This gives the animal a brownish gold colour that is an effective camouflage when hiding in vegetation or on a range of soils. In some animals like the Chinchilla and the Grey Agouti Gerbil the yellow band is replaced by a white one giving a grey colour that is an effective camouflage when hiding amongst rocks. This is not the case.
Agouti only applies to the banding on the coat.
Agouti animals can have grey bellies, white bellies or even agouti bellies. For example, see the photo of the Agouti bellow, it has a light agouti belly. Agoutis are a group of South American rodents that live in forests eating the fruit, nuts and other vegetation that lies on, or falls to, the forest floor. Actually they don't succeed. Agoutis are hunted for food by the natives of South America and Agoutis have been introduced to many Caribbean islands due to their food value.