Ovarian Ultrasonography Correlated with Fecal Progestins and Estradiol During the Estrous Cycle and Early Pregnancy in Giraffes (Giraffa camelopardalis rothschildi)

Publication Type:
 Journal Article
Year of Publication:
 2009
Authors:
 I. Lueders, T. B. Hildebrandt, J. Pootoolal, P. Rich, C. S. Gray, C. A. Niemuller
Publication/Journal:
 Biology of Reproduction
Keywords:
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ISBN:
 0006-3363 1529-7268
Abstract:

Fecal and urinary progestin analyses have shown that giraffes nexpress a short reproductive cycle, averaging 15 days, compared
with other large ruminants. However, actual ovarian events have not been correlated with the hormonal pattern. In this study,
mature cycling female Rothschild giraffes (Giraffa camelopar-dalis rothschildi) were repeatedly examined by transrectal
ultrasonography to correlate ovarian function with changes in fecal progestin (fP4 [n c¼6]) and estradiol (fE2 [n c¼6]) and
serum progestin (n c¼2) as measured by enzyme immunoassay. Five females became pregnant and were monitored during early gestation. In this study, we discovered that hormone values for fP4 in cycling giraffes do not correlate with the classic profile of
follicular development, ovulation, and luteogenesis. The corpus luteum (CL) and the next dominant follicle were forming simultaneously. A mean6SD peak in fE2 of 254.926194.76 ng/g and subsequent ovulation occurred as early as 1 day after the fall in fP4. In pregnant giraffes, the CL reached a diameter significantly larger (mean6SD, 41.0262.70 mm;P¼0.0126) than that during the cycle (33.48 62.80 mm), while follicular
activity and fluctuating fE2 were still present. With this research, we demonstrated that the progesterone profile typically used to characterize the ovarian cycle does not correlate with luteal development in the ovaries of this species. Furthermore, we conclude that the giraffe could have evolved a short reproduc-tive cycle because of the almost parallel order of ovarian events.

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