Semen quality is often blamed for the variable success of sheep artificial insemination programs but a leading sheep reproductive scientist Simon Walker says it is more likely poor ewe synchronisation.
“Semen quality is good enough and you probably won’t get much better in the next 20 years but the semen dogma has stopped us looking at other factors,” he said.
Dr Walker- the former principal scientist at SARDI’s Turretfield Research Centre – told attendees at the SA Merino Sire Evaluation Trial field day, last week at Keyneton Station, it was more likely ewes were coming into oestrus outside of the preferred AI window.
Dr Walker gave an overview of a new research project he is involved in through SARDI at Turretfield, being funded by Australian Wool Innovation.
Its aim is to improve oestrus synchronisation in laproscopic AI programs by developing one or more new protocols.
He hopes it will address conception rates which can vary from 70 per cent to as low as 10-15 per cent.
“Some people are saying the results we are getting worse than 20, 30, 40 years ago and people are walking away from the technology which is a shame because it is very valuable technology,” he said.
He says simply using a progestrone CIDR and PMSG did not guarantee ewes would come into oestrus in a 18 to 20 hour period.
Dr Walker -with fellow researchers Dave Kleemann and Jen Kelly – are ultrasound scanning and studying the ovaries of many ewes.
The team hope this will enable them to come up with an AI protocol which is far more relevant to today’s sheep.
“When we can identify a set of ovarian conditions that are beneficial to the pattern of oestrus then we expect we can generate those conditions with the range of hormones we have available,” he said.
“We already have found out that we can definitely move the pattern of oestrus.”
Over the past 50 years Dr Walker says sheep have changed dramatically, particularly in their body weight, but the AI protocol has not.
“The (hormone) dose rates remain the same but the sheep are 20, 30 or even 40 kilograms heavier,” he said.
“The sheep are also fatter and tend to absorb the hormones, so do we need to look at that ?”
In coming months the team will also investigate the impact of ewe nutrition from weaning of lambs to time of AI on a successful AI program.
“There is substantial anecdotal evidence to suggest if that recovery period is not substantial in terms of the ewe regaining body weight then she will have a very bad synchrony where sheep come into oestrus over 4, 5, 6 or 7 days,” he said.
‘It doesn’t matter what sort of sperm you use- turbo charged or not – they will not affect fertilisation.”
Dr Walker praised the efforts of the SA Stud Merino Breeders Association for highlighting the issue and encouraged breeders who have used laproscopic AI in recent years to complete the nationwide survey they are collating.
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