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Watch: Mating precision as 500 ewes serviced in Kilkenny
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Watch: Mating precision as 500 ewes serviced in Kilkenny

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AI in sheep is uncommon, but farmers working with Sheep Ireland have just inseminated over 2,000 ewes. Peter Varley reports.
AI in sheep is uncommon, but farmers working with Sheep Ireland have just inseminated over 2,000 ewes. Peter Varley reports.

Artificial Insemination (AI) is commonplace in suckler and dairy herds, but its use is more limited in sheep flocks due primarily to prohibitive costs and variable success rates.

Last Saturday, the Irish Farmers Journal visited A Farmer Writes contributor Brian Nicholson to see laparoscopic AI in action. The farm, located in Johnstown, Co Kilkenny, is taking part in the central progeny test (CPT) programme run by Sheep Ireland.

The CPT programme is in its sixth year using AI, with in excess of 2,000 ewes inseminated per year. The process is no easy feat, especially when you take into account rams also have to be quarantined and trained to deliver semen for four weeks before inseminating.

As Eamon Wall from Sheep Ireland explains, the practice is worth the effort, as it delivers invaluable breeding information that is central to improving breeding in the national flock.

Background to CPT

The aim of the CPT programme is to improve the accuracy figures for the €uro-Star index and to help accelerate the rate at which top genetic sires are identified, based on performance data of a ram’s progeny on commercial farms.

Since 2009, the programme has used semen from rams on commercial flocks that have a very high standard of animal performance recording.

In the early years of CPT, the goal was slightly different to the current one. The primary aim was increasing the amount of information across all the bloodlines (high- and low-starred rams) in order to create genetic linkage across all the breeders in LambPlus. This goal was deemed to be at an acceptable level after 2013 and so the criteria was changed to try to identify the best bloodlines for breeding replacement ewe lambs.

Eamon says the reason behind using high-index rams is that their progeny’s performance can be scrutinised at a commercial level and the data obtained from these farms can be fed back to the animals’ indices. This increases the reliability of important production traits and identifies top-performing animals that will improve breeding in pedigree and commercial flocks.

“Our hope is that by proving the ram’s accuracies in the CPT, we can then go further down the line of promoting the use of those rams to pedigree breeders,” explains Eamon.

The main reasons AI is used for the programme are:

  • The number of progeny each ram produces is increased hugely compared with natural service, which means better data can be obtained.
  • Having ewes lambing down in a short period means the data selected for comparing progeny performance is much more accurate, as each lamb should be subjected to the exact same conditions (removes any environmental bias caused by a significant spread in lambing dates and aspects such as weather and grass availability).
  • Shared benefits

    Brian Nicholson says one of the main reasons he joined the CPT last year was because he likes the idea of a very condensed lambing period.

    This year, he is going to inseminate 500 ewes artificially and with an almost 80% fertilisation rate from the AI service in 2014, he expects over 400 ewes will be lambing over a 10-day period next spring.

    “Having a compact lambing period by synchronising the ewes means I can plan labour much better at lambing time,” Brian says.

    He also likes the fact that high replacement index rams are being used on his flock.

    “This should help increase the genetic merit of my own lambs that I will be keeping on the farm for breeding.”

    Brian keeps meticulous records at lambing time by electronically tagging lambs once they are born and matching these lambs to their mothers on a sheep management system.

    He records key data such as lambing difficulty, birth weight and weight at 40 days, 100 days and 150 days (unless already sold).

    By using electronic tags and a computer recording system, Brian knows the sires and dams of each lamb and he will base sire and dam selection the following year on the performance of those lambs.

    Brian’s recording skills in turn help the CPT programme because he will pass his lamb’s performance records on to Sheep Ireland. It will be able to see how each ram’s progeny performed and even more farmers will benefit from the data produced, as it will improve the accuracy of the €uro-Star indices.

    AI process

    There are various methods of AI available, with the most common being laparoscopic AI, with some cervical AI now being used. Laparoscopic AI is used for the CPT programme and is seen by Sheep Ireland as the most suitable practice to optimise fertilisation rates.

    Watch a step-by-step video of the process below:

    The timeline for synchronisation and laparoscopic AI on Brian’s farm is as follows:

  • 3 October: Approximatively 250 ewes were implanted with a progesterone sponge in the vagina (two weeks before AI took place). The sponges were inserted to synchronise cyclic activity of the flock. Brian inserted the sponges himself using a special tube and syringe.
  • 15 October: The sponges were removed by giving a firm and slow pull to the strings attached and the ewes were injected with PMSG at a rate of 400iu/ewe. The PMSG was used to increase ovulation rates and in turn hopefully increase the litter size of the ewe if she was successfully mated.
  • 16 October: The ewes were kept indoors and were given restricted access to forage and water for 24 hours to prepare for laparoscopic AI. Rams were in the shed next door to create the ram effect. The rams’ natural male pheromones help to set off the ewes’ reproductive systems and complements the effect of the removal of the progesterone sponges.
  • 17 October: Sheep Ireland transported rams rated as five-star on the replacement index to the farm (these rams were sourced from private breeders and put in quarantine for a month in advance). During this quarantine, rams were trained to produce semen for AI. Twelve rams were selected for breeding for Brian’s flock from the Texel, Belclare and Suffolk breeds.
  • On the day of AI, Ronan Gallagher from Prostar Genetics, Co Sligo, took fresh semen samples from the rams present. This semen was used to serve the 250 ewes that were brought into heat following sponge removal two days previously. A ram was selected from the six present and let into a pen with a ewe in heat. As the ram went to mount the ewe, an artificial vagina connected to a plastic collector and tube was used to collect the semen.

    Ronan says generally over one millilitre of semen collected from a ram is a good quantity in one jump.

    Once collected, he takes a small sample of the semen and puts it under the microscope. He grades the semen from one to five on factors such as motion, viability and vigour, with five being the best quality.

    Good-quality semen is diluted with a dilutant made up primarily of egg yolk to increase the amount of ewes the semen sample can cover. One millilitre of semen from the ram can be diluted to 10ml and this will easily cover 50 to 60 ewes.

    The semen and the dilutant were stored in a warm water bath at body temperature of 35°C.

    All the ewes were given a sedative to relax them before the procedure was carried out. Just before AI, the ewe was put up on a special trolly to keep her as steady as possible before work began and make her abdomen freely accessible.

    The ewe was clipped and surgically prepared. A small incision was made on the left and right hand side of her stomach. On the left, a 10mm trocar was used to make the incision a couple of centimetres in front of her udder and on the right, a 5mm trocar was used. On the left, the scope was put in and connected to a light source and acted as a mini camera.

    Gas was also pumped in this side to help displace the stomach, bladder and intestine so that it was easier for Ronan to see the womb.

    Once the way was clear, the AI gun was placed into the right-hand side and 0.1ml of semen was injected into each uterine horn. The two trocars were removed and there was no bleeding whatsoever.

    The insertion sites were tiny and there wasn’t any need for a stitch.

    Antibiotic spray was used on the sites and ewes were given an antibiotic injection to prevent any risk of infection. The remaining 250 ewes were serviced a few days later with the same procedure.

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