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Efficacy of human chorionic gonadotrophin and gonadotrophin releasing hormone for hastening ovulation in thoroughbred mares.
Abstract: Plasma progesterone levels were measured daily to determine the accuracy of diagnosing ovulation by rectal palpation carried out every other day; 81.5 per cent mares injected with human chorionic gonadotrophin showed increases of progesterone more than 1 ng/ml by 72 h after injection compared with 65 per cent of mares injected with gonadotrophin releasing hormone (GnRH) or saline. Mating at ovulation achieved a 74 per cent pregnancy rate in mares given hCG compared with 50 per cent given GnRH and 45 per cent controls. Diagnosis of ovulation per rectum on the basis of a pit in the ovarian surface or the presence of a soft friable structure was found to be accurate in 91 per cent of cases. Diagnosis based on the presence of a firm plum-like structure or the disappearance of a previously identified follicle at a given site was 60 per cent accurate. In cases of rectal diagnosis of non-ovulation 38 per cent had actually ovulated based on a rise in progesterone more than 1 ng/ml and a further 19 per cent showed a rise in progesterone by 24 h after the diagnosis. The use of hCG may improve conception rates by synchronisation of ovulation and mating and where rectal palpation of the ovaries remains the only basis for timed mating.
Publication Date: 1986-11-01 PubMed ID: 3542528DOI: 10.1111/j.2042-3306.1986.tb03680.xGoogle 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
Summary
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The research study examines the effectiveness of hormones, specifically human chorionic gonadotrophin (hCG) and gonadotrophin releasing hormone (GnRH), in promoting ovulation among thoroughbred mares and its impact on successful pregnancy rates. Results showed that administering hCG led to increased progesterone levels, better ovulation detection, and higher pregnancy rates compared to GnRH and control groups.
Methods and Measures
- The study used plasma progesterone levels measured daily, as a key indicator for ovulation, alongside rectal palpation, a physical method for detecting ovulation.
- Two hormones, human chorionic gonadotrophin (hCG) and gonadotrophin releasing hormone (GnRH), were used in the study to test their effects on ovulation.
- A saline injection was also used for comparison.
Results
- Approximately 81.5% of mares that were given hCG exhibited a notable increase in progesterone levels 72 hours after injection.
- This compares to 65% of mares injected with either GnRH or saline.
- Mares injected with hCG at the time of ovulation showed a 74% pregnancy rate, which was significantly higher compared to the 50% rate for mares given GnRH and the 45% rate for the control group.
Ovulation Diagnosis Accuracy
- Rectal palpation was used for ovulation diagnosis, focusing on identifying certain features on the ovary’s surface.
- The study found that diagnosis of ovulation was accurate in 91% of cases when a pit in the ovarian surface or the presence of a soft friable structure was observed.
- Diagnosis accuracy dropped to 60% when it was based on the presence of a firm plum-like structure or if a previously identified follicle disappeared at a certain site.
Implications and Conclusions
- In cases where ovulation was not identified through rectal palpation, an increase in progesterone levels indicated that ovulation had taken place in 38% of these cases.
- Additionally, there was a progesterone rise in 19% of the cases 24 hours after the initial diagnosis.
- The study suggests that the use of hCG, rather than GnRH, might improve conception rates by better synchronising ovulation and mating, especially when rectal palpation is the primary means to time mating.
Cite This Article
APA
Michel TH, Rossdale PD, Cash RS.
(1986).
Efficacy of human chorionic gonadotrophin and gonadotrophin releasing hormone for hastening ovulation in thoroughbred mares.
Equine Vet J, 18(6), 438-442.
https://doi.org/10.1111/j.2042-3306.1986.tb03680.x Publication
Researcher Affiliations
MeSH Terms
- Animals
- Chorionic Gonadotropin / pharmacology
- Female
- Horses / physiology
- Humans
- Ovulation / drug effects
- Ovulation Induction / veterinary
- Pituitary Hormone-Releasing Hormones / pharmacology
- Progesterone / blood
Citations
This article has been cited 3 times.- Chang ZL, Li BX, Liu B, Yao L, Yu J, Jiang GM, Tan JH. Effects of FSH and the weather during induced ovulation and timed artificial insemination to increase jenny conception rates. Sci Rep 2019 Mar 1;9(1):3220.
- Miki W, Oniyama H, Takeda N, Kimura Y, Haneda S, Matsui M, Taya K, Nambo Y. Effects of a single use of the GnRH analog buserelin on the induction of ovulation and endocrine profiles in heavy draft mares. J Equine Sci 2016;27(4):149-156.
- Gånheim A, Gånheim A, Jöchle W. Acceleration and timing of fertile ovulation in cyclic mares with a deslorelin implant. Acta Vet Scand 1995;36(4):393-400.
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