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Comparison of different treatments for oestrous induction in seasonally anovulatory mares.
Abstract: The aim of this study was to evaluate the effects of different treatments for induction and synchronization of oestrus and ovulation in seasonally anovulatory mares. Fifteen mares formed the control group (C), while 26 mares were randomly assigned to three treatment groups. Group T1 (n = 11) were treated with oral altrenogest (0.044 mg/kg; Regumate(®) ) during 11 days. Group T2 (n = 7) was intravaginally treated with 1.38 g of progesterone (CIDR(®) ) for 11 days. In group T3 (n = 8), mares were also treated with CIDR(®) , but only for 8 days. All mares received PGF2α 1 day after finishing the treatment. Sonographic evaluation of follicles, pre-ovulatory follicle size and ovulation time was recorded. Progesterone and leptin levels were analysed. Results show that pre-ovulatory follicles were developed after the treatment in 88.5% of mares. However, the pre-ovulatory follicle growth was dispersal, and sometimes it was detected when treatment was not finished. While in mares treated with intravaginal device, the follicle was soon detected (1.5 ± 1.2 days and 2.3 ± 2.0 days in T2 and T3 groups, respectively), in T1 group, the pre-ovulatory follicle was detected slightly later (3.9 ± 1.6 days). The interval from the end of treatment to ovulation did not show significant differences between groups (T1 = 13.1 ± 2.5 days; T2 = 11.0 ± 3.6 days; T3 = 13.8 ± 4.3 days). The pregnancy rate was 47.4%, similar to the rate observed in group C (46.7%; p > 0.05). Initial leptin concentrations were significantly higher in mares, which restart their ovarian activity after treatments, suggesting a role in the reproduction mechanisms in mares. It could be concluded that the used treatments may be effective for oestrous induction in mares during the late phase of the seasonally anovulatory period. Furthermore, they cannot synchronize oestrus, and then, it is necessary to know the reproductive status of mares when these treatments are used for oestrous synchronization.
© 2012 Blackwell Verlag GmbH.
Publication Date: 2012-11-09 PubMed ID: 23137389DOI: 10.1111/rda.12098Google 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.
- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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This research study compares different hormonal treatments used to induce estrus (the season when female mammals are sexually receptive) and ovulation in mares that do not ovulate seasonally. The study finds that these methods are effective in inducing estrus, but do not synchronize the estrus cycle, necessitating awareness of the mare’s reproductive status during treatment.
Research Approach
The aim of the research was to evaluate the effectiveness of different hormonal treatments in inducing and synchronizing estrus and ovulation in mares that do not ovulate seasonally. The strategies used to achieve this included:
- Grouping a total of 41 mares into a control and three experiment groups.
- Administration of specific hormonal treatments to each experiment group for eleven or eight days.
- Analyzing follicle, pre-ovulatory follicle size, ovulation time, and levels of progesterone and leptin using sonographic evaluation and other measuring techniques.
Experiment Groups and Treatments
The three experiment groups (T1, T2, and T3) received the following treatments:
- The T1 group was treated with an oral dose of altrenogest for eleven days.
- The T2 group was given 1.38 g of intravaginal progesterone for eleven days.
- The T3 group also received intravaginal progesterone, but only for eight days.
Findings
The findings indicated several results:
- Pre-ovulatory follicles developed in 88.5% of mares after treatment.
- Pre-ovulatory follicle growth showed variation and was occasionally detected before treatment ended.
- Proestrus (the period leading up to ovulation) was detected earlier in the mares that received intravaginal progesterone, compared to the group that received oral altrenogest.
- The time from the end of treatment to ovulation did not significantly differ among groups.
- The pregnancy rate, the primary marker of reproductive success, was comparable to the control group (46.7%).
Conclusion
Despite their effectiveness, the treatments used in the study did not synchronize estrus in mares. Therefore, when these treatments are used for synchronization, the mare’s reproductive status needs to be known. The outcome of the study also hints at a potential relationship between leptin concentrations and the re-initiation of ovarian activity, marking it as an area that requires further investigation.
Cite This Article
APA
Vizuete G, Diez E, Galisteo J, Agüera E, Aguilera-Tejero E, Perez-Marín CC.
(2012).
Comparison of different treatments for oestrous induction in seasonally anovulatory mares.
Reprod Domest Anim, 48(3), 463-469.
https://doi.org/10.1111/rda.12098 Publication
Researcher Affiliations
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, University of Cordoba, Cordoba, Spain.
MeSH Terms
- Administration, Intravaginal
- Animals
- Anovulation
- Dinoprost / administration & dosage
- Dinoprost / pharmacology
- Drug Administration Schedule
- Estrus / drug effects
- Female
- Horses / physiology
- Ovulation Induction / methods
- Ovulation Induction / veterinary
- Oxytocics / administration & dosage
- Oxytocics / pharmacology
- Pregnancy
- Pregnancy Rate
- Progesterone / administration & dosage
- Progesterone / pharmacology
- Progestins / administration & dosage
- Progestins / pharmacology
- Seasons
- Trenbolone Acetate / administration & dosage
- Trenbolone Acetate / analogs & derivatives
Citations
This article has been cited 2 times.- Bianchi CP, Bruno S, Videla Dorna I, Rodríguez E, Aba MA. Effect of short-term artificial light and transvaginal progesterone device on first ovulation in late transitional mares. J Equine Sci 2022 Apr;33(1):1-6.
- Khan IU, Khairullah AR, Khan AY, Rehman AU, Mustofa I. Strategic approaches to improve equine breeding and stud farm outcomes. Vet World 2025 Feb;18(2):311-328.
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