Guinea pigs:
Guinea pigs have a large cecum, and like herbivorous surgeonfish, guinea pigs are coprophagous; they eat their own feces! In addition to obtaining intestinal microbes, ingestion of feces allows animals to recover more nutrients and vitamins (2, 4). One of the closest known relatives of Epulopiscium is a bacterium called Metabacterium polyspora. M. polyspora is also a Low G+C gram-positive bacterium and is a gastrointestinal symbiont of guinea pigs. The M. polyspora life cycle takes advantage of the coprophagous nature of the guinea pig host. This bacterium produces dormant endospores that can be found in the feces of the guinea pig. Coprophagy allows Metabacterium to reenter the host gastrointestinal tract or colonize new hosts.

A fistula (a surgical opening) can be implanted in the rumen,
allowing for easy collection of ruminal contents and microbes.