Significance of Branches and Leaves as Feed Components for Captive Western Lowland Gorillas

Branches and leaves are routinely provided to captive gorillas; however, their forging and antioxidant contents are not well understood. In this study, branches and leaves of various tree species provided to a family of five captive western lowland gorillas (Gorilla gorilla gorilla) the Ueno zoological gardens, Tokyo Metropolitan Government, were evaluated (Figure 2B). The branch and leaf collection status for each individual was checked for six different tree species over 4 days in July and November, 2017. Leaf and bark consumption was observed for all individuals. For each type of tree species and each plant part (i.e., leaves and barks), the concentration of the antioxidants was measured using Oxygen Radical Absorbance Capacity (ORAC) values. The antioxidant concentrations were higher in the leaves than in the bark for all tree species and the concentrations in the leaves of deciduous trees in the fall foliage season were considerably higher than those in the nonfall foliage period. In standard gorilla care at zoos, branches and leaves are regarded as bedding materials. However, the detection of antioxidants in both leaves and bark and their observed consumption by gorillas indicates that these materials should be considered as feed components from a nutritional perspective.