Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm.
Abstract: To evaluate factors contributing to fertility of thoroughbred mares, data from 3743 oestrous periods of 2385 mares were collected on a large thoroughbred farm in Ireland. Fourteen stallions (mean age 8.3 years; range 4-15 years) had bred 2385 mares (mean age 9.4 years; range 3-24 years). Maiden mares accounted for 12%, mares with a foal at foot for 64%, and barren, slipped or rested mares for 24% of the total. The mean pregnancy rate per cycle was 67.8% (68.6% in year 1 and 66.9% in year 2). Backward stepwise multivariable logistic regression analysis was utilized to develop two models to evaluate mare factors, including mare age, reproductive status, month of foaling, dystocia, month of cover, foal heat, cycle number, treatments, walk-in status and stallion factors including stallion identity, stallion age, shuttle status, time elapsed between covers and high stallion usage on the per cycle pregnancy rate and pregnancy loss. Old age (p < 0.001) and cover within 20 days post-partum (p < 0.003) were associated with lowered pregnancy rates. High mare age (p < 0.05) and barren, slipped or rested reproductive status (p = 0.05) increased the likelihood of pregnancy loss. Uterine inflammation or infection, if appropriately treated, did not affect fertility. Only high usage of stallions (used more than 21 times in previous week) was associated with lowered (p = 0.009) pregnancy rates. However, shuttle stallions were more likely to have increased (p = 0.035) pregnancy survival, perhaps reflecting a bias in stallion selection. In conclusion, mare age exerted the greatest influence on fertility; nonetheless, thoroughbreds can be effectively managed to achieve high reproductive performance in a commercial setting.
© 2016 Blackwell Verlag GmbH.
Publication Date: 2016-01-27 PubMed ID: 26815482DOI: 10.1111/rda.12655Google Scholar: Lookup
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- Journal Article
Summary
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The research assesses what factors affect the successful reproduction of thoroughbred horses on commercial stud farms. Main findings include that old age and premature coverings reduce pregnancy rates, while high usage of stallions and certain reproductive statuses increase the likelihood of pregnancy loss.
Methodology
- The data for the research was gathered from a large thoroughbred horse farm in Ireland. In total, 3743 oestrous periods of 2385 mares were analyzed. The mares were bred by 14 stallions, whose ages ranged from 4-15 years.
- The mares were categorized into three groups: maiden mares, mares with a foal at foot, and barren, slipped or rested mares. The mean pregnancy rate per cycle over a two-year period was calculated.
- Using backward stepwise multivariable logistic regression analysis, the researchers developed two models to evaluate mare and stallion factors that might influence the peri-cycle pregnancy rate and pregnancy loss. Factors analyzed for mares included age, reproductive status, month of foaling, dystocia, month of cover, and cycle number. Stallion factors included identity, age, shuttle status, time between covers and frequency of use.
Key Findings
- The research found that older mares (p < 0.001) and cover within 20 days post-partum (p < 0.003) were more likely to experience lower pregnancy rates.
- It also discovered that a higher mare age (p < 0.05) and barren, slipped or rested reproductive status (p = 0.05) increased the likelihood of pregnancy loss.
- Despite indications from previous studies, uterine inflammation or infection, if properly treated, did not negatively affect fertility.
- Only high usage of stallions (used more than 21 times in the preceding week) had a negative impact on pregnancy rates (p = 0.009).
- Interestingly, stallions that were used for shuttle breeding were more likely to have increased pregnancy survival (p = 0.035). The researchers suggest this might be due to a bias in stallion selection, with better-quality stallions being used more frequently.
Conclusion
- The biggest influence on a mare’s fertility was found to be age. Despite this finding, the researchers conclude that it is possible to manage thoroughbreds effectively to achieve high reproductive performance in a commercial setting.
Cite This Article
APA
Lane EA, Bijnen ML, Osborne M, More SJ, Henderson IS, Duffy P, Crowe MA.
(2016).
Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm.
Reprod Domest Anim, 51(2), 181-187.
https://doi.org/10.1111/rda.12655 Publication
Researcher Affiliations
- Centre for Veterinary Epidemiology and Risk Analysis, University College Dublin, Belfield, Dublin 4, Ireland.
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
- Forenaghts Stud, Naas, Co Kildare, Ireland.
- Centre for Veterinary Epidemiology and Risk Analysis, University College Dublin, Belfield, Dublin 4, Ireland.
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
- Newmarket Equine Hospital, Suffolk, UK.
- Lyons Research Farm, University College Dublin, Newcastle, Co. Dublin, Ireland.
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
MeSH Terms
- Abortion, Veterinary
- Aging
- Animals
- Female
- Horses / physiology
- Infertility, Female / veterinary
- Infertility, Male / veterinary
- Logistic Models
- Male
- Multivariate Analysis
- Pregnancy
- Pregnancy Rate
- Pregnancy, Animal
- Risk Factors
Citations
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