Goodfellow's tree-kangaroos feed mostly on the leaves of the silkwood tree ("Flindersia pimenteliana"). Other foods are part of their diet when available, including different kinds of fruit, cereals, flowers and grasses. They have large stomachs that they use similar to fermentation vats, much the way the stomachs of cows and related herbivores digest food. First the food is softened in one part of their stomach, and then by passing the material back up and chewing it again, they can return it to a second part of their stomach. This is where bacteria in the stomach's various chambers, breaks down the tough fibers of leaves and grasses.