Intake, utilization, and composition of browses consumed by the Sumatran rhinoceros (Dicerorhinus sumatrensis harissoni) in captivity in Sabah, Malaysia

Abstract

AbstractThe significant threats to the fewer than 30 wild Dicerorhinus sumatrensis harrissoni, the Bornean sub‐species of the Sumatran rhinoceros, are obvious and include poaching, habitat loss, and environmental changes. Subtle effects on population survival, however, include nutritional or other diseases, which affect morbidity and reproductive success. To address these issues and focus on animals within their natural range, this feeding trial and analysis characterizes the diet fed to the only three captive D. s. harissoni in the world housed at the Sumatran Rhino Breeding Center (SRBC) in Sabah, Malaysia. The study provides an indication of the variance in nutrient composition in local browse, and a comparison with other captive feeding studies. Mean dry matter intake (DMI), comprising ∼90% native browse species, equaled 3.55% (range=2.8–4.1%) of body mass, with a dry matter digestibility averaging 82%. The mean crude protein content of native browses (n=8 spp.) averaged 11.2% (DM basis; range=5–23%, depending on plant part), with available protein measured at 7.8%. Leaves contained significantly (P<0.001) more crude protein, and less (P<0.001) fiber (neutral detergent fiber, acid detergent fiber, and lignin) than twig fractions analyzed, but animals consumed both fractions rather non‐selectively. Of minerals quantified, Na and P were potentially limiting in native browses compared to equid nutrient requirements, and Se may have been marginal. Ca, K, and Fe levels in particular were high in most native browses. Specifically, iron ranged from 45–1,400 mg/kg (mean=230 mg/kg DM), with only three preferred species containing this nutrient at <100 mg/kg. Excess dietary iron has been linked with health issues in browsing rhinos. Additionally, high levels of other minerals (for example Mn, with a mean of 382 mg/kg DM in this study), can precipitate deficiencies in crucial elements such as calcium. In view of the structural and chemical variations of the different parts of the same plants, dietary guidelines should be developed and incorporated into the basic husbandry of these animals that include increasing the number and combinations of species of browse offered daily to adjust for variance in protein, fiber, other nutritional components and food preference, to increasing the quantity of food offered per day based on desired weight gain and reproductive status. This, combined with information on the free‐ranging rhinoceros diet composition, and additional intake and digestibility trials (with concurrent serum analysis to evaluate nutritional status) should greatly assist in providing optimal diets for this highly endangered species. Zoo Biol 0:1–15, 2006. © 2006 Wiley‐Liss, Inc.