Seasonal effects on attempts to synchronize estrus and ovulation by intravaginal application of progesterone-releasing device (PRID) in mares.
Abstract: To investigate seasonal effects on the efficacy of estrus synchronization in mares, we administered a progesterone-releasing device (PRID) intravaginally to eight Haflinger mares for 11 days. In January 3 of 8 mares responded to the treatment with estrus and ovulation, in March 7 with estrus and 6 of 7 mares with ovulation, in June 6 of 7 and in October 7 of 8 mares with estrus and ovulation. Follicle distribution patterns at PRID insertion were different between January/October, March/June and June/October (P<0.05). Number of follicles decreased during PRID treatment in January, March and June (difference of number of follicles at Day 12 minus number of follicles at Day 1: -4.2+/-2.7, -0.9+/-0.9 and -4.9+/-1.5 follicles), while it increased in October (3.9+/-1.2 follicles; P<0.05). Mean progesterone concentrations were lowest in January (0.3+/-0.1 ng mL(-1)) when compared with March (3.5+/-1.8 ng mL(-1); P=0.063), June (4.4+/-1.4 ng mL(-1); P<0.05) and October (2.2+/-0.9 ng mL(-1); P<0.05). At Day 2 of PRID treatment, mean progesterone concentrations significantly increased in all mares. Except from January, mean LH concentrations decreased within one day after PRID insertion and remained at low levels during treatments in January and March. Total secretion of LH during PRID-treatment was significantly lower in January and March when compared with June and October. In the 5 of 7 mares that ovulated during PRID treatment a distinct increase of plasma LH concentrations after ovulation was detected. Administration of the progesterone releasing intravaginal device PRID combined with the PGF2alpha analogue cloprostenol was able to induce estrus and ovulation in mares at different times of the year. However, efficacy of the treatment was not satisfactory concerning effectiveness in relation to season and synchrony of intervals from removal of PRID to ovulation in mares.
Publication Date: 2005-09-01 PubMed ID: 16139879DOI: 10.1016/j.theriogenology.2005.07.013Google Scholar: Lookup
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- Journal Article
Summary
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The research investigates the seasonal impacts on the effectiveness of a progesterone-releasing device (PRID) used intravaginally to synchronize estrus and ovulation in Haflinger mares. The researchers found varying responses among the tested mares across different seasons, implicating that the effectiveness of PRID is influenced by seasonal changes.
Experiment Process and Results
- In this study, a progesterone-releasing device, PRID, was intravaginally administered to eight Haflinger mares for 11 days across different seasons. Their response in terms of estrus and ovulation was observed.
- In January, only 3 out of 8 mares showed the desired response; in March, 7 mares went into estrus and 6 achieved ovulation; in June, 6 out of 7 mares responded; and in October, 7 out of 8 mares entered estrus and ovulated.
- The researchers recorded a notable variation in the follicle distribution at the time of PRID insertion, which was different across the months (January/October, March/June, and June/October).
- The count of follicles diminished during PRID treatment in January, March, and June, while it surged in October.
Progesterone and LH Levels during Treatment
- The mean concentration of progesterone was the lowest in January compared to the levels observed in March, June, and October.
- On the second day of the PRID treatment, the concentration of progesterone increased significantly in all the mares.
- The average LH (luteinizing hormone) levels dropped within a day of PRID insertion and remained low during January and March. In contrast, the total secretion of LH during the treatment was significantly lower in January and March compared with June and October.
Efficacy of PRID Administration
- The study found that administration of PRID, in combination with the PGF2alpha analogue cloprostenol, could induce estrus and ovulation in mares across different seasons of the year.
- However, although PRID was able to induce estrus and ovulation, its effectiveness was irregular in terms of synchronizing those functions. The interval from the removal of PRID to the onset of ovulation didn’t always align, indicating the efficacy wasn’t fully satisfactory.
Cite This Article
APA
Handler J, Schönlieb S, Hoppen HO, Aurich C.
(2005).
Seasonal effects on attempts to synchronize estrus and ovulation by intravaginal application of progesterone-releasing device (PRID) in mares.
Theriogenology, 65(6), 1145-1158.
https://doi.org/10.1016/j.theriogenology.2005.07.013 Publication
Researcher Affiliations
- Clinic for Obstetrics, Gynaecology and Andrology, University of Veterinary Medicine Vienna, Veterinärplatz 1, A-1210 Vienna, Austria. Johannes.Handler@vu-wien.ac.at
MeSH Terms
- Administration, Intravaginal
- Animals
- Drug Implants / adverse effects
- Estrous Cycle
- Estrus Synchronization / methods
- Female
- Horses
- Luteinizing Hormone / blood
- Ovarian Follicle / physiology
- Ovulation Induction / methods
- Ovulation Induction / veterinary
- Progesterone / administration & dosage
- Progesterone / adverse effects
- Progesterone / blood
- Seasons
Citations
This article has been cited 3 times.- Segabinazzi LGTM, Andrade LRP Jr, Alvarenga MA, Dell'Aqua JA Jr, Canisso IF. Use of Intravaginal Progesterone-Releasing Device Results in Similar Pregnancy Rates and Losses to Long-Acting Progesterone to Synchronize Acyclic Embryo Recipient Mares. Vet Sci 2021 Sep 10;8(9).
- Okada CTC, Kaps M, Perez Quesada J, Gautier C, Aurich J, Aurich C. Diestrous Ovulations in Pregnant Mares as a Response to Low Early Postovulatory Progestogen Concentration. Animals (Basel) 2020 Nov 30;10(12).
- 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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