FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Equine Vet J / Reproductive performance of a cohort of Standardbred mares u...
Equine veterinary journal2023; 56(4); 776-785; doi: 10.1111/evj.13989

Reproductive performance of a cohort of Standardbred mares under a commercial breeding system.

Abstract: Despite being a large commercial breeding industry, there is little published data on the reproductive success of Standardbred mares. Objective: To quantify the reproductive performance of Standardbred mares under artificial breeding systems in a commercial setting and determine the incidence of early embryonic and other pre-partum losses. Methods: Retrospective cohort study. Methods: Data from four commercial farms were collected across four breeding years, and all mares were bred via artificial insemination. A total of 3995 mares contributed 7229 mare years. First-cycle pregnancy rate (FCPR) and end of season pregnancy rate (SPR) were analysed in mixed-effects logistic regression models. Time-to-conception interval was analysed in a Cox regression model. Results: The mean FCPR was 61.4% (confidence interval [CI] 60.3%-62.6%), the mean end of SPR was 84.7% (CI 83.8-85.5%), the mean live foal rate (FR) was 73.1% (CI 72.1%-74.2%). Mares located on-farm were more probable to be pregnant in terms of both FCPR (odds ratio [OR] 1.168, CI 1.018-1.340, p = 0.026) and SPR (OR 2.026, CI 1.673-2.454, p < 0.001), mares inseminated with thawed-frozen semen were less probable to be pregnant in terms of FCPR (OR 0.598, CI 0.457-0.783, p < 0.001) and SPR (OR 0.479, CI 0.354-0.647, p < 0.001) compared with insemination with fresh-extended semen. Older mares (14 years and older) were less probable to be pregnant in terms of FCPR (OR 0.795, CI 0.688-0.919, p = 0.002) and SPR (0.435, CI 0.352-0.538, p < 0.001) compared with young mares (3- to 8-year old). Conclusions: Retrospective data relied on accurate record keeping of stud farms and no mare-treatment or ovulation induction records were available. Live FRs relied mostly on annual foaling returns so fetal/foal deaths may be underrepresented. Conclusions: This study provides substantial baseline data on reproductive performance for Standardbred mares managed under a commercial artificial breeding system.
© 2023 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
Get Full Text
Publication Date: 2023-08-09 PubMed ID: 37559421DOI: 10.1111/evj.13989Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigated the reproductive performance of Standardbred mares in commercial artificial breeding systems. The study presented data on the pregnancy and live foal rates, influence of mare age, location, and type of semen used, and highlighted potential gaps in record keeping.

Background

  • The Standardbred horse breeding industry lacks published data on reproductive success, making this study pertinent. The researchers aimed to quantify reproductive performances, particularly under artificial breeding systems, and to measure the rate of early embryonic and pre-partum losses.

Methods

  • This study was a retrospective cohort analysis using data accumulated over four breeding seasons from four commercial farms. All mares were bred via artificial insemination, which allowed for a large sample size of 3995 mares, contributing 7229 mare years.
  • Key performance indicators examined were the first-cycle pregnancy rate (FCPR), the end of the season pregnancy rate (SPR), live foal rate (FR), and the time-to-conception interval. Various statistical models were used for in-depth analysis.

Results

  • The overall FCPR was 61.4%, the SPR was 84.7%, and the live FR was 73.1%. The study found some factors significantly affect these rates.
  • Mares residing on the farm had higher pregnancy rates in terms of FCPR and SPR as compared to those located elsewhere.
  • Mares inseminated with thawed-frozen semen had lower FCPR and SPR compared to mares inseminated with fresh-extended semen.
  • Older mares (14 years and older) had lower FCPR and SPR compared to younger mares (3 to 8 years old).

Conclusions and Limitations

  • The accuracy of the findings relies heavily on the stud farms’ record-keeping since no mare-treatment or ovulation induction records were available, a potential limitation.
  • Also, live foal rates heavily relied on annual foaling returns, implying potential underrepresentation of fetal or foal deaths.
  • Despite the limitations, this research offers substantial baseline data on the reproductive performance of Standardbred mares under commercial artificial breeding systems. Advancements in the field could also benefit from the insights and trends identified through this study.

Cite This Article

APA
Tanner JC, Barrell GK. (2023). Reproductive performance of a cohort of Standardbred mares under a commercial breeding system. Equine Vet J, 56(4), 776-785. https://doi.org/10.1111/evj.13989

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 56
Issue: 4
Pages: 776-785

Researcher Affiliations

Tanner, Jasmine C
  • Department of Agricultural Sciences, Faculty of Agriculture and Life Sciences, Lincoln University, Christchurch, New Zealand.
Barrell, Graham K
  • Department of Agricultural Sciences, Faculty of Agriculture and Life Sciences, Lincoln University, Christchurch, New Zealand.

MeSH Terms

  • Animals
  • Horses / physiology
  • Pregnancy
  • Female
  • Retrospective Studies
  • Breeding
  • Insemination, Artificial / veterinary
  • Reproduction / physiology
  • Cohort Studies
  • Pregnancy Rate

