Irregular ovarian cyclicity is associated with adrenal activity in female eastern black rhinoceros (Diceros bicornis michaeli)

Comparative analysis of gestation in three rhinoceros species (Diceros bicornis; Ceratotherium simum; Rhinoceros unicornis)

This comparative analysis evaluated endocrine profiles and gestation length data of captive pregnant black rhinoceros (Diceros bicornis), white rhinoceros (Ceratotherium simum), and greater one-horned (GOH) rhinoceros (Rhinoceros unicornis). Hormone profiles were collected over three decades as part of pregnancy diagnoses. After the third month of gestation, the luteo-placental shift in progesterone production in pregnant rhinoceroses causes a significant increase in the concentration of faecal progesterone metabolites. We defined a laboratory-specific value of 1000 ng/g faeces as a threshold for incipient feto-placental progesterone production. Using this value allowed a comparison between species and revealed significant individual differences within a species. The mean ± SEM gestation days for reaching the 1000 ng/g faeces threshold were 89.5 ± 2.9 (range 56-138 days; n = 39) in black, 96.0 ± 2.6 (58-138; n = 39) in white, and 117.8 ± 5.3 (74-173; n = 19) in GOH rhinoceroses. For the calculations of gestation length, we complemented our results from three decades of reproductive monitoring with data from the literature, resulting in about 70 values for each species. Gestation length in the black, the white and the GOH rhinoceros was 460.6 ± 1.5 (range: 436 - 486), 503.8 ± 1.3 (range: 480 - 525) and 480.5 ± 1.1 (range: 453 - 505) days, respectively. Daylight length significantly affected gestation length, while the sex of offspring had no effect. On average, pregnancies with parturitions in spring and summer were one week shorter than those in autumn and winter. Although rhinoceroses are non-seasonal breeders, most parturitions in captivity occur in autumn and winter. We also analysed preconception endocrine profiles in the white rhinoceros. Conceptions in this species occurred after oestrous cycles of approximately 35 days (n = 18), 70 days (n = 3), 15 days (n = 1), after periods of ovarian inactivity (n = 5), and during a foal heat within one month after stillbirth parturition (n = 1). In conclusion, this study provides a comprehensive overview of gestational parameters in three rhinoceros species.

Ultra-performance convergence chromatography tandem mass spectrometry analysis of adrenal and gonadal steroid hormones in southern white rhinoceros(Ceratotherium simum simum) faeces and serum

Steroid hormone analysis is routinely undertaken in the assessment of stress response and reproductive function in the management of both captive and free-ranging wildlife species. Faecal samples have become the preferred sample type for analysis as collection is non-invasive and easily assessable. These investigations are generally aimed at aiding successful translocations, enhanced survival outcomes in captivity and improvement of reproductive rate. Immunoassays are the most common approach in the analysis of hormones, particularly in the case of the southern white rhinoceros (Ceratotherium simum simum). Non-specificity, attributed to structural similarity of steroid metabolites impedes accurate evaluations which can be eliminated by chromatographic techniques which are more specific, selective and provide comprehensive analyses. This study developed and validated three methods using ultra-performance convergence chromatography tandem mass spectrometry for the assessment of classical androgens, progestogens and adrenal steroids, as well as the C11-oxy androgens and C11-oxy progestogens in serum and faeces from white rhinoceros. The limit of detection and quantification were determined for each steroid, parameters such as accuracy (<19.8 % RSD) and precision (<20.2 % RSD) were established with recovery, matrix effect, and process efficiency within acceptable limits. Subsequent analysis of serum and faecal samples from five white rhinoceros identified novel steroids for the first time in this species. In addition to the classical adrenal steroids, the following C11-oxy steroids were detected in faecal samples: 11α-hydroxydihydroprogesterone (168 ng/g), 11α-hydroxyprogesterone (125.9 ng/g), 11β-hydroxyprogesterone (210.2 ng/g) and 11-ketoandrostenedione (3.3-19.6 ng/g) with 11-deoxycortisol being the major glucocorticoid (24.2-67.3 ng/g) together with 21-deoxycortisone (40.7 ng/g) and deoxycorticosterone (7.6-14.6 ng/g). In serum samples 11β-hydroxyandrostenedione (0.35-2.34 ng/mL) and 11β-hydroxytestosterone (0.18-1.62 ng/mL) were the predominant androgens with cortisol (5.8-20.5 ng/mL), the predominant glucocorticoid, while corticosterone, 18-hydroxycorticosterone and aldosterone were also detected. These methods can be applied independently to assess either androgens, progestogens, or adrenal steroid panels or in combination to assess the cohort of gonadal and adrenal steroids in faeces and/or serum, in southern white rhinoceros as well as other wildlife species. Analysis would enable the accurate assessment of reproductive health and stress responses while also distinguishing between stress and distress thus contributing to the conservation of wildlife species.

Non-invasive assessment of fecal glucocorticoid, progesterone, and androgen metabolites and microbiome in free-ranging southern white rhinoceros (Ceratotherium simum simum) in South Africa

Increased poaching in northern South Africa has necessitated relocation of large numbers of southern white rhinoceros (Ceratotherium simum simum) to the Eastern Cape Province. The climate and grassland ecology of this province differ from that of northern South Africa which may impact the health of this species. This assessment of fecal steroid levels and microbiome in 10 free-ranging southern white rhinoceros in the Eastern Cape will provide insights into white rhinoceros physiology in this biome. Fecal steroid metabolites were analyzed using enzyme immunoassay (EIA) and ultra-performance convergence chromatography tandem mass spectrometry (UPC²-MS/MS). Fecal microbial composition was assessed via next generation sequencing. EIAs with antibodies raised against progesterone (P4; mouse monoclonal - CL425 clone), testosterone (T; rabbit polyclonal), corticosterone (B; sheep polyclonal) were utilized. Pregnant females had large quantities of fecal progesterone metabolites (FPMs) detected by CL425 EIA. Pregnant females also had native P4 and 11α-hydroxydihydroprogesterone (11αOHDHP4; 4-pregnen-11α-ol-3,20-dione) detected by UPC²-MS/MS but these concentrations were 1000-fold less than the concentrations of FPMs detected by the CL425 EIA. By contrast, non-pregnant females had FPM concentrations detected by CL425 EIA which were similar to native P4 and 11αOHDHP4 concentrations detected by UPC²-MS/MS. Mean fecal androgen metabolite (FAM) concentrations detected by the T EIA were similar between males and females. 11-ketoandrostenedione (11KA4) detected by UPC²-MS/MS was higher in females than males. However, there was no difference between males and females in the concentration of fecal glucocorticoid metabolites (FGMs) detected by the B EIA. Bacteroidia, followed by Clostridia, was the most abundant classes of fecal microbes. The unfiltered microbiome of females was more diverse than that of males. The core fecal microbiome of young rhinoceros had a higher observed species richness (Shannon diversity index, and Simpson diversity index) than that of old rhinoceros. In the alpha male, immobilization was associated with an increase in FGMs detected by 11-deoxycortisol (S) detected by UPC²-MS/MS coupled with decreased abundance of Spirochaetia. We detected substantially different FAM and FPM concentrations from those previously reported for both captive and wild white rhinoceros. Comparison of our UPC²-MS/MS and EIA results underscores the fact that most EIAs are highly cross reactive for many steroid metabolites. Our data also demonstrates a distinct effect of stress not only on FGMs but also on the fecal microbiome. This is the first non-invasive assessment of fecal steroid metabolites by UPC²-MS/MS and the fecal microbiome in wild white rhinoceros.

Effects of physiological changes and social life events on adrenal glucocorticoid activity in female zoo-housed Asian elephants (Elephas maximus)

Ensuring good health and welfare is an increasingly important consideration for conservation of endangered species and includes breeding of individuals managed under human care. Understanding how factors in the captive environment affect individual animal wellbeing can be aided by long-term monitoring of biological functioning. This study involved longitudinal assessments (4 to 28 years) of reproductive and adrenal hormones in zoo-housed female Asian elephants (Elephas maximus) (age range 4 to ~71 years) to elucidate patterns in adrenal glucocorticoid (GC) activity in association with reproductive and demographic factors, and examine individual response to major social changes. Concentrations of serum and urinary cortisol covaried more consistently with physiological changes (ovarian cycle phase, puberty, pregnancy, lactational anestrus, and age) than with social life events (births, deaths, and facility transfers). Cortisol fluctuated across the ovarian cycle with mean concentrations being higher in the follicular than in the luteal phase, and concentrations were highest in lactational anestrous compared to all other reproductive states. The elephants in this study exhibited substantial individuality in adrenal GC response to major social change, reinforcing the need to assess welfare on an individual basis and to consider factors influencing the impact of perceived stressors, such as social relationships, social support, temperament, and life history. Outcomes from this study deepen our understanding of Asian elephant physiology and highlight the importance of taking intrinsic patterns of hormone secretion into account when evaluating the impact of external factors. Finally, a better understanding of the impact of social change and resiliency in response to real and perceived stressors allows us to improve social management to enhance welfare in both captive settings and free-ranging environments.