What to consider if you want to AI sheep
Newcomers must not underestimate the importance of careful pre- and post-insemination management of ewes.
That’s the advice of Cumbria vet Andrew Hambleton of Paragon Veterinary Group, who says flocks embarking upon AI for the first time must set out a strict plan of routine flock managements tasks well ahead of the start of the AI programme.
Read advice on the advantages of using AI, how best to select ewes, timing and semen collection.
See how Cumbrian sheep producer Jim Pedley uses AI across his pedigree and commercial flocks in the case study.
See also: AI helps farmer secure early lamb market
Selection of AI candidates
Dosing or foot-trimming or giving any other treatments must be done [in advance] so that ewes have to settle, which means that planning well ahead is crucial.
Choosing the correct animals is also key to the programme’s success.
“It’s also important to be strict about the ewes being selected for AI and to focus on those that have had a healthy, trouble-free breeding history. Any ewes that have suffered health issues, difficult lambings or bad feet should not be included,” advises Mr Hambleton.
Body condition scoring should be carried out as an initial assessment.
Ewes need to be in body condition score 2.5 to 3 when inseminated so it’s important to allow enough time for any changes to be made to grazing regimes to improve the condition of thinner ewes, advises Mr Hambleton.
Assessing the body condition of ewes bound for an AI programme needs to be done once lambs have been weaned, he adds.
See also: Advice for body condition scoring
“But as well as making sure ewes are in the right condition once lambs have been taken off, this is the best time to do an all-round health check and to identify any ewes needing foot treatments. “
Assessing trace element profiles by blood sampling a random batch of the ewes is also very important as any deficiencies could adversely impact conception rates.
“It’s worthwhile speaking to your vet and to taking blood samples from a random selection of ewes from the AI group. The mineral status of ewes is critical and must be checked early. If a bolus treatment is necessary it needs to happen six to eight weeks ahead of the AI date.
“Selenium and cobalt, as well as vitamin E deficiencies, are the most critical in terms of fertility.”
The aim should be to collect blood samples from a range of different ewes within your prospective AI group, says Mr Hambleton.
Producers should also discuss any risks associated with toxoplasma or enzootic abortion with their vet and ensure all relevant vaccinations are given at least four weeks ahead of insemination.
For four to six weeks prior to tupping, ewes should be kept on good grazing and perhaps fed a small amount of a high energy feed such as sugar beet – although that depends on the number of ewes in the programme.
“But avoid grazing ewes on swards that are high red clover to avoid raising oestrogen intake levels.
“Once all the necessary routine treatments have been carried out ewes should be left alone for at least four to six weeks before the AI programme starts. The next time they are gathered it will be for sponges to be inserted to begin the synchronisation programme.”
AI timings
Working backwards from the selected lambing date, sponges should be inserted 14 days ahead of the actual date of insemination, explains Mr Hambleton.
Sponges are removed after 12 days and the ewes are injected with Pregnant Mares Serum (pmsg). On day 14, the ewes are inseminated.
Which type of semen you use should also be considered as this can affect how many rams you must use.
“The majority of the semen we use is fresh or frozen but most will be fresh. When it’s fresh it allows a flock owner to use a ram over a much larger number of ewes – say 100 ewes or more rather than 30-50 it would cover in a day by natural service.”
The cost of AI
The cost of AI can be between £10-£20 a ewe, but this can vary from flock to flock as costs are based on a “tiered” system that is dependent upon the number of ewes in the programme. And then there is the added cost of the semen collection.
“Some tups will provide enough semen from one collection to use on 100 ewes whereas others may need up to seven or eight collections, so it’s not easy being specific on total costs.”
The advantages of AI
One of the biggest advantages of AI is being able to use superior genetics across a larger proportion of the flock. However, labour requirements need to be considered too.
“More labour is needed at lambing [although] those costs are concentrated over a short time.”
Average conception rates of 70-80% can be expected when using fresh semen although success hinges on ewe selection.
“There is no significant correlation between ewe age and rates of conception, but clearly the older a ewe the more likely she is to have had some issues – say a difficult lambing – that may have been forgotten about but which may affect her current level of fertility.”
Semen collection – considerations
Semen can be collected from most tups three or four times to provide a day’s insemination needs but it’s important to have a semen check undertaken in advance of the AI date.
“Don’t take risks and assume a tup is fertile. Take a semen sample about two to four weeks prior to collection – even though a tup may have been a successful sire previously. It’s not unheard of for a tup to have picked up an infection over the summer that can affect its fertility.
“And remember too that some tups can be ‘shy’ about having semen collected so it’s worthwhile making sure all tups are used to having people around them before the collection day.
“And always have a back-up. While it may be that there is one particular tup that is being relied upon as the principal sire, it’s essential to have several tups available just in case,” says Mr Hambleton.
Case study: Jim Pedley, Little Musgrave, Cumbria
More lambs born and easier management through the spring and summer is why Cumbria sheep producer Jim Pedley uses AI across his pedigree and commercial flocks.
“We’re getting up to 90% conception rates with our pedigree Blue-faced Leicester and Texel ewes and the Swaledale ewes we AI’d scanned 200% this year so we reckon we are producing more lambs by using AI,” says Mr Pedley, who farms with sons Stephen and Martin at Woodhouse Farm, Little Musgrave, Kirkby Stephen.
Not only are the Pedleys able to use their choice of Blue-faced Leicester ram genetics over a larger number of Swaledale ewes to produce North of England Mule lambs, they believe the long-term advantage of concentrated lambing are significant.
“We used semen from two Blue-faced Leicester tups last year on 250 Swaledale ewes so we get a better run of Mule gimmer lambs and improved consistency when we come to draw them for the sales.
“Through the spring and summer we’re managing lambs that were all born with four or five days of one another – and that makes a big difference.”
The Pedleys, who use Paragon Veterinary Group for their AI programme, start lambing their pedigree flocks on March 1st but ewes and lambs are kept inside until mid-April. Swaledales start to lamb on March 25th.
“We get everything lambing at once so it means it’s pretty full on for four or five days at each lambing time. We’re with them 24-hours a day, but it’s well worth the effort.”
The Pedleys have been using AI for about seven years. The Pedleys are using both fresh and frozen semen and have been achieving similar conception rates at 80-90%. New Blue-faced Leicester tups are assessed on their first season progeny (born by natural service) and if good enough are then used to produce semen for the AI programme.
Mr Pedley says one of the problems they used to have with pedigree Texels bred by natural service was single lambs and difficult lambings.
“Since we switched to AI we get more twins, but they are easier to lamb. I put it down to the PMSG injection which improves fertility. But any ewes that don’t hold to AI don’t come into the programme the next year. We’re definitely getting a higher lambing percentage in the Swaledales by using AI.
“Getting ewes in the right condition after lambs have been weaned and making sure you’ve got plenty accommodation for lambing ewes – and enough labour – are very important for anyone considering AI.”