Dietary impact on circulating glucose profiles in the white rhinoceros

Increased inflammation and decreased insulin sensitivity indicate metabolic disturbances in zoo-managed compared to free-ranging black rhinoceros (Diceros bicornis)

Black rhinoceros (rhinos) living in zoos express a host of unusual disease syndromes that are associated with increased morbidity and mortality, including hemolytic anemia, rhabdomyolysis, hepatopathy and ulcerative skin disease, hypophosphatemia and iron overload. We hypothesized that iron overload is a consequence and indicator of disturbances related to inflammation and insulin/glucose metabolism. The objectives of this study were to: (1) generate the first baseline information on biomarkers of inflammation (tumor necrosis factor alpha [TNFα], serum amyloid A [SAA]), insulin sensitivity (insulin, glucose and proxy calculations of insulin sensitivity), phosphate and iron stores (ferritin) using banked serum from free-ranging black rhinos; and (2) then compare serum biomarkers between zoo-managed (n=86 individuals) and free-ranging (n=120) animals. Enzyme immunoassays were validated for serum and then biomarker levels analyzed using mixed models while controlling for sex, age and year of sample collection. Concentrations of TNFα, SAA, insulin and insulin-to glucose ratio were higher (P<0.05) in black rhinos managed in ex situ conditions compared to free-living counterparts. Findings indicate that the captive environment is contributing to increased inflammation and decreased insulin sensitivity in this endangered species.

Irregular ovarian activity, body condition and behavioural differences are associated with reproductive success in female eastern black rhinoceros (Diceros bicornis michaeli)

Ex situ populations of endangered species such as the black rhinoceros play an important role in global conservation strategies. However, the European captive population of eastern black rhinoceros is performing sub-optimally, with growth rates and genetic viability limited by low birth rates and high reproductive skew. We investigated several intrinsic differences between parous and nulliparous females that may underlie differences in reproductive success, including ovarian cyclicity, adrenal activity, behaviour and body condition. Faecal samples were collected from 39 females (17 parous, 15 nulliparous and 7 pre-reproductive) at 11 zoological institutions, every other day for between 4months and 6years. Progestagen metabolite concentration indicated that although all non-pregnant females exhibited ovarian activity, irregular cyclicity was common. Longer cycles (>40days) were more common in nulliparous females and periods of acyclicity observed more often in females that had not bred for at least 7years. Even when endocrine data indicated clear ovarian activity, overt behavioural signs of oestrus were not always apparent, particularly among nulliparous females. Faecal glucocorticoids did not differ between parous and nulliparous females, although did differ according to individual temperament. More unpredictable temperaments were associated with higher glucocorticoids, and nulliparous females tended to be rated as more unpredictable. Finally, nulliparous females had higher body condition scores than parous females. This is the first comprehensive survey of the reproductive physiology of this European captive population, and highlights a number of intrinsic differences related to parity, which may underlie differences in reproductive success among captive female black rhinoceros.

Effect of feeding different levels of wheat roti on nutrient utilization and blood metabolite profile in semi-captive Asian elephants (Elephas maximus)

This experiment was conducted to study the effect of different levels of wheat roti (WR) on nutrient utilization and blood metabolites in Asian elephants fed roughages ad libitum. Nine (3 M, 6 F) Asian elephants (14-52 years of age, 1909-3968 kg BW) were used in an experiment based on replicated Latin square design. Animals in each group (n = 3) were assigned to one of the three dietary treatments in a manner that animals in all the three groups were exposed to all the three treatments in three different periods. Each feeding trial comprised 30 days (25 days of adaptation and 5 days collection period). The amount of WR fed to the elephants was 0.18, 0.12 and 0.06% of BW in groups I, II and III, respectively. They were allowed to forage in the nearby forests for 6 h/day and to bathe for 2 h/day. The animals had ad libitum access to cut Rohini (Mallotus philippensis) trees in their night shelter. Intake and apparent digestibility of dry matter (DM), crude protein (CP), gross energy (GE), Ca, P, Fe, Cu and Zn were measured. Feed consumption was not significantly different among the groups. Significant (p < 0.01) decrease in digestibility of DM and GE and blood glucose concentration was observed with decreased level of WR in the diet. Feeding of WR at 0.06% of BW supplied adequate amount of DE, CP, Ca, P, Fe, Cu and Zn to meet requirement for adult maintenance. Feeding of WR in excess of 0.06% of BW supplied DE in excess of requirement, increased blood glucose concentration which may cause obesity and other associated health problems. It was concluded that the amount of WR should be restricted to 0.06% of BW in the diet of captive Asian elephants.

Hematology and serum biochemistry of Sumatran rhinoceroses (Dicerorhinus sumatrensis) in a rainforest sanctuary in Way Kambas National Park, Indonesia

There is a paucity of basic biological information for the Sumatran rhinoceros (Dicerorhinus sumatrensis). This information is fundamental to husbandry and management practices for captive animals and for support of in situ conservation efforts. Serial blood samples were collected over an 8-yr period to evaluate patterns in hematology and serum biochemistry values among five Sumatran rhinoceroses housed at the Sumatran Rhino Sanctuary in Way Kambas National Park, Lampung, Indonesia. Understanding the basis for variance in analytes both within and between subjects can allow use of more sensitive subject-based reference values, and is particularly suitable for small populations of endangered animals. Both intra- and intersubject variability was computed for each analyte and the associated index of individuality was determined. Previously published cutoff points for index of individuality indicate where population-based reference intervals can be used with confidence (index > 1.4) or with caution (0.6 < index < 1.4). Interrhino variability was small for the majority of analytes, with 12 of 19 analytes having an index of individuality greater than 1.4 and none having an index of individuality less than 0.6. With the high within-individual variability of most anayltes in the Sumatran rhinoceroses at the sanctuary, subject-based reference intervals offer little advantage over standard population-based reference intervals for monitoring the health of these endangered animals. Differences were noted (but not tested for statistical significance) in serum urea, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and cholesterol between young and old rhinoceroses, and in hematocrit, AST, alanine aminotransferase (ALT), LDH, and glucose between male and female rhinoceroses. Husbandry practices, animal management, nutrition and habitat factors may also impact hematology and biochemistry results, and these relationships deserve more careful investigation. This study represents the most comprehensive hematology and serum biochemistry comparison of Sumatran rhinoceroses held in natural rainforest conditions outside a traditional zoological setting.