Serum concentrations of FSH, LH and progesterone during the oestrous cycle and early pregnancy in the mare.
Abstract: Heterologous radioimmunoassays were developed for equine FSH and LH. Serum concentrations were measured in twenty-three mares throughout the oestrous cycle and early pregnancy. FSH concentrations were raised fivefold by 'surges' rather than 'spiked', occurring at 10- to 11-day intervals during the oestrous cycle and early pregnancy. The late oestrous/early dioestrous surge of FSH appeared to initiate development of up to twenty follicles. The mid-dioestrous surge may be important for the further development of follicles destined to ovulate 10 to 13 days later. Levels of LH were increasing by the onset of oestrus and reached their maximum 1 to 2 days after ovulation. This rise in LH may stimuate maturation of the follicle throughout oestrus. An inverse relationship between progesterone and LH levels occurred, suggesting a negative feedback, but there was no such relationship between FSH and progesterone concentrations.
Publication Date: 1975-10-01 PubMed ID: 1060778
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
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This study developed a method to measure hormone levels in horses and utilized it to track changes during their reproductive cycle and early pregnancy, revealing significant fluctuations in hormone levels and relationships between them.
Research Methods
- This research utilized radioimmunoassays, a scientific method that uses antibodies to measure minute quantities of substances in bodily fluids such as blood. In this context, it was used to measure concentrations of three hormones: Follicle-Stimulating Hormone (FSH), Luteinizing Hormone (LH), and progesterone in the blood of twenty-three mares over their reproductive period and early pregnancy.
Finding: FSH Concentration Fluctuations
- The research found that FSH levels increased significantly in ‘surges’—approximately five times the normal concentrations—rather than in small ‘spikes’. These surges were observed at approximately 10- to 11-day intervals throughout the reproductive cycle and early pregnancy.
- The researchers theorize that the spike in FSH levels in the late oestrous (the period when a mare is sexually receptive) or early dioestrous (the period of sexual inactivity following the oestrous) stages triggered the development of up to twenty follicles (ovum-producing structures).
- They also proposed that the surge in FSH levels in the mid-dioestrous phase may contribute to further development of follicles that would release eggs 10 to 13 days later.
Observations: LH Levels and Ovulation
- In this study, researchers observed that LH levels began to increase with the onset of oestrous and reached their peak 1 to 2 days after ovulation.
- They suggested that this rise in LH levels might prompt the maturation of the follicle throughout oestrous, which is crucial to the ovulation process.
The LH-Progesterone Relationship
- A notable finding was the inverse relationship between progesterone and LH levels, indicating that as one hormone increased, the other decreased. This suggested a potential negative feedback mechanism.
- Such mechanisms are common in hormonal systems to maintain balance. In this case, high progesterone levels might inhibit further release of LH, and similarly, high LH levels might suppress further progesterone production.
No FSH-Progesterone Relationship
- In contrast to the LH-Progesterone relationship, the study found no correlation between FSH and progesterone levels, indicating that these hormones might function independently in the mare’s reproductive cycle and early pregnancy.
Cite This Article
APA
Evans MJ, Irvine CH.
(1975).
Serum concentrations of FSH, LH and progesterone during the oestrous cycle and early pregnancy in the mare.
J Reprod Fertil Suppl(23), 193-200.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Estrus
- Female
- Follicle Stimulating Hormone / blood
- Horses / blood
- Luteinizing Hormone / blood
- Pregnancy
- Progesterone / blood
- Radioimmunoassay
- Time Factors
Citations
This article has been cited 6 times.- 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.
- Cohen L, Bousfield GR, Ben-Menahem D. The recombinant equine LHβ subunit combines divergent intracellular traits of human LHβ and CGβ subunits. Theriogenology 2015 Jun;83(9):1469-76.
- Antczak DF, de Mestre AM, Wilsher S, Allen WR. The equine endometrial cup reaction: a fetomaternal signal of significance. Annu Rev Anim Biosci 2013 Jan;1:419-42.
- Adams AP, Oriol JG, Campbell RE, Oppenheim YC, Allen WR, Antczak DF. The effect of skin allografting on the equine endometrial cup reaction. Theriogenology 2007 Jul 15;68(2):237-47.
- Hedberg Y, Dalin AM, Santesson M, Kindahl H. A preliminary study on the induction of dioestrous ovulation in the mare--a possible method for inducing prolonged luteal phase. Acta Vet Scand 2006 Jul 26;48(1):12.
- Koskinen E, Lindeberg H, Kuntsi H, Katila T. Milk and serum progesterone levels in mares after ovulation. Acta Vet Scand 1990;31(4):441-4.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
