Cecotropes

Cecotropes are a specialized form of feces produced by animals that rely on cecal fermentation for digestion, most notably rabbits and other lagomorphs. Unlike ordinary hard fecal pellets, cecotropes are soft, mucus-coated pellets formed in the cecum and excreted with minimal water loss. They are then ingested directly from the anus by the animal.

Cecotropes contain high levels of fermentation-derived nutrients, including volatile fatty acids, B vitamins, amino acids, microbial protein, and minerals. They form when the cecum’s microbial fermentation concentrates these compounds; some absorption occurs in the small intestine, but certain vitamins and microbial products are more effectively absorbed after re-ingestion.

Re-ingestion occurs through caecotrophy, typically at night or early morning; the animal consumes the pellets directly from the anus, bypassing chewing, and passes them to the stomach and small intestine again for absorption. The mucus coating helps protect the material from stomach acids during passage.

Cecotrophy is common in domestic rabbits and other lagomorphs, and is less common or absent in many other herbivores. The behavior supports nutrient use from fibrous diets and microbial protein production. Disruptions of caecotrophy, due to illness or dental problems, can lead to reduced nutrient intake and digestive problems.