Pregnancy determination in the Asian elephant (Elephas maximus): A change in the plasma progesterone to 17α hydroxyprogesterone ratio
Publication Type: |
Journal Article |
Year of Publication: |
1997 |
Authors: |
C. A. Niemuller, H. J. Shaw, J. K. Hodges |
Publication/Journal: |
Zoo Biology |
Publisher: |
A Wiley Company, Inc., Wiley Subscription Services |
Keywords: |
exotic breeding, gestagens, reproduction, wildlife |
ISBN: |
1098-2361 |
Abstract:
Abstract 10.1002/(SICI)1098-2361(1997)16:5<415::AID-ZOO4>3.3.CO;2-3 The measurement of circulating progesterone (P) is widely used to confirm and monitor pregnancy in the captive Asian elephant. Consistently elevated progesterone (P) concentrations for a minimum of 12 weeks can be used as a positive indication of pregnancy, although two instances of prolonged P secretion during the cycle have been recorded [Rübel, 1987; Olsen et al., 1994]. Previously, we demonstrated that pregnanetriol was the major urinary gestagen metabolite enabling the noninvasive monitoring of the reproductive cycle of the Asian elephant [Niemuller et al., 1993] as well as pregnancy [unpublished data]. The importance of this unusual urinary metabolite triggered an investigation into the secretion of circulating concentrations of 17α hydroxyprogesterone (17α OHP) during pregnancy and reproductive cycles, as this steroid is the only steroid precursor of pregnanetriol. Comparison of the profiles between 17α OHP and P during early pregnancy (n = 5) and nonconceptive cycles (n = 15) demonstrated a decline in 17α OHP, but not P, as early as week 3 postmating (designated as week 1) and lasting up to week 13. Otherwise, secretions of 17α OHP mimicked P concentrations throughout pregnancy and in nonconceptive cycles. Examination of the mean ratio values of 17α OHP to P demonstrated a significant drop in the ratio during weeks 2–7 of early pregnancy from ≥0.7 to <0.7 compared with the same time period in a nonconceptive cycle (P < 0.05, N = 5). A 2×2 table analysis of the 17α OHP:P ratio during weeks 2–7 indicated that the possibility of a false positive or false negative result was 3.4 and 6.5%, respectively, based on the sensitivity and specificity of the test. Overall, gestation lengths of the pregnancies completed during this study (N = 4) ranged from 91 to 98 weeks, with a mean of 93.6 ± 2.9 (SEM) weeks. A birth-to-conception interval of 47 weeks was noted in one animal. The results described in this report provide additional data on the reproductive endocrinology of the pregnant Asian elephant and also present the earliest means to date of determining pregnancy by analysis of the 17α OHP:P ratio. Zoo Biol 16:415–426, 1997. © 1997 Wiley-Liss, Inc.