24-hour secretion patterns of plasma oestradiol 17beta in pony mares in late gestation.

نویسندگان

  • L J O'Donnell
  • B R Sheerin
  • J M Hendry
  • M J Thatcher
  • W W Thatcher
  • M M LeBlanc
چکیده

The mare exhibits nocturnal uterine contractions in the last 6 days of gestation. It is hypothesized that estradiol 17beta (O17beta) may be associated with the nightly increase in uterine contractions. The 24-h secretion pattern of plasma O17beta was measured in 3 pony mares in late gestation to identify changes in release as the mare neared parturition. Blood was collected weekly at 08:00 hours beginning on day 240 and every third day from day 330 until delivery. Serial blood samples were collected from each mare every 30-min for 24-h beginning on gestation day 310 and every sixth day thereafter until parturition. Concentrations of O17beta were elevated at night with lowest concentrations occurring directly before sunset (p < 0.01). The natural log of the variance was increased at sunset (p < 0.01) and was decreased during the 6-h period immediately after sunrise. This pattern was especially evident in the 6 days that preceded parturition. The contrast between nocturnal and daytime concentrations of O17beta in the last 6 days of gestation may contribute to night-time delivery in the mare.

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عنوان ژورنال:
  • Reproduction in domestic animals = Zuchthygiene

دوره 38 3  شماره 

صفحات  -

تاریخ انتشار 2003