Guinea pig

The domestic cavy is an herbivorous animal.

An excerpt from the article 20 facts about guinea pig

Guinea pigs living in the wild, due to the poor quality of their food, may be prone to coprophagia and chew their feces during the day. They usually eat fecal pellets directly from their anus.

Newborn cavies eat their mother's feces, which allows the necessary bacterial flora to be introduced into their digestive system.