The Cool Sheep Feature Career

ARTIFICIAL INSEMINATION IN SHEEP

- A Career in a Growing Industry

By: Kate Munro
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Kate Munro worked for Genstock, a sheep genetics company, for two and a half years as a technician. In 2006 she began studying for a Science degree at Charles Sturt University, Wagga Wagga, NSW
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Artificial Insemination in sheep has widely broadened the sheep industries scope and genetic potential within the breeding circle. Laparoscopic insemination rather than cervical insemination is most widely used and tends to have a better result or stick rate within the 6-8 week recommended scanning time.

Laparoscopic AI was discovered in the early 1980’s. A development on from cervical AI as a sheep’s cervix is very corrugated and hard to penetrate so the accuracy from the inseminators point of view can be decreased – also because the inseminator cannot get as close to the uterus as with laparoscopic AI - the semen has to do a lot more work in swimming up through the cervix etc to meet with the released egg – so the semen can lose motility and therefore lose viability to fertilize the egg, making the procedure of cervical AI perhaps less effective than laparoscopic AI. Laparoscopic AI bypasses the cervix by punching a 7 mm hole straight through the abdominal cavity – so a laparoscope can be inserted for the inseminator to look at the uterus – seeing if the uterus is turgid and a bright pink – and that some or both of the ovaries have ovulation sites on them. By actually visualizing the uterus we can see the two horns and the ovaries – so the semen can be directly injected into the correct part of the horns, making it less work for the semen so sperm can survive for longer – and if there is any early ovulating ewes within the group or later ones the semen has more of a chance to meet up with the egg.

To program the ewes up for an AI program it involves the insertion of an intra-vaginal sponge (for older ewes that have had a lamb before or heavier meat breeds) or a cidr (for maiden ewes or for finer woolled sheep).There are applicators for this procedure to suit both types of intra-vaginal devices. These devices are used to block the ewes from cycling. They are then removed 12 days later and an injection of folligon is given in the muscle to stimulate the ovaries. The amount of folligon is determined by the weight and general fertility of the flock, and sometimes even seasonal conditions. If given too much folligon then the ewes will have problems with too many multiples, and if the producer does not scan the ewes then ewe loss during lambing with be extreme. So it is important to get the dose rate correct for each individual flock. The injection will effectively synchronized the ewes so they can all be inseminated on the same day. Semen is injected directly into both uterine horns via a special pipette. So basically from the time of sponge insertion to AI date is a 2 week program. Up to 350 ewes can be inseminated in one day.
Conception rates can vary depending on the time of the year, but generally a rate of 70 to 75% should be achieved with a lambing percentage of 100%. Obviously a lot of factors play a part in obtaining a good lambing percentage – feed of a rising plain of nutrition – I recommend 250g of lupins every second day for 4 weeks prior to the day of AI. Lupins are the best source of protein and are safe to sheep – also a fantastic ‘fertility drug’! Weather, general stock management – no dogs around the ewes prior and post insemination is a general rule we enforce so not to stress the ewes at all. Semen quality, motility and concentration plays a part in a good result, fresh or frozen semen can also effect the conception. Timing of the producers plug pulling and injection is crucial as it all correlates to synchronizing of the ewes. Utilizing laparoscopic insemination gives breeders greater flexibility by allowing them to maximize production from their top proven sires or to access superior genetics outside their own flock.

