Energy digestibility of giant pandas on bamboo-only and on supplemented diets.

Endangered giant pandas (Ailuropoda melanoleuca) are bears (Family Ursidae), within the order Carnivora. They specialize on an herbivorous diet of bamboo yet retain a gastrointestinal tract typical of their carnivorous ancestry. The evolutionary constraints of their digestive tract result in a low extraction efficiency from bamboo (<40% in reported studies). The goal of this study was to determine the energy digestibility of bamboo by giant pandas used in digestibility trials and through subsequent analyses with bomb calorimetry. Seven digestibility trials were conducted (three with bamboo-only diets and four with supplemental diets). Energy digestibilities ranged from 7.5-38.9% for mixed diets and 9.2-34.0% for bamboo-only diets. The bamboo-only trials summarized here represent, to our knowledge, the first empirical data available for energy digestibility on a bamboo diet for giant pandas.

Seasonal shifts in giant panda feeding behavior: relationships to bamboo plant part consumption.

The giant panda (Ailuropoda melanoleuca) is classified as a carnivore, yet subsists on a diet comprised almost exclusively of bamboo. Wild and captive giant pandas use highly selective foraging behaviors for processing and consuming bamboo. These behaviors are for the first time quantified in captive giant pandas over a 5-year period of time showing highly specific seasonal trends. Giant panda feeding behavior was recorded using live video observations of two giant pandas housed at the Memphis Zoo from November 2003 to June 2008. Leaf was the primary plant part consumed from June to December, whereas culm was consumed primarily from February to May, with both bears displaying similar seasonal shifts in plant part consumption. From May to June, leaf consumption increased significantly (P-values<0.001); from June to August, leaf consumption remained high and stable. From December to March, leaf consumption decreased significantly (P-values<0.001). Specific behaviors for bamboo leaf and culm consumption were also observed. Both bears formed wads of leaves before ingestion while feeding on leaf, but the male employed this feeding behavior more often than the female (54 and 33%, respectively). Both bears used similar culm-stripping behavior (26 and 25%), used to remove the outer layer and isolate the pith for consumption. This study indicates that unique seasonal foraging behaviors observed in wild pandas are also apparent in captive animals in relation to plant part selectivity and feeding behaviors.