Reproductive cycle length and pregnancy in the southern white rhinoceros (Ceratotherium simum simum) as determined by fecal pregnane analysis and observations of mating behavior

Abstract

Pregnancy and the reproductive cycle were monitored in 13 captive southern white rhinoceros (Ceratotherium simum simum) by measuring progesterone metabolites in fecal extracts and by observing behavior patterns. Fecal hormones were measured using a monoclonal antibody produced against 4-pregnen-11-o1-3,20-dione hemisuccinate:BSA. Several subjects exhibited flat or erratic endocrine profiles, but we found evidence for 17 reproductive cycles in five females. Mating behavior coincided with nadirs in pregnane concentrations. These cycles appeared to fall into two general categories: those of approximately 1 month in duration (Type I: X -± SEM = 35.4 ± 2.2 days; n = 10) and those lasting approximately 2 months (Type II: 65.9 ± 2.4 days; n = 7). Interluteal phase lengths were similar for the two cycle types, but Type II cycles were characterized by extended luteal phases lasting more than twice as long as Type I luteal phases. Because Type I cycles predominated in our data and because evidence suggests that some Type II cycles may be aberrant, we argue that these approximately monthly cycles represent the typical reproductive cycle for this species. Three females became pregnant during the course of the study. We were able to detect pregnancy by approximately 3 months post-breeding, as indicated by sustained pregnane concentrations markedly higher than nonpregnant luteal phase concentrations. These data help to characterize important reproductive events of this species and should be useful for captive breeding efforts for this threatened species.

Faecal Progestagen Profiles in Wild Southern White Rhinoceros (Ceratotherium simum simum)

“…This technique thus facilitates the detection of pregnancy in wild individuals in a non-invasive way, which can also be useful for surveillance strategies and the detection of foetal death during pregnancy. The mean FPM profiles in wild southern white rhinoceroses found in this study resemble those found in captive white rhinoceros individuals (Schwarzenberger et al 1998;Patton et al 1999). The number of samples collected for this study was insufficient to detect ovarian cycling patterns.…”

“…2b,c). In a previous study describing 5~-reduced pregnane profiles in captive white rhinoceroses this decline prior to parturition was not seen (Patton et al 1999). However, another study found a decline in FPM during the last two weeks of pregnancy in the captive black rhinoceros (Schwarzenberger et al 1993), although this could also be related to the specificity of the antibody used.…”

“…Literature reports the existence of two different oestrous cycle lengths in captive white rhinoceros, one with a luteal phase length of 30-35 days and the other of 65-70 days. Only the shorter cycle is believed to be fertile (Hindle et al 1992;Schwarzenberger et al 1993;Radcliffe et al 1997;Patton et al 1999;Brown et al 2001). Also, periods of acyclicity have been found in captivity with a high incidence in both young and aged females (Brown et al 2001;Hermes et al 2006).…”

“…These repeated non-fertile periods are potentially contributing to the development of a variety of reproductive pathologies (Hermes et al 2006). The length of gestation in the white rhinoceros is estimated to be 16-17 months (Patton et al 1999). Pregnancy can be diagnosed approximately 3-5 months postconception by elevated progesterone concentrations (Roth 2006).…”

“…In contrast, collecting regular blood samples from wild rhinoceroses is impractical, as the animal would need to be sedated, captured and intensively monitored by an anaesthetic team for each single blood sample, thus only opportunistic blood sample collections is justified when accompanying essential immobilization for other purposes. With the development of faecal hormone assays, it is possible to collect samples in a non-invasive way, and these methods have been used to study reproduction in captive rhinoceroses (Radcliffe et al 1997;Schwarzenberger et al 1998;Patton et al 1999;Brown et al 2001). Apart from the practical advantages, this technique also bypasses the potential negative effects of stress in the results when using invasive methods (Christensen et al 2006;Wittemyer et al 2007).…”