Sunlight or vitamin D-3 in the diet is also essential. Monkeys are primates, just like humans. Gorillas eat only plants in the wild, with lots of fiber and very little fat. We're just developing high-fiber biscuits they enjoy, and we've seen improved health with lower cholesterol problems. Our gorillas eat big green salads every day, with raw vegetables, very little fruit, high fiber biscuits, fresh browse from the trees, and no meat or eggs.
Youngsters also get yogurt.
The fruits they consume often have much more fiber and less water and sugar than fruit substitutes found in zoos. In Southeast Asia, they consume leaves, buds, young twigs of trees, fruits, seeds and nuts, as well as some insects, occasional bird eggs and small animals. With a bigger hindgut, they can harbor more bacteria to break down the plant cell walls for energy. Two main problems with zoo animals include obesity and diabetes. Orangutans typically eat fruits and leaves in nature, and very little animal matter.