The efficacy of different hCG dose rates and the effect of hCG treatment on ovarian activity: ovulation, multiple ovulation, pregnancy, multiple pregnancy, synchrony of multiple ovulation; in the mare.
Abstract: Despite the widespread use of hCG to advance ovulation in the mare there is little information on efficacy of dose rates and any contraindications of its use. This study aims to investigate the effect of dose of hCG on ovulation within 48h and the effect of hCG on: ovulation, multiple ovulation (MO), pregnancy, multiple pregnancy (MP) rates and synchrony of MO; additionally whether any seasonal effect is evident. Sequential ultrasonic scanning was used to monitor the occurrence of ovulation, within 48h of treatment, in 1291 Thoroughbred mares treated with either 750iu hCG or 1500iu hCG s.c. Ovulation rate, type (single ovulations (SO), MO, synchronous, asynchronous) and subsequent pregnancy were then monitored in 1239 Thoroughbred mares on a commercial stud over 3 years, 536 of which were treated with 750iu hCG at mating, all mares were also allocated into groups according to month of mating. No significant difference existed between the two dose levels of hCG and no significant difference existed between treated and untreated mares in overall ovulations (1.32 and 1.28 respectively), MO (31.7% and 27.7%), pregnancy (65.1% and 65.6%) or MP rates (10.8% and 11.8%). There was no significant association between month of year and pregnancy or MP rates for either treated or control mares, nor for MO for untreated mares. A significant (p<0.05) association was evident between month and MO in treated mares, MO being lowest in April (22.3%). 95.9% of treated mares multiple ovulated within 48h compared with 90.7% controls, a near significant difference. In conclusion this study demonstrates that: (i) hCG dose of 750iu s.c. is just as effective in inducing ovulation within 48h as 1500iu, (ii) 750iu hCG has no significant effect on ovulation, MO, pregnancy or MP rates; (iii) a significant (p<0.05) association exists between season and MO in hCG treated mares; (iv) a tighter synchrony (ovulation within 48h) of MO is evident in hCG treated compared with control mares (p=0.052).
Publication Date: 2007-10-23 PubMed ID: 18054451DOI: 10.1016/j.anireprosci.2007.10.005Google Scholar: Lookup
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- Journal Article
Summary
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The research conducted an investigation into the effectiveness of different dose rates of human chorionic gonadotropin (hCG) in promoting ovulation in mares and observed whether there were any negative implications of its use. The study concluded that a 750iu dose of hCG is as effective as a 1500iu dose in inducing ovulation within 48 hours, having no significant impact on rates of ovulation, multiple ovulation, pregnancy, or multiple pregnancy. A correlation between season and multiple ovulation was noted in hCG-treated mares, as well as greater synchrony of multiple ovulation.
Methodology
- The study employed sequential ultrasonic scanning to keep track of ovulation within 48 hours of hCG treatment in 1291 Thoroughbred mares, given either 750iu or 1500iu hCG subcutaneously.
- Ovulation rate, type (either single ovulations or multiple ovulations, and whether these were synchronous or asynchronous), and resulting pregnancies were then monitored in another set of 1239 Thoroughbred mares over a period of three years. Among this group, 536 mares were given 750iu hCG at the time of mating.
- The mares were grouped according to the month of mating in order to observe any possible seasonal effects.
Results
- The research findings revealed no significant difference between the two hCG dose levels of 750iu and 1500iu.
- Similarly, there was no significant difference between treated and untreated mares in overall ovulation rates, multiple ovulation rates, or rates of pregnancy or multiple pregnancy.
- No significant association was found between the month of year and the rates of pregnancy, multiple pregnancy, or multiple ovulation for either treated or control mares.
- A significant association (p<0.05) was found between the month and the rate of multiple ovulation in mares treated with hCG, with the rate being lowest in April, at 22.3%.
- A comparison between treated mares and control mares revealed that a greater proportion (95.9%) of treated mares multiple ovulated within 48 hours, in comparison to the control mares (90.7%).
Conclusion
- The study demonstrates that an hCG dose of 750iu is just as effective as a dose of 1500iu in inducing ovulation within a 48-hour window.
- The study also proves that a dose of 750iu hCG does not significantly impact rates of ovulation, multiple ovulation, pregnancy, or multiple pregnancy.
- The study shows a significant correlation between the season and the frequency of multiple ovulations in hCG-treated mares.
- Finally, a greater synchrony of multiple ovulations is observed in hCG-treated mares as compared to control mares.
Cite This Article
APA
Davies Morel MC, Newcombe JR.
(2007).
The efficacy of different hCG dose rates and the effect of hCG treatment on ovarian activity: ovulation, multiple ovulation, pregnancy, multiple pregnancy, synchrony of multiple ovulation; in the mare.
Anim Reprod Sci, 109(1-4), 189-199.
https://doi.org/10.1016/j.anireprosci.2007.10.005 Publication
Researcher Affiliations
- University of Wales, Institute of Rural Sciences, Aberystwyth, Ceredigion, UK. mid@aber.ac.uk
MeSH Terms
- Animals
- Breeding / methods
- Chorionic Gonadotropin / pharmacology
- Dose-Response Relationship, Drug
- Female
- Horses
- Litter Size / drug effects
- Litter Size / physiology
- Ovary / drug effects
- Ovary / physiology
- Ovulation / drug effects
- Ovulation / physiology
- Pregnancy
- Pregnancy, Animal / drug effects
- Pregnancy, Animal / physiology
- Pregnancy, Multiple / drug effects
- Retrospective Studies
- Seasons
- Veterinary Medicine
Citations
This article has been cited 2 times.- Piotrowska-Tomala KK, Jonczyk AW, Szóstek-Mioduchowska AZ, Żebrowska E, Ferreira-Dias G, Skarzynski DJ. The Effects of Prostaglandin E(2) Treatment on the Secretory Function of Mare Corpus Luteum Depends on the Site of Application: An in vivo Study. Front Vet Sci 2021;8:753796.
- Fonseca É, Marques CC, Pimenta J, Jorge J, Baptista MC, Gonçalves AC, Pereira RMLN. Anti-Aging Effect of Urolithin A on Bovine Oocytes In Vitro. Animals (Basel) 2021 Jul 9;11(7).
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