Feed intake, diet utilization, and composition of browses consumed by the Sumatuan rhino (Dicerorhinus sumatrensis) in a North American Zoo

The Sumatran rhino (Dicerorhinus sumatrensis), presently indigenous to the Malay peninsula and the islands of Sumatra and Borneo, is faced with extinc tion. It is estimated that fewer than 400 individuals still exist in the wi ld. In response, concerted efforts have been made to maintain and breed thi s species in captivity, and proper diet and nutrition underlie reproduction . The present feeding trial characterizes a diet fed to three Sumatran rhin os at the Cincinnati Zoo and Botanical Garden. The diet consists of mixed a lfalfa/orchard grass hay, a variety of browses, grain pellets, produce (app les and bananas), and a vitamin E supplement. All three rhinos maintained b ody weight (614-761 kg), regular patterns of bowel movements, and fecal con sistency and composition throughout the three 5-day trials. Dry matter inta ke (DMI) ranged from 1.40 to 2.49% of body mass. Browse contributed by far the majority of nutrients to the diets in this study, from 62 to 83% of DMI . The nutrient composition of six species of subtropically grown browses (t wo from differing locations, for a total of eight browses characterized! sh owed that leaves did not differ from twigs in water or lignin content, but leaves contained higher concentrations of protein (both crude and bound) an d ash, as well as lower fiber fractions. Of the macrominerals analyzed, onl y phosphorus differed between leaves and twigs, with twigs containing signi ficantly more. No differences were seen between leaves and twigs in iron, m olybdenum, or zinc content, but leaves contained lower concentrations of co pper and higher concentrations of manganese and selenium compared with twig s from the same plants. Dry matter digestibility averaged approximately 50% . The only overt imbalances detected when comparing rhino diets with nutrie nt recommendations for domestic equids were excess calcium relative to phos phorus intake and low copper intake. These data, combined with information on native browse composition, intake, and digestibility, should greatly ass ist in providing suitable diets for this highly endangered species. Zoo Bio l 19:169-180, 2000. (C) 2000 Wiley-Liss. Inc.