Captive Rhinos Research Articles

Gut microbiome differences between wild and captive black rhinoceros \u2013 implications for rhino health

A number of recent studies have shown the importance of the mammalian gut microbiome in host health. In the context of endangered species, a few studies have examined the relationship between the gut microbiome in wild versus captive populations due to digestive and other health issues. Unfortunately, the results seem to vary across taxa in terms of captive animals having higher, lower, or equivalent microbiome diversity relative to their wild counterparts. Here, we focus on the black rhinoceros as captive animals suffer from a number of potentially dietary related health effects. We compared gut microbiomes of wild and captive black rhinos to test for differences in taxonomic diversity (alpha and beta) and in functional diversity of the microbiome. We incorporated a more powerful metagenomic shotgun sequencing approach rather than a targeted amplification of the 16S gene for taxonomic assignment of the microbiome. Our results showed no significant differences in the alpha diversity levels between wild and captive black rhinos, but significant differences in beta diversity. We found that bacterial taxa traditionally associated with ruminant guts of domesticated animals had higher relative abundances in captive rhinos. Our metagenomic sequencing results suggest that unknown gut microbes of wild rhinos are being replaced by those found in conventional human-domesticated livestock. Wild rhinos have significantly different functional bacterial communities compared to their captive counterparts. Functional profiling results showed greater abundance of glycolysis and amino acid synthesis pathways in captive rhino microbiomes, representing an animal receiving sub-optimal nutrition with a readily available source of glucose but possibly an imbalance of necessary macro and micronutrients. Given the differences observed between wild and captive rhino gut microbiomes, we make a number of recommendations for potentially modifying captive gut microbiome to better reflect their wild counterparts and thereby hopefully improve overall rhino health in captivity.

Noise pollution may disrupt breeding for captive rhinos in urban areas

Noise pollution may disrupt breeding for captive rhinos in urban areas

Infertility in the Southern White Rhino: Is Diet the Source of the Problem?

Infertility in the Southern White Rhino: Is Diet the Source of the Problem?

Social and spatial relationships in captive southern white rhinoceros (Ceratotherium simum simum)

Although critical to the conservation of white rhinoceros, captive breeding has proven challenging because of the poor and irregular reproductive health of many captive rhinos, and social interactions may play a significant role. This research investigated the social and spatial relationships of two captive groups of southern white rhinoceros (Ceratotherium simum simum) by examining the frequency of companion changes, the number of space maintenance vocalizations made per hour by each reproductively mature female, and dominant/subordinate interactions. The observed captive rhinos did not change their companionships during the study. They exhibited space maintenance vocalizations and display greater than once per hour, particularly when feeding. Females housed with four calves on 0.033 km(2) exhibited space maintenance vocalizations more frequently (X+/-SE = 6.19+/-0.199/hr) than females housed with one calf and more space (0.06 km(2), X+/-SE = 0.55+/-0.182/hr) and females housed without calves and more space (0.65 km(2), X+/-SE = 1.90+/-0.086/hr). Wider separation of food piles and of females with young calves is suggested to reduce the interpreted spatial stress. The presence of a large number of rhinos in restricted captive space resulted in the formation of herds with dominance hierarchies that were enforced during competition for food and shade. The most subordinate rhino in each of the herds exhibited unusual behaviors such as dung-kicking and nonestrus urine squirting, and neither has ever reproduced. Suppression of subordinate rhinos might lead to social stress that could negatively impact reproductive success. Zoo Biol 26:487-502, 2007. (c) 2007 Wiley-Liss, Inc.

Mineral concentrations in serum/plasma and liver tissue of captive and free‐ranging Rhinoceros species

AbstractMineral implications in health issues of captive rhinos have received much attention lately. This study was undertaken to establish reference values for the mineral status of rhinos. Serum/plasma samples of free‐ranging black (Diceros bicornis) and white (Ceratotherium simum) rhinos and of captive black, white, Indian (Rhinoceros unicornis), and Sumatran (Dicerorhinus sumatrensis) rhinos, as well as liver tissue samples of captive black, white, and Indian rhinos were analyzed for mineral content. Circulating mineral levels of free‐ranging animals were subject to variation according to region. In free‐ranging animals, high molybdenum (Mo) values compared to horse normals were striking. Captive animals displayed even higher circulating Mo concentrations. The significance of iron (Fe) overload in captive specimens of the browsing rhinos (black and Sumatran) was confirmed. Hepatic Fe levels increased in blacks with age. Although this Fe overload is suspected to be linked with diets, the data indicate that this is not due solely to an excessive dietary Fe supply. Whereas the grazing species (white and Indian) had high liver copper (Cu) levels, the browsing species had low to marginal liver Cu concentrations. Liver concentrations of K, Mg, Co, and Mo increased with age in captive black rhinos. Additional findings include high circulating Se levels in all rhino species. Future research should be directed at investigating factors leading to high Fe levels, and at investigating Cu metabolism in captive rhinoceros species. Zoo Biol 24:51–72, 2005. © 2005 Wiley‐Liss, Inc.

Structure and Composition of Rhinoceros Horn

AbstractRhinoceros horn has been used medicinally and as a talisman in many cultures and animals are slaughtered to obtain the horn. With the dwindling populations of rhinos, and the limited number and breeding success of captive rhinos, there is a critical need to learn as much as is possible about their horns to find an adequate substitute. Examination of rhino horn was made using optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD). The structure of the horn is unusual and consists of two separate phases, one of hair-like filaments, built around a central core in circumferential layers and the other surrounding and filling in the spaces between the filaments as a matrix. Together, these two structures make up a biological composite, structurally similar to metal, ceramic or polymer based composites. The structural morphology, the dimensions of the structures, and the chemistry of the horn are discussed. Comparisons are made between horn, hoof, and hair of rhinos and hoof and hair from horses, their nearest living relatives.