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Reproduction in domestic animals = Zuchthygiene2022; 58(1); 141-145; doi: 10.1111/rda.14273

The post-ovulatory rise in progesterone is lower and the persistence of oestrous behaviour longer during the first compared with the second cycle of the breeding season in mares.

Abstract: Mares are seasonally polyoestrous breeders. Therefore, the first ovulation of the season, following winter anoestrus, is the only cycle in which mares ovulate without the presence of an old CL from the previous cycle. The objective of this study was to compare the length of oestrous behaviour, and plasma progesterone concentrations during the early post-ovulatory period between mares after the first and second ovulation of the breeding season. Overall, 38 mares and 167 oestrous periods were used in the study. From those, 11 mares were used during the first and subsequent oestrous period to measure and compare the post-ovulatory rise in progesterone concentration, whereas all the mares were used to compare the length of the post-ovulatory oestrous behaviour between the first and subsequent cycles of the breeding season. The persistence of the post-ovulatory oestrus was longer (p < .001) following the first ovulation of the year (median of 52 h) compared with the subsequent ovulations (median of 36 h for second and later ovulations groups; n = 38 mares). The progesterone concentration at any of the four 8 h-intervals analysed (28, 36, 76 and 84 h post-ovulation) was lower (p < .01) following the first versus the second ovulation of the year. By 36 h post-ovulation the progesterone concentration of mares at the second ovulation of the year had passed the threshold of 2 ng/ml (2.1 ± 0.33 ng/ml), whereas in the first cycle it was 1.2 ± 0.13 ng/ml. In conclusion, mares had lower progesterone concentrations in their peripheral circulation and longer persistence of oestrous behaviour following the first ovulation of the year compared with the second and subsequent ovulatory periods of the breeding season.
© 2022 The Authors. Reproduction in Domestic Animals published by Wiley-VCH GmbH.
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Publication Date: 2022-10-06 PubMed ID: 36177828PubMed Central: PMC10091980DOI: 10.1111/rda.14273Google Scholar: Lookup
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  • 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.

The research study investigates the difference in hormone levels and behaviours between the first and second breeding cycles in mares (female horses). There’s a lower rise in progesterone, a crucial hormone for conception, and an extended period of reproduction-related behaviour following the first ovulation compared to the second and subsequent cycles.

About the Research

  • This research was conducted to study the differences in oestrous behaviour duration and progesterone concentration levels in mares after their first and second ovulation during the breeding season.
  • Mares are seasonally polyoestrous – they have multiple oestrus cycles within a single breeding season. The study was conducted considering this aspect of mare reproduction.

Participants and Methodology

  • This study used 38 mares and evaluated 167 oestrous periods. From these mares, 11 were used for both their first and subsequent oestrous periods for measuring and comparing the post-ovulatory rise in progesterone concentration, while all of them were used to compare the duration of post-ovulatory oestrous behaviour across different cycles of the breeding season.
  • The progesterone concentrations were examined at four intervals— 28, 36, 76, and 84 hours—after ovulation in each cycle.

Findings

  • The oestrous behaviour following the first ovulation of the year persisted longer than it did after the subsequent ovulations. The median duration was 52 hours for the first ovulation and 36 hours for the subsequent ones.
  • The progesterone levels were lower after the first ovulation than the second one. After 36 hours post-ovulation, the mares reached a progesterone concentration of 2.1 ± 0.33 ng/ml during the second ovulation cycle while it was only 1.2 ± 0.13 ng/ml during the first cycle.

Conclusion

  • The study concluded that mares exhibited prolonged oestrus behaviour and lower progesterone concentrations in their blood after the first ovulation of the year compared to the second and subsequent ovulatory periods of the breeding season. Understanding these changes could be crucial for effective breeding management and strategies.

Cite This Article

APA
Newcombe JR, Wilsher S, Cuervo-Arango J. (2022). The post-ovulatory rise in progesterone is lower and the persistence of oestrous behaviour longer during the first compared with the second cycle of the breeding season in mares. Reprod Domest Anim, 58(1), 141-145. https://doi.org/10.1111/rda.14273

Publication

Reproduction in domestic animals = Zuchthygiene
ISSN: 1439-0531
NlmUniqueID: 9015668
Country: Germany
Language: English
Volume: 58
Issue: 1
Pages: 141-145

Researcher Affiliations

Newcombe, John R
  • Warren House Farm, Equine Fertility Clinic, Brownhills, UK.
Wilsher, Sandra
  • Sharjah Equine Hospital, Sharjah, United Arab Emirates.
  • The Paul Mellon Laboratory of Equine Reproduction, Newmarket, UK.
Cuervo-Arango, Juan
  • Departamento de Medicina y Cirugía Animal, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Valencia, Spain.

MeSH Terms

  • Female
  • Horses
  • Animals
  • Progesterone
  • Seasons
  • Ovulation
  • Anestrus
  • Ovulation Induction / veterinary

Conflict of Interest Statement

None of the authors have any conflict of interest to declare.

References

This article includes 14 references
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Citations

This article has been cited 2 times.
  1. Silva ESM, Newcombe JR, Cuervo-Arango J. The Effect of Treatment with Oestradiol Benzoate on Oestrus Expression and Endometrial Oedema in Anovulatory and Cyclic Mares. Animals (Basel) 2023 Mar 5;13(5).
    doi: 10.3390/ani13050938pubmed: 36899795google scholar: lookup
  2. Abdelnaby EA, Ibrahium AM, Mekkawy AM, Emam IA, Elsayed AH. Uterine and ovarian hemodynamics assessment of Camelus dromedarius with hormonal alterations and anatomical and histological architecture. Vet Res Commun 2025 Nov 13;50(1):32.
    doi: 10.1007/s11259-025-10905-7pubmed: 41225250google scholar: lookup
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