Coprophagy in rabbits: autoingestion of hard feces.

The rabbit is a representative animal species that conducts coprophagy, i. e. the production and reingestion of soft feces. We, however, encountered a maternal rabbit eating its own hard feces. A detailed investigation was performed on coprophagy in the rabbit to elucidate whether rabbits actually reingest their own hard feces. It was found that young adult Japanese White rabbits reingested their hard, as well as soft, feces directly from the anus. It has been reported that rabbits reingest only soft feces because of their high nutritive content, but the present study demonstrates that rabbits also reingest their hard feces despite their low nutritive content. It seems possible that coprophagy may be initiated by the colonic or rectal wall expanding effects of the fecal material itself.