open access

https://hdl.handle.net/2115/70979

Relationship between bovine endometrial thickness and plasma progesterone and estradiol concentrations in natural and induced estrus

英語

Ultrasonography

2018-04

Society for Reproduction and Development（SRD）

Journal of reproduction and development

64(2)

135-143

The objective of this study was to investigate cyclical changes in endometrial thickness in relation to progesterone (P-4) and estradiol-17 beta (E-2) concentrations during natural and induced estrus in 15 cows. In the prostaglandin (PG) F-2 alpha induced estrus group, ultrasonography (USG) at 6-h intervals was used to determine endometrial thickness 48-24 h before the PGF(2 alpha), treatment until 24 h after ovulation (ovulation = Day 0). In the natural estrus group, USG was performed every 48 h from Day 3 to Days 15-18 after the first ovulation, and then every 6 h until 24 h after ovulation. Endometrial thickness was standardized using Day 13 as a reference day. Blood was collected during every USG examination and plasma P-4 and E-2 concentrations were determined. Endometrial thickness of the induced estrus group (n = 11) was greater than that of the natural estrus group (n = 9) between 60 and 12 h before ovulation (P < 0.05). In the natural estrus group, prior to an increase in endometrial thickness, a decrease in P-4 and an increase in E-2 were detected. In the induced estrus group, based on the time of ovulation, an increase in endometrial thickness was detected at the same time of a decrease in P-4 before an increase in E-2. These results suggest that decreases in P-4 concentrations may be a cue to changes in endometrial thickness, while increases in E-2 concentrations appear to sustain and/or enhance these changes.

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© 2018 by the Society for Reproduction and Development

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