ARTIFICIAL INSEMINATION (AI)

History of AI

The first major commercial AI program happened in Denmark in 1936 with more than 1,000 dairy cows & a success rate of 59% (which was interestingly better than natural service conception rates on that farm). In the 1940’s the technique took off world wide in most developed countries. Over the next 2 decades, the use of semen straws, semen extenders, improved insemination techniques and storage in liquid nitrogen (-196 degrees C) and the use of the AM/PM rule of heat detection and insemination (1948) all improved potential success rates & cost effectiveness of AI to a point not far from where we are today, some 50 years later.

Without AI (& embryo transfer) in the last 25 years, the Highland breed in Australia would still be floundering, and there would be no where near the quality of animals that we see today.

 

Why Use AI - The Pros

♠ Use of elite sires from Australia & overseas giving potentially faster genetic gain for your herd, and often access to diverse genetics to avoid in breeding.

Recent Elite Sires Introduced to Australia

♠ Potential for use of multiple sires over your female herd – one bull does not suit all cows.
♠ You may be able to eliminate need for a bull in small herds (2-3 cows).
♠ Cost effective for small numbers versus purchase cost of a decent Highland bull.

 

Why Not To Use IA - The Cons

♠ Labour intensive as heat detection is required and you need to organize an AI technician.
♠ Cost (of semen, drugs to synchronise heat (if used) and cost of AI technician) can add up with greater numbers, compared with just using a bull. Gauge on around $250 per try & with a 60% success rate & your own time/labour added in, an AI calf would end up costing at least $400-500 to get a calf on the ground. Compare this with around $100-200 per calf on the ground for a natural service (either as a leased bull, or $4,000 to purchase a quality bull used for 2 seasons on 10 cows).
♠ You still sometimes need a bull anyway as AI is not always successful in every female, even if done a 2nd & 3rd time (unfortunately success rates for the inexperienced breeder can be quite low).
♠ You are often using sires that are not necessarily proven (might have only seen a photo and maybe some growth statistics), so not every calf born to AI will be an improvement on your female. You still need to use selection pressure (cull) on AI calves that are not up to standard.
♠ This is only one side of the genetic equation – i.e. an elite AI bull used over a herd of average females, can only do so much (as compared with embryo transfer where elite cows and bulls can potentially be used).

 

Consider AI as a way of expanding genetics and getting access to good bulls, rather than as a way of getting your herd pregnant (you still should have a back up bull).

 

What Exactly Happens with AI?

► Females need to be cycling – normally at least 40-50 days post calving to consider an AI program. The age of joining Highland heifers is a personal choice but they should be around 400-450kg live weight. If they are already cycling, spontaneous or natural heats can be used with the AM/PM rule (or a two injection prostaglandin synchronisation program can be used). If they are 40-50 days post calving & in good condition, but not quite cycling, then a synchronisation program utilising a progesterone implant (CIDR) will bring most of them on (see Synchronisation Programs).

► Cows need to be kept in good condition (not too skinny, and certainly not obese). We need them to be in slightly better condition to maximise conception rates with AI (condition score 2.5-3.0 ideally), compared to natural service with a bull (condition score 2.0-2.5 would suffice). Remember that they will have calves at foot that are 2-3 months old that will be dragging them down. The rising plane of nutrition over the previous 4-6 weeks, may involve supplementary feeding, or free access to pasture. Interestingly here, energy content is more important than protein levels, and in fact too high a protein level (say >12%) will see slightly decreased conception rates.

 If animals are down in condition or the feed is just not there, it is nearly a waste of time and money considering an AI program. If one animal is particularly down in a group, the chance of getting her to cycle and then getting her in calf is dramatically reduced.

► Heat detection, whether spontaneous heats observed in your herd or programmed / synchronised heats, is vitally important and checking needs to be at least twice a day (ideally 3-4 times). Most cattle stand between dusk and dawn (68%) and the first sign of standing head (the critical moment to watch for) will mostly happen at sunset & sunrise. Cows and heifers come on heat naturally every 21 days (actually it varies from every 18-25 days), but they only allow others to mount them for 12-24 hours (often 6-8 hours for heifers). So checking for 15-30 minutes at least twice a day is essential. This means sitting and watching them (take a glass of wine or a cup of tea with you). There needs to be no distractions - so not at feed time and leave the dogs back at the house.

Timing here is critical as the insemination needs to happen 12-18 hours after the first signs of standing heat. The AM/PM rule has been used for a few decades now and has stood the test of time. If the cow is seen to stand for the first time in the evening, AI the next morning. If they are noticed to be standing for the first time in the morning, they are AI’ed that evening.

No heat detection is required for some synchronisation protocols (4 & 5 mentioned below in the table) because they are able to tightly synchronise the females so that most stand over a 24 hour period. All can be inseminated at the same time (usually approx 60 hours after the PG injection), or some will inseminate only those who have stood to that point in time (i.e. where heat detectors have gone off). Pregnancy rates of 50% can often be achieved with these methods. This is called 'timed AI'.

► The actual insemination is be performed by a vet, or an AI technician – experience here is the key to maximizing pregnancies. Ask around to see who other breeders in your area use to be sure they are readily available at call and that their success rate is good. If you are using a synchronisation program, you can tee up an ideal time for potential AI with your vet or technician in advance, so as to be sure they will be around.

