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Equine veterinary journal2007; 39(5); 438-445; doi: 10.2746/042516407x1737581

Reproductive efficiency of Flatrace and National Hunt Thoroughbred mares and stallions in England.

Abstract: Previous surveys of reproductive efficiency in British Thoroughbreds included only mares and stallions standing on studfarms in and around Newmarket. The present study was widened to compare Flatrace (FR) (Group A) and National Hunt (NH) (Group B) mares and stallions on studfarms throughout England. Objective: To assess the influences of mare type, status and age, and veterinary manipulations on reproductive efficiency parameters. To compare the inherent fertility of stallions, based on singleton and twin pregnancy rates and pregnancy loss rates, in Groups A and B Thoroughbred breeding stock. Methods: Managers of 24 FR and 9 NH public studfarms were asked to complete a questionnaire for each mated oestrous cycle shown by 2321 Group A and 1052 Group B mares throughout the 2002 mating season. Parameters such as per cycle singleton and twin pregnancy rates, and pregnancy loss rates were noted, and the success of hormone treatments to induce oestrus and ovulation assessed. The number of matings per oestrus and per pregnancy were recorded, together with the incidence and effectiveness of uterine and other veterinary treatments. The inherent fertility of 84 Group A and 43 Group B stallions in the study, as measured by the singleton and twin early pregnancy rates and the pregnancy loss rates recorded in the mares they mated, was also estimated. Results: Per cycle early pregnancy (Days 13-16) was 63.2% for Group A and 65.3% for Group B mares; and 10.3% and 13.1%, respectively, of those pregnancies were twins or triplets. Early, middle and late pregnancy loss rates were 7.2% vs. 8.0% (Days 15-42), 3.6% vs. 6.1% (Days 42-1st October) and 2.7% vs. 2.1% (October-foaling), respectively. Matings per oestrus and per early pregnancy were significantly higher in Group B vs. Group A mares. For stallions that mated > or = 30 mares, overall early pregnancy rates per cycle in mares mated ranged from 30-89% across the 2 groups. Conclusions: No major differences in reproductive efficiency were identified between FR and NH mares and stallions. Increasing mare age was the single biggest limiting factor to an otherwise high rate of fertility in well-managed English Thoroughbreds. Conclusions: This study identified factors that influence reproductive efficiency in the Thoroughbred.
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Publication Date: 2007-10-04 PubMed ID: 17910269DOI: 10.2746/042516407x1737581Google Scholar: Lookup
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  • Non-U.S. Gov't

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.

The research study investigated the reproductive efficiency of Flatrace and National Hunt Thoroughbred mares and stallions throughout England. The study concluded that there are no significant differences in reproductive efficiency between these groups, however, the main factor limiting fertility was the increasing age of mares.

Objective and Methodology

  • The primary focus of the study was to assess the influence of type, status, age of mares, and veterinary manipulations on reproductive efficiency parameters.
  • It also aimed to compare the inherent fertility of stallions based on singleton and twin pregnancy rates, and pregnancy loss rates.
  • The researchers used a questionnaire filled out by managers of 24 Flatrace (Group A) and 9 National Hunt (Group B) English studfarms, documenting each mating oestrous cycle shown by 2321 Group A and 1052 Group B mares during the 2002 mating season.
  • Parameters such as singleton and twin pregnancy rates per cycle, pregnancy loss rates, efficiency of hormone treatments inducing ovulation, matings per pregnancy and per oestrus, and incidence of uterine and other veterinary treatments were recorded.
  • The inherent fertility of 84 Group A and 43 Group B stallions was estimated based on the pregnancy loss rates and early pregnancy rates recorded in the mares they mated.

Results

  • The early pregnancy rate was slightly higher for National Hunt mares (65.3%) than for Flatrace mares (63.2%); additionally, the rate of twin or triplet pregnancies was higher in the former group (13.1% compared to 10.3% in FR mares).
  • The study noted different stages of pregnancy loss rates, with no major divergence between the Group A and B mares.
  • The number of matings per oestrus and per early pregnancy was significantly higher in Group B compared to Group A.
  • There was a wide range of early pregnancy rates (30-89%) among stallions which mated with 30 or more mares, with no significant divergence between the two groups.

Conclusions

  • The study indicates no significant differences in reproductive efficiency between Flatrace and National Hunt mares and stallions, suggesting their inherent fertility is roughly equivalent.
  • The major limiting factor identified to fertility rates in these Thoroughbreds was the increasing age of the mares, proving that age is a crucial factor in reproductive success within this species.

Cite This Article

APA
Allen WR, Brown L, Wright M, Wilsher S. (2007). Reproductive efficiency of Flatrace and National Hunt Thoroughbred mares and stallions in England. Equine Vet J, 39(5), 438-445. https://doi.org/10.2746/042516407x1737581

Publication

Equine veterinary journal
ISSN: 0425-1644
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 39
Issue: 5
Pages: 438-445

Researcher Affiliations

Allen, W R
  • University of Cambridge, Department of Veterinary Medicine Equine Fertility Unit, Mertoun Paddocks, Woodditton Road, Newmarket, Suffolk CB8 9BH, UK.
Brown, L
    Wright, M
      Wilsher, S

        MeSH Terms

        • Age Factors
        • Animals
        • Breeding
        • England
        • Estrus / physiology
        • Female
        • Fertility
        • Horses / physiology
        • Male
        • Ovulation / physiology
        • Pregnancy
        • Pregnancy Rate
        • Pregnancy, Animal / physiology
        • Pregnancy, Multiple
        • Reproduction / physiology
        • Seasons
        • Surveys and Questionnaires
        • Time Factors

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