Some factors affecting pregnancy rate in ewes following laparoscopic artificial insemination.
Authors: McCappin N, Murray R D
Journal: The Veterinary record
Summary
# Editorial Summary: Factors Affecting Pregnancy Rate in Ewes Following Laparoscopic Artificial Insemination McCappin and Murray's investigation of 646 ewes across 13 commercial flocks using routine laparoscopic artificial insemination identified several modifiable factors influencing reproductive success, with an overall pregnancy rate of 66 per cent but considerable variation between management approaches. Frozen semen achieved significantly superior conception rates (70 per cent) compared with fresh semen (58 per cent), whilst ewes transported to dedicated artificial insemination centres showed markedly better outcomes (74 per cent) than those inseminated on-farm (62 per cent), suggesting that environmental consistency and reduced pre-mating stress may play important roles in fertility. Notably, the highest doses of equine chorionic gonadotrophin for oestrus synchronisation (>400 iu) substantially impaired pregnancy rates, reducing them to just 49 per cent, indicating that synchronisation protocols require careful calibration. Most striking was the effect of pre-mating handling: ewes gathered, handled and treated four to six weeks before breeding showed pregnancy rates of only 54 per cent compared with 74 per cent in undisturbed animals, suggesting that minimising physiological stress during this critical window may be as important as the technical execution of insemination itself. For practitioners employing artificial insemination in sheep, these findings emphasise the importance of semen selection, strategic use of synchronising hormones, transport logistics planning, and protective management of ewes during the pre-mating period.
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Practical Takeaways
- •Use frozen semen for laparoscopic artificial insemination in ewes as it provides superior pregnancy rates (70% vs 58%)
- •Transport ewes to a dedicated insemination centre rather than performing on-farm procedures to improve conception rates by approximately 12 percentage points
- •Avoid high-dose equine chorionic gonadotrophin (>400 iu) for oestrus synchronisation as it substantially reduces pregnancy rates; use lower doses instead
Key Findings
- •Overall pregnancy rate was 66% in 646 ewes bred by laparoscopic artificial insemination, with highest rates (highest in ewes bred for the fourth time)
- •Frozen semen achieved 70% pregnancy rate compared to 58% with fresh semen (P≤0.01)
- •Ewes transported to an artificial insemination centre achieved 74% pregnancy rate versus 62% on-farm (P<0.01)
- •Higher doses of equine chorionic gonadotrophin (>400 iu) reduced pregnancy rates to 49% (P<0.001)
- •Handling and treating breeding ewes 4-6 weeks before mating reduced pregnancy rates from 74% to 54% (P<0.01)