You can do an AI course yourself, and while this is very useful, unless you are doing a certain minimum number each year, you may not have the success rates that you are striving for.

► Selection of the AI sire to use is the step that most of us procrastinate over. We must remember that there is no perfect animal (at least we have never seen one yet), but our goal is to try and match strengths and weaknesses in the sire and dam and hope it all comes together in the right combinations. Lets say that you have a female that has bad feet and poor muscle expression but has well laid in shoulders, a lot of hair and a beautiful horn set. You may want to choose an AI bull known to improve feet and muscling, although he perhaps lacks a little Highland character and he might be a little heavy in the shoulders. If you can not see the AI bull in question or have it inspected by someone independent, try and have a look at his progeny (say 5-10 of them to get a fair idea of what he throws) or even check any siblings of his. When looking at progeny, consider the quality of the females that he is used over. (see our thoughts on some of the AI sires available)

► Where to deposit semen? Thoughts on this have changed a little over time but best results are found when all of it is placed just into the uterus (0.5-1.0cm past the cervix) & slowly injected over  about 5 seconds. Experience is very important. The whole insemination should take no more than 1-2 minutes.

The two most common and manageable things that affect the success rate of AI programs, are nutrition and accurate heat detection.

 

To Synchronise of Not?

Where we want to decrease the time that we need to accurately observe the cows for standing heat, synchronization techniques are very useful. These techniques when used with the AM/PM rule for inseminating give basically the same pregnancy rate as observing spontaneous heats over 3-4 weeks and inseminating 12-18 hours later (that is around 60%). While watching for spontaneous heats is labour intensive, many breeders with just a few animals that can be brought into a paddock up beside the house, find that this is not a major hassle, is cheaper and they can avoid the need to handle drugs.

While the average across all studies over decades for AI pregnancy rates has always been around 60%, many breeders consistently report 80-90% conception rates – where special attention to nutrition, condition of the cattle and good stress-free AI technique is used. Heifers often give a slightly higher pregnancy rate in Highlands left to breed at 2+ years old.

Synchronisation Program	Average number of females that actually cycle	Average pregnancy rate	Days spent heat detecting
1) Single PG injection	80%	60%*	12
2) Two PG injections	80%	60%*	4
3) CIDR & PG	90%	65%*	3
4) EB, CIDR & PG Ω	95+%	70%*	1-2
5) GnRH, CIDR & PG  Ω	80-90%	50-70%*	1-2
6) None (spontaneous heats)	90%	60%*	25

* All of these figures can be improved upon by 10-20% in the right hands.
^Ω Can used with timed AI (but lower pregnancy rate by 10-15%). 
(for more detail on all these Programs - see synchronisation page)
Abbreviations: 
PG         = prostaglandin (Estrumate^®, Lutalyse^®)
CIDR^®  = intravaginal progesterone implant
GnRH   = gonadotrophin-releasing hormone (Fertagyl^®)
EB         = oestradiol benzoate (Ciderol^®)

 

Follow-up AI or a Mop Up Bull?

The decision to AI those that do not get pregnant from the first AI (on average 40% of the herd), or use a bull to get these in calf, is a dilemma. The success rates on subsequent AIs is always slightly reduced on the first round, and so if you have a bull, we believe this is the best alternative so that your calving period doesn’t string out too far.

A good idea is to put a new heat detector on the females after the AI, prior to putting them in with the bull, and the cows whose heat detectors do not go off 3 weeks after insemination are likely to be pregnant to your AI. Remember that as many as 5% of females will cycle and show standing heat wile they are pregnant (we have had one female do this to us on two separate pregnancies).

Pregnancy testing 12-14 weeks after the AI program will let you know who is in calf, and if you used a mop up bull, an experienced vet can pick which are pregnant to AI (the pregnancy is 3 weeks more advanced) and which are pregnant to the bull.

 

The Future of AI

Sexed semen

This was first performed in 1985 & the technique improved significantly in 1999, but still today is not utilised that much. It would be especially useful in the dairy industry but is not used a lot there even. The main reason for this is the reduced conception rate because of a reduced number of viable sperm (2,000,000 vs 25,000,000 tad poles) and so it is recommended to be used for heifers only and with spontaneous cycles (both of which allow marginally better conception rates in the dairy industry – expect 45-50% pregnancy rates here). The cost of this semen works out to be around 3-4 times more expensive as well.

Improved conception rates

With more research into how a cow’s reproductive cycle can be manipulated, it appears that we might head towards a timed mating after synchronisation, providing pregnancy rates can be improved upon here. Other than this, it is hard to see where improvements can be made, over and above what is currently being done, as things have remained basically unchanged for the last 30 years. The simple explanation for this is that science is not the reason for an average conception rate of 60%, human error is!

It is realistic to expect 80-90% pregnancy rates from AI if you have a good system and a good understanding of the factors that improve success rates (mainly nutrition and heat detection).

Referrences:

1) Great general article on AI - http://osuextra.okstate.edu/pdfs/F-3164web.pdf

2) Detail on the technique for AI if you wanted to see how it is done -  http://www.selectsires.com/reproductive/ai_technique_cattle.pdf

3) A vast array of oestrus synchronization techniques for some general reading - http://beef.unl.edu/learning/estrussynch.shtml