Studies on serum oestrogen and progesterone levels during the oestrous cycle and early pregnancy in mares.
Abstract: Concentrations of progesterone and oestrogens were determined by radioimmunoassay in the peripheral blood of 22 Percheron and Breton breed mares from the 6th day of oestrus to the 150th day of pregnancy. Periodical variation patterns for the mean values of oestrone, oestradiol 17beta and total oestrogens in the cycling mares were found, with two peaks on the third day before and the 15th day after ovulation, and one depression on the 6th day of oestrus. In pregnant mares, the concentrations of oestrone and oestradiol 17beta increased rapidly (P less than 0.05) after Day 105 of gestation. Progesterone levels declined after Day 18 of the cycle in cycling mares, whereas they increased in the pregnant mares. Marked changes in the ratio of total oestrogen to progesterone concentrations were found in cycling mares, especially at oestrus, but in pregnant mares the ratio always remained below 1.00.
Publication Date: 1977-04-01 PubMed ID: 862603DOI: 10.1111/j.2042-3306.1977.tb03980.xGoogle Scholar: Lookup
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- Journal Article
Summary
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The research article explores the hormone levels of progesterone and oestrogens in Percheron and Breton breed mares during their oestrous cycle and early stages of pregnancy.
Research Method
- The researchers conducted radioimmunoassay tests on the peripheral blood of 22 Percheron and Breton breed mares. These tests took place from the 6th day of the mares’ oestrus cycle to the 150th day of their pregnancy. This method was used to measure the levels of progesterone and oestrogens in the mares’ blood.
Research Findings: Oestrogen Levels
- The research found that the mean values of oestrone, oestradiol 17beta and total oestrogens in the cycling mares varied periodically.
- There were two peak points for these hormone levels: the third day before ovulation and the 15th day after ovulation. Additionally, a dip in these levels occurred on the 6th day of oestrus.
- A significant increase in the concentrations of oestrone and oestradiol 17beta hormones was observed in pregnant mares after the 105th day of gestation.
Research Findings: Progesterone Levels
- The progesterone levels in the cycling mares decreased after the 18th day of their oestrous cycle.
- However, the levels of this hormone in pregnant mares showed an increase at some point in the study.
Research Findings: Oestrogen to Progesterone Ratio
- Marked changes were observed in the ratio of total oestrogen to progesterone concentrations in the cycling mares. These changes were especially pronounced during oestrus.
- However, in pregnant mares, this ratio consistently remained below 1.00 throughout the study period.
Conclusion
- The study provides an understanding of how the levels of progesterone and oestrogen hormones fluctuate during different stages of the oestrous cycle and early pregnancy in mares.
- This information can help equine practitioners make informed decisions about breeding, and detect potential issues in the early stages of pregnancy.
Cite This Article
APA
Sato K, Miyake M, Yoshikawa T, Kambegawa A.
(1977).
Studies on serum oestrogen and progesterone levels during the oestrous cycle and early pregnancy in mares.
Equine Vet J, 9(2), 57-60.
https://doi.org/10.1111/j.2042-3306.1977.tb03980.x Publication
Researcher Affiliations
MeSH Terms
- Animals
- Estradiol / blood
- Estrogens / blood
- Estrone / blood
- Estrus
- Female
- Horses / physiology
- Pregnancy
- Pregnancy, Animal
- Progesterone / blood
Citations
This article has been cited 2 times.- Benammar A, Derisoud E, Vialard F, Palmer E, Ayoubi JM, Poulain M, Chavatte-Palmer P. The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?. Animals (Basel) 2021 Aug 4;11(8).
- Downey BR. Regulation of the estrous cycle in domestic animals-- a review.. Can Vet J 1980 Nov;21(11):301-6.
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