Why does a rat eat feces? - briefly
Rats practice coprophagy to reclaim nutrients, vitamins (e.g., B12) and microbial flora that were not absorbed during initial digestion. This behavior supports their nutritional balance and gut health.
Why does a rat eat feces? - in detail
Rats engage in coprophagy—consuming fecal material—to obtain nutrients that were not fully absorbed during the first passage through the gastrointestinal tract. The process allