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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 be receptive.

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.

Labour
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 period.

Inseminator
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 work!!

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 in oestrus.
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 observed.

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.

Alternatives include
1. Single PG Regime Ð Suitable for Heifers and cycling Cows with Calves
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 Calves
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 post calving
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 heat signs.
If multiple cows are being inseminated to the same bull then splitting straws between cows and double inseminating twelve hours apart can increase conception rates

Day Zero - Insert CIDR's to cows and administer 2ml of CIDIROL injection.-morning
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 morning)

POST AI

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.






 


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