INTERESTING FACTS

Semen comes in pellets and straws – 1 pellet = 3 ewe doses. 1 straw = 1 ewe dose. A pellet is more concentrated than a straw so you can get more ewe doses out of it. Most cattle AI centers use straws. Export though AQIS (Australian Quarantine and Inspection Service) Australian AI centers must have appropriates. Semen can be exported to New Zealand in pellet form but to any other country in the world it must be in straw form. The ram must also be quarantined for the appropriate time for the particular country and to have the specified tests to OK that semen to be transported overseas.
There are many Artificial Insemination centres across the country specializing in AI, Embryo Transfer, Semen Freezing – processing and collection, licensing and export semen and embryos, sheep management and advice & wool testing.
The AI season generally runs for 7 months of the year – from September for the meat breeds like Poll Dorsets and Border Leisters. November, December, January is the typical Riverina joining, autumn is the time where the fine woolled sheep mainly join, in western Victoria, Yass, Armidale etc. So the season ends around May.
We can AI 350 ewes a day, you can use as many rams as you want, depending on your genetic breeding program, your stud stock advisor/classer etc.
We can collect rams on farm – fresh and use that semen. But, generally we like to advise clients if they have a top sire, proven or otherwise to collect semen from a ram for insurance factors – if the ram dies or goes infertile etc.
We can flush around 30 donor ewes per day, plus implant the viable embryos recovered – Merino ewes usually average between 8-10 transferable 6 day old embryos. Meat breeds like East Friesian, Finnish Landrace 10-12, Samms, Poll Dorset and Texel average 4-6 embryos, Damara and Dorper average 5-7 embryos. Maiden ewes across the board tend to average less.
Embryos are 6 days old when you transfer them – we AI the donors 6 days before they are surgically flushed. The recipient or surrogate ewes are programmed up to think they are pregnant with a 6 day old embryo when we transfer the embryo.
Last season, being the 2004/05 AI season – we AI’d 35,000 ewes. Flushed 650 donors and transferred 3000 embryos.
The company Genstock Australia – we have a centre at Jerilderie NSW and in Hamilton VIC. We travel all over VIC, into some of SA and all of southern NSW up to Crookwell and Goulburn, out to Ivanhoe and we cover some of Cooma.
Once frozen in Liquid Nitrogen semen lasts indefinitely.
In the 2003/04 season I used semen that was frozen 30 years ago for a client around Forbes. AMAZING!
A rams ejaculate is usually 1ml. We collect a ram twice a day in the ram shed. 1 ejaculate makes 20 pellets, so that’s 60 ewe doses. That means he would normally jump 1 ewe with that ejaculate in normal natural mating, but with the introduction of AI etc we can cover much more and more efficiently. No wonder a ram is so knocked up after joining and lost a lot of condition!
First ejaculate of a ram is always discarded – it is like a clean out- it usually is a little sluggish and has a fair bit of crap in it.
You can use an electro prod to obtain the semen if the ram will not work naturally for you – it is a last resort. It stimulates the prostate gland to release the semen.
Semen is diluted with a special cryoprotectant to enable it to survive during freezing. Almost 50% of semen dies during the freezing process, but when thawed out it is still viable and motile enough to use for AI.
When semen is diluted after collection it is cooled slowly over several hours and frozen into pellets or straws and plunged into liquid nitrogen at minus 196 degrees Celsius.
After freezing we evaluate all ejaculations separately to determine motility and percent alive – if at a high standard we keep the collection. To do this we thaw 1 pellet from each collection and incubate it in a water bath set at 37 degrees for 3 hours to simulate it being inside the ewe. If at a low standard the semen is discarded. Owner tells us how many doses/pellets he wants to keep; it is then placed into a long-term storage tank until required by the owner.
Owners of rams may retain semen marketing rights – if specified at the sale of the ram.
Ewes when AI’d are given a small sedative called Xylium Zylazil. Again dose rate is determined by weight and also heat during that day. It is an S4 drug, so it can kill a sheep if they are given to shots in the muscle. It is a muscle relaxant, so it restricts the air flow to the lungs, and when tipped up in the AI cradle they can really struggle for breath. We always show the owner etc how to use the drug properly. There is however a reversing drug you administer into a blood vein. Ewes are injected 10-15 min ahead of AI so that the sedative is given time to work through their system. They certainly don’t kick as much in the cradle with the sedative. AI is not a painful procedure; sheep mainly do not like being restricted in the cradle and tipped upside down.
You use some egg yolk to help coat the semen during the freezing process in the diluent.
When AI’ing out in a shearing shed – we basically have a portable lab where we set up on a wool table etc. One water bath is set at 37 degrees and the other is at 30 degrees. We thaw into the 37 degree one and hold the semen in a test tube rack in the 30 degree one. We thaw 3 pellets at one time. So we can get 9 ewes to one thaw – usually can pick up one extra ewe dose per thaw though. The reason why we only thaw one pellet at a time is that we don’t want the semen to be sitting in the test tube wasting energy while we are AI’ing- as we do about 50 an hour. So I just thaw semen every 10 or so sheep to keep it fresh and so I can keep an eye on how many ewes I have to each ram and how many we have done.
Studs generally use AI and Embryo Transfer the most, but a lot of commercial properties over the years I have worked for Genstock have taken it on as another device to enhance their flock. Generally they pick out the best 250-300 ewes and AI them to their chosen ram/s and go through the progeny and keep the best portions of those and rams to use in the following year for joining. In a way it can be cheaper than buying a heap of flock grade rams from studs.
A lot of clients have rated the fact that you can assess or class the lambs or progeny at a younger age as they are all born within a week. They have also noted that you really assess your ewes and their genetic potential, as it is not generally a cheap exercise if you get it wrong! When the clients mother the sheep- you can then follow the breeding and record sire and dam of that progeny, so you can have a much better idea of where your flock is headed.
With AI and ET (Embryo Transfer) however, you must be careful of the weather conditions when the due date for the ewes to lamb is, as they all lamb down in a flurry. Some may come, generally multiples arrive a few days early to the 5 month gestation and some may come late. But we advise that owners bait for foxes preceding the due date, put the ewes in a sheltered paddock, keep checking and monitoring them every day and keep feeding a normal ration rate, depending on season.
Ewes that are AI’d or are recipient ewes should be scanned at a minimum of 6-8 weeks after insemination and transferring.
Embryos can be frozen immediately after flushing or they can be chilled fresh and loaded into and equitainer (it has special ice bricks to slow the development of them down). They have to then be transferred in a space of 24 hours.
I have been lucky enough to be asked to fly with Samm (South African Merino Mutton) embryos we had flushed in Wagga Wagga to South Australia and put them into programmed recipient ewes.
We also were involved in putting Samm embryos in that were flushed by Genstock WA in Western Australia and we put them in the next day in Grenfell NSW. The scope of the whole process is unlimited.
It’s amazing when you AI or ET a ewe that you have previously created through the same process. It’s a real cycle! It’s a great thing to be able to follow the clients flock and monitor the genetic gain.

Overall Artificial Insemination allows breeders a greater flexibility by giving them the scope and opportunity to maximize their enterprise and production from their top sires or from superior outside genetics or proven genetics. How great it is to be able to join 300 odd of your best ewes to whatever ram that you decide on the same day, so that they all lamb down in a similar time. I have so enjoyed my time working with Genstock Australia, the people that I have met, the places I have traveled for work, the sheep I have seen was the best experience and makes me even more committed to promote sheep and wool in Australia as we have a wonderful product that provides and fantastic lifestyle for all concerned. We have the best sheep and wool in the world and our product is the best it’s ever been – we just need to market it more effectively, efficiently and appropriately to the commercial world.

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