Dataset Information

Adiposity and Reproductive Cycling Status in Zoo African Elephants.

ABSTRACT: The majority of zoo African elephants exhibit abnormal reproductive cycles, but it is unclear why. Acyclicity has been positively associated with body condition scores. The objective of this study was to measure body composition and examine the relationship between adiposity and cyclicity status, mediated by glucose, insulin, leptin, and inflammation.Body composition was assessed by deuterium dilution in 22 African elephants. Each elephant was weighed and given deuterated water orally (0.05?mL/kg), and blood was collected from the ear prior to and five times after deuterium administration. Glucose, insulin, leptin, and proinflammatory biomarker concentrations in serum were determined.Body fat percentage ranged from 5.24% to 15.97%. Fat adjusted for fat free mass (FFM) and age was not significantly associated with cyclicity status (P?=?0.332). Age was the strongest predictor of cyclicity status (P?=?0.040). Fat was correlated with weight (??=?0.455, P?=?0.044) and when adjusted for FFM with circulating glucose (??=?0.520, P?=?0.022) and showed a trend for association with leptin (unadjusted: ??=?0.384, P?=?0.095; adjusted for FFM: ??=?0.403, P?=?0.087).Deuterium dilution appears to be an available technique to measure body composition in African elephants. In this sample, fat was not associated with cyclicity status, and age may be more important to cyclicity status.

SUBMITTER: Chusyd DE

PROVIDER: S-EPMC5744898 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Adiposity and Reproductive Cycling Status in Zoo African Elephants.

Chusyd Daniella E DE Brown Janine L JL Hambly Catherine C Johnson Maria S MS Morfeld Kari K Patki Amit A Speakman John R JR Allison David B DB Nagy Tim R TR

Obesity (Silver Spring, Md.) 20180101 1

<h4>Objective</h4>The majority of zoo African elephants exhibit abnormal reproductive cycles, but it is unclear why. Acyclicity has been positively associated with body condition scores. The objective of this study was to measure body composition and examine the relationship between adiposity and cyclicity status, mediated by glucose, insulin, leptin, and inflammation.<h4>Methods</h4>Body composition was assessed by deuterium dilution in 22 African elephants. Each elephant was weighed and given ...[more]

PMID: 29265776

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Project description:BackgroundThe gut microbiome is important to immune health, metabolism, and hormone regulation. Understanding host-microbiome relationships in captive animals may lead to mediating long term health issues common in captive animals. For instance, zoo managed African elephants (Loxodonta africana) and Asian elephants (Elephas maximus) experience low reproductive rates, high body condition, and gastrointestinal (GI) issues. We leveraged an extensive collection of fecal samples and health records from the Elephant Welfare Study conducted across North American zoos in 2012 to examine the link between gut microbiota and clinical health issues, reproductive hormones, and metabolic hormones in captive elephants. We quantified gut microbiomes of 69 African and 48 Asian elephants from across 50 zoos using Illumina sequencing of the 16S rRNA bacterial gene.ResultsElephant species differed in microbiome structure, with African elephants having lower bacterial richness and dissimilar bacterial composition from Asian elephants. In both species, bacterial composition was strongly influenced by zoo facility. Bacterial richness was lower in African elephants with recent GI issues, and richness was positively correlated with metabolic hormone total triiodothyronine (total T3) in Asian elephants. We found species-specific associations between gut microbiome composition and hormones: Asian elephant gut microbiome composition was linked to total T3 and free thyroxine (free T4), while fecal glucocorticoid metabolites (FGM) were linked to African elephant gut microbiome composition. We identified many relationships between bacterial relative abundances and hormone concentrations, including Prevotella spp., Treponema spp., and Akkermansia spp.ConclusionsWe present a comprehensive assessment of relationships between the gut microbiome, host species, environment, clinical health issues, and the endocrine system in captive elephants. Our results highlight the combined significance of host species-specific regulation and environmental effects on the gut microbiome between two elephant species and across 50 zoo facilities. We provide evidence of clinical health issues, reproductive hormones, and metabolic hormones associated with the gut microbiome structure of captive elephants. Our findings establish the groundwork for future studies to investigate bacterial function or develop tools (e.g., prebiotics, probiotics, dietary manipulations) suitable for conservation and zoo management.