Grant Funding

  • New Zealand Equine Research Foundation

References

This article includes 32 references
  1. Nath LC, Anderson GA, McKinnon AO. Reproductive efficiency of Thoroughbred and Standardbred horses in north‐east Victoria.. Aust Vet J 2010;88:169–175.
  2. Katila T, Reilas T, Nivola K, Peltonen T, Virtala AM. A 15‐year survey of reproductive efficiency of Standardbred and Finnhorse trotters in Finland—descriptive results.. Acta Vet Scand 2010;52:40.
  3. Morris LHA, Allen WR. Reproductive efficiency of intensively managed Thoroughbred mares in Newmarket.. Equine Vet J 2002;34:51–60.
  4. Allen WR, Brown L, Wright M, Wilsher S. Reproductive efficiency of Flatrace and National Hunt Thoroughbred mares and stallions in England.. Equine Vet J 2007;39:438–445.
  5. Lane EA, Bijnen MLJ, Osborne M, More SJ, Henderson ISF, Duffy P. Key factors affecting reproductive success of Thoroughbred mares and stallions on a commercial stud farm.. Reprod Domest Anim 2016;51:181–187.
  6. Bosh KA, Powell D, Shelton B, Zent W. Reproductive performance measures among Thoroughbred mares in central Kentucky, during the 2004 mating season.. Equine Vet J 2009;41:883–888.
  7. Bosh K, Powell D, Neibergs J, Shelton B, Zent W. Impact of reproductive efficiency over time and mare financial value on economic returns among Thoroughbred mares in central Kentucky.. Equine Vet J 2009;41:889–894.
  8. Bruck I, Anderson GA, Hyland JH. Reproductive performance of Thoroughbred mares on six commercial stud farms.. Aust Vet J 1993;70:299–303.
  9. Hanlon DW, Stevenson M, Evans MJ, Firth EC. Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 1. Descriptive analysis.. N Z Vet J 2012;60:329–334.
  10. Hanlon DW, Stevenson M, Evans MJ, Firth EC. Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 2. Multivariable analyses and sources of variation at the mare, stallion and stud farm level.. N Z Vet J 2012;60:335–343.
  11. Hanlon D, Firth E. The reproductive performance of Thoroughbred mares treated with intravaginal progesterone at the start of the breeding season.. Theriogenology 2012;77:952–958.
  12. Rogers CW, Gee EK, Vermeij E. Retrospective examination of the breeding efficiency of the New Zealand Thoroughbred and Standardbred.. Proc N Z Soc Anim Prod 2009;69:126–131.
  13. Hemberg E, Lundeheim N, Einarsso S. Reproductive performance of Thoroughbred mares in Sweden.. Reprod Dom Anim 2004;39:81–85.
  14. Gee EK, Rogers CW, Bolwell CF. Commercial equine breeding in New Zealand. 1. Reproduction and breeding.. Anim Prod Sci 2020;60:2145–2154.
  15. Ginther OJ. Reproductive biology of the mare: basic and applied aspects.. 2nd ed. Equiservices: Cross Plains; 1992.
  16. Fennessy PF. An overview of the New Zealand Thoroughbred industry.. Proc N Z Soc Anim Prod 2010;70:137–139.
  17. Heckenbichler S, Deichsel K, Peters P, Aurich C. Quality and fertility of cooled‐shipped stallion semen at the time of insemination.. Theriogenology 2011;75:849–856.
  18. Taylor TB. Artificial breeding of horses.. New Zealand: New Zealand Equine Research Foundation; 2008. p. 1–38.
  19. Anonymous. Harness Racing New Zealand regulations.. New Zealand: Harness Racing New Zealand; 2021. p. 1–133.
  20. Dohoo I, Martin W, Stryhn H. Logistic regression.. In: Dohoo I, Martin W, Stryhn H, editors. Veterinary epidemiologic research. Charlottetown, Prince Edward Island, Canada: AVC Inc; 2003. p. 360–361.
  21. Dohoo I, Martin W, Stryhn H. Modelling survival data.. In: Dohoo I, Martin W, Stryhn H, editors. Veterinary epidemiologic research. Charlottetown, Prince Edward Island, Canada: AVC Inc; 2003.
  22. Haadem CS, Nødtvedt A, Farstad W, Thomassen R. A retrospective cohort study on fertility in the Norwegian Coldblooded trotter after artificial insemination with cooled, shipped versus fresh extended semen.. Acta Vet Scand 2015;57:77.
  23. Ball BA, Little TV, Hillman RB, Woods GL. Pregnancy rates at days 2 and 14 and estimated embryonic loss rates prior to day 14 in normal and subfertile mares.. Theriogenology 1986;26:611–619.
  24. Scoggin CF. Not just a number: effect of age on fertility, pregnancy and offspring vigour in Thoroughbred brood‐mares.. Reprod Fertil Dev 2015;27:872–879.
  25. LeBlanc MM, Causey RC. Clinical and subclinical endometritis in the mare: both threats to fertility.. Reprod Dom Anim 2009;44:10–22.
  26. Squires EL, Barbacini S, Matthews P, Byers W, Schwenzer K, Steiner J. Retrospective study of factors affecting fertility of fresh, cooled and frozen semen.. Equine Vet Educ 2006;18:96–99.
  27. Langlois B, Blouin C. Statistical analysis of some factors affecting the number of horse births in France.. Reprod Nutr Dev 2004;44(6):583–595.
    doi: 10.1051/rnd:2004055google scholar: lookup
  28. Vidament M, Dupere AM, Julienne P, Evain A, Noue P, Palmer E. Equine frozen semen: Freezability and fertility field results.. Theriogenology 1997;48(6):907–917.
    doi: 10.1016/s0093-691x(97)00319-1google scholar: lookup
  29. Loy RG. Charateristics of postpartum reproduction in mares.. Vet Clin North Am Large Anim Pract 1980;2:345–360.
  30. Dicken M, Gee EK, Rogers CW, Mayhew IG. Gestation length and occurrence of daytime foaling of Standardbred mares on two stud farms in New Zealand.. N Z Vet J 2012;60:42–46.
  31. Evans MJ. What is “normal” foaling?. Found Bull 2010;16:2.
  32. Davies Morel MCG, Newcombe JR, Holland SJ. Factors affecting gestation length in the Thoroughbred mare.. Anim Reprod Sci 2002;74:175–185.
Subscribe to our newsletter
Join 99,357 horse owners like you who receive our email updates on horse health and nutrition.