Controlling interrelationships of progesterone/LH and estradiol/LH in mares

The interrelationships of progesterone, estradiol, and LH were studied in mares ( n = 9), beginning at the first ovulation (Day 0) of an interovulatory interval. An increase in mean progesterone concentrations began on Day 0 and reached maximum on Day 6, with luteolysis beginning on Day 14. A common...

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Bibliographic Details
Published in:Animal reproduction science 2006-09, Vol.95 (1), p.144-150
Main Authors: Ginther, O.J., Utt, M.D., Bergfelt, D.R., Beg, M.A.
Format: Article
Language:English
Subjects:
Animals
corpus luteum
Estradiol
Estradiol - blood
Female
hormone secretion
Horses - blood
Horses - physiology
Linear Models
luteinizing hormone
Luteinizing Hormone - blood
Luteolysis - physiology
Mares
ovulation
Ovulation - physiology
Ovulation Detection - veterinary
Progesterone
Progesterone - blood
temporal variation
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Summary:The interrelationships of progesterone, estradiol, and LH were studied in mares ( n = 9), beginning at the first ovulation (Day 0) of an interovulatory interval. An increase in mean progesterone concentrations began on Day 0 and reached maximum on Day 6, with luteolysis beginning on Day 14. A common progesterone threshold concentration of about 2 ng/ml for a negative effect on LH occurred at the beginning and end of the luteal phase. Progesterone and LH concentrations decreased at a similar rate from Day 6 until the onset of luteolysis on Day 14, consistent with a decreasing positive effect of LH on progesterone. Concentrations of LH during the increase in the ovulatory surge consisted of two linear regression segments involving a rate of 0.4 ng/ml/day for Days 14–22 and 1.8 ng/ml/day for Day 22 to 1 day after the second ovulation. The end of the first segment and beginning of the second segment was 2 days before ovulation and was the day the ovulatory estradiol surge was at a peak.
ISSN:0378-4320
1873-2232
DOI:10.1016/j.anireprosci.2005.10.008