Project description:Long-term bio-logging has the potential to reveal how movements, and hence life-history trade-offs, vary over a lifetime. Reproductive tactics in particular may vary as individuals' trade-off current investment versus lifetime fitness. Male African savanna elephants (Loxodona africana) provide a telling example of balancing body growth with reproductive fitness due to the combination of indeterminate growth and strongly delineated periods of sexual activity (musth), which results in reproductive tactics that alter with age. Our study aims to quantify the extent to which male elephants alter their movement patterns, and hence energetic allocation, in relation to (a) reproductive state and (b) age, and (c) to determine whether musth periods can be detected directly from GPS tracking data. We used a combination of GPS tracking data and visual observations of 25 male elephants ranging in age from 20 to 52 years to examine the influence of reproductive state and age on movement. We then used a three-state hidden Markov model (HMM) to detect musth behaviour in a subset of sequential tracking data. Our results demonstrate that male elephants increased their daily mean speed and range size with age and in musth. Furthermore, non-musth speed decreased with age, presumably reflecting a shift towards energy acquisition during non-musth. Thus, despite similar speeds and marginally larger ranges between reproductive states at age 20, by age 50, males were travelling 2.0 times faster in a 3.5 times larger area in musth relative to non-musth. The distinctiveness of musth periods over age 35 meant the three-state HMM could automatically detect musth movement with high sensitivity and specificity, but could not for the younger age class. We show that male elephants increased their energetic allocation into reproduction with age as the probability of reproductive success increases. Given that older male elephants tend to be both the target of legal trophy hunting and illegal poaching, man-made interference could drive fundamental changes in elephant reproductive tactics. Bio-logging, as our study reveals, has the potential both to quantify mature elephant reproductive tactics remotely and to be used to institute proactive management strategies around the reproductive behaviour of this charismatic keystone species.

Project description:IntroductionShort post-reproductive lifespan is widespread across species, but prolonged post-reproductive life-stages of potential adaptive significance have been reported only in few mammals with extreme longevity. Long post-reproductive lifespan contradicts classical evolutionary predictions of simultaneous senescence in survival and reproduction, and raises the question of whether extreme longevity in mammals promotes such a life-history. Among terrestrial mammals, elephants share the features with great apes and humans, of having long lifespan and offspring with long dependency. However, little data exists on the frequency of post-reproductive lifespan in elephants. Here we use extensive demographic records on semi-captive Asian elephants (n = 1040) and genealogical data on pre-industrial women (n = 5336) to provide the first comparisons of age-specific reproduction, survival and post-reproductive lifespan in both of these long-lived species.ResultsWe found that fertility decreased after age 50 in elephants, but the pattern differed from a total loss of fertility in menopausal women with many elephants continuing to reproduce at least until the age of 65 years. The probability of entering a non-reproductive state increased steadily in elephants from the earliest age of reproduction until age 65, with the longer living elephants continuing to reproduce until older ages, in contrast to humans whose termination probability increased rapidly after age 35 and reached 1 at 56 years, but did not depend on longevity. Post-reproductive lifespan reached 11-17 years in elephants and 26-27 years in humans living until old age (depending on method), but whereas half of human adult lifespan (of those reproductive females surviving to the age of 5% fecundity) was spent as post-reproductive, only one eighth was in elephants. Consequently, although some elephants have long post-reproductive lifespans, relatively few individuals reach such a phase and the decline in fertility generally parallels declines in survivorship in contrast to humans with a decoupling of senescence in somatic and reproductive functions.ConclusionsOur results show that the reproductive and survival patterns of Asian elephants differ from other long-lived animals exhibiting menopause, such as humans, and extreme longevity alone does not promote the evolution of menopause or post-reproductive lifespan, adding weight to the unusual kin-selected benefits suggested to favour such traits in humans and killer whales.

Dataset Information

Adiposity and Reproductive Cycling Status in Zoo African Elephants.

Publications

Adiposity and Reproductive Cycling Status in Zoo African Elephants.

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