back and forth checking for cows on heat
and moving cows in for insemination.
If suitable paddocks to handle the number of stock for the duration of
the program are not available close to the yards, some form of feeding
may be necessary. The use of oestrus synchronisation programs can reduce
the load on adjacent paddocks.
Any holding paddocks for an AI program must be secure and well away from
all Bulls. A mob of synchronized cows or heifers acts like a powerful
magnet for bulls which can soon upset the best laid plans for your AI.
Natural Heats versus Synchronised Heats
The conception rates achieved from AI in cows or heifers comparing the
use of naturally occurring heats and those induced by hormonal intervention
or synchronized heats should be the same if the principals outlined above
are adhered to.
Oestrus Detection and Time of Insemination
Regardless of how well planned the AI program is, if the animals are not
detected in oestrus and inseminated at the proper time, it just doesn't
Cows come into oestrus approximately every 21 days (range 18 to 24) during
which time they are receptive to the bull. Oestrus lasts 18 hours in cows
and only 6 to 12 hours in heifers.
The best time to inseminate the cow is 12 to 24 hours after the onset
of oestrus, that is, towards the end or just after the end of oestrus.
In practice, cows first seen in oestrus in the morning are inseminated
in the afternoon, and cows first seen in oestrus in the afternoon are
inseminated the following morning.
Cows must be observed at least twice a day during the AI program, in
the early morning and late afternoon, although a third observation at
midday is usually worthwhile. Cows in oestrus are moved to the yards for
insemination. Use of heat detection aids like tailpaint or adhesive colour
patches are thoroughly recommended
A suitable schedule would be:
> Daylight to 7.00am. Detect and cut out cows on heat.
> 7.30am to 8.30am. Inseminate cows cut out on the previous afternoon
> 3.00pm to 4.00pm. Inseminate cows cut out that morning.
> 4.00pm to 6.00pm. Detect and cut out new cows on heat
Oestrus is best detected by riding / walking quietly amongst the cows.
If necessary, herd them into a corner of the paddock where they can
be watched for a while. Spend plenty of time observing for oestrus behaviour
in the mob (half an hour at least is recommended).
Cows on heat, or coming on heat, will usually gather together and form
a restless group and show some or all of the following signs:
> Restlessness. Walking around from one cow to another, bawling
and trying to mount other cows.
> A clear watery mucous discharge from the vulva.
> The vulva becomes swollen and moist.
> Indications of being mounted, such as roughened hair over the rump
and mud marks in the flank.
> Standing to be mounted by other cows. this is one sure sign that
the cow is in full oestrus (standing heat).
Aids to Oestrus Detection
There are a number of methods that can be used to aid in detecting cows
Vasectomised bulls (teasers) will display the sexual characteristics of
an entire bull but are infertile. They will seek out cows in oestrus and
thus form a readily identifiable group.
The benefit of using vasectomised bulls is increased if they are fitted
with a chin-ball marking harness. The harness consists of a ball-operated
paint reservoir, which is strapped under the chin so that when the bull
mounts, the cow is marked over the hindquarter with the paint.
About 3 vasectomised bulls per 100 cows are needed to unsynchronised programs
and 5 to 8 vasectomised bulls per 100 cows for synchronised programs.
Because of the risk of spreading venereal disease, care must be given
to the selection and management of vasectomised bulls.
Steers treated with hormones can be used in place of vasectomised bulls
but they are not as reliable.
There are several brands of heat mount detectors available, which are
either plastic tube containing dye, which are glued onto the cow's rump.
When the cow is mounted, pressure on the tube releases the dye and the
cow is identified. Other types are like a "Scratch and win"
pad glued on the cows rump. When ridden the top layer of paint is rubbed
off leaving a bright underlayer which is obvious. Heat mount detectors
are about 85 to 90 per cent accurate.
Specially formulated paint (tail paint) applied over the top of the cow's
tail is also a detection aid. When cows are mounted the paint is rubbed
off and the cow is conspicuous.
Most heat detection aids are available from stock and station companies,
local veterinary practices or semen sellers.
Synchronising Oestrus for AI
New Zealand leads the world in both research and application of artificial
breeding and synchronized breeding programs in Beef and Dairy cattle.
There are currently several programs using various reproductive hormones
that are successful for synchronization of either cycling or non cycling
beef cattle. It is possible to condense calving patterns and synchronise
non cycling lactating cows as soon as 35 days post calving but results
here may be variable. Programs can be designed to accommodate most clients
wishes in terms of labour inputs and financial obligations. Please communicate
with your local vet to design the program to suit your needs.
Synchronisation pays where skilled labour for oestrus detection and/or
insemination is very expensive, or where feed is short and stock cannot
be held close to the yard long enough for natural oestrus cycles to be
Prostaglandin (PG) is a restricted and dangerous drug available only
through a veterinary practitioner, and will cause abortion if the cow
is in calf and is dangerous if injected or comes in skin contact to the
operator. The drug is ineffective unless the cows are cycling normally;
they must have been on heat at least once since calving. Prostaglandin
is relatively expensive and should be used with this in mind.
1. Single PG Regime Ð Suitable for Heifers and cycling Cows with
A simple partial synchronization program is to tail paint the mob and
observe for oestrus behaviour for a period of 6 days and inseminate all
cycling cows over that period. On the afternoon of day 6, all non inseminated
cows can be treated with the hormone Prostaglandin (PG) by a veterinarian.
Continue to observe twice daily and inseminate to detected oestrus with
a significant group of synchronized heats expected at 48-72 hours after
PG.If cows or heifers are all cycling prior to this program, expect one
third of mob to be AI'd in first 6 days with two thirds having to be synchronized.
2 Double PG Regime Ð Suitable for Heifers and cycling Cows with
If cows or heifers are all in a naturally cycling group they can be brought
in and given a dose of PG on day zero. Approximately 2/3 of the mob should
show oestrus in the 48-72 hours following injection. Either, all cows
that have shown oestrus can be inseminated at this time and removed from
the mob to go with a follow up bull or they can be ignored and then the
whole group given PG on day 11. If the first group were AI'd and removed,
then just give PG to the remaining group that did not cycle to the first
injection on day 11.
3 CIDR Regime Ð Suitable for Heifers
CIDR's are hormone infused intravaginal inserts that when inserted carefully
into the vagina of a cow or heifer prevents oestrus through the release
of the hormone Progesterone.
A very successful method to synchronise a group of cycling heifers is
to insert CIDR's on day zero and leave in the heifer for 8 days. On the
afternoon of day 8 administer PG and remove the CIDR. At this time paint
the heifers tail or use a heat detector or introduce vasectomised teasers.
Oestrus should occur by the morning of day 10. Inseminate the heifers
12 hours after standing heat is observed. Some variations to this program
may be recommended by your own veterinarian
4 CIDR Regime - Suitable for Cows with Calves. May work at 35 days
This program is time consuming and requires several visits to the yards
with cows and calves but in the authors herd has been very effective with
satisfactory pregnancy rates.
This program has given satisfactory results in non cycling cows that are
in good condition and on a rising plane of feed. It can also give satisfactory
results when cows are AI'd on the pm of day 9 even in the absence of obvious
If multiple cows are being inseminated to the same bull then splitting
straws between cows and double inseminating twelve hours apart can increase
Day Zero - Insert CIDR's to cows and administer 2ml of CIDIROL
Day 6 - Administer PG in afternoon.
Day 7 - Remove CIDR'S in afternoon
Day 8 - Administer 1ml of CIDIROL and tail paint, attach heat pad
or introduce teasers in the morning.
Day 9 - Observe oestrus and AI (majority of cows on heat early
After the program, the cows are usually run with a "clean-up"
bull to cover those cows that did not conceive to AI. At least 21 days
should elapse after the AI program is concluded before clean-up bulls
are used if sire parentage of the calves needs to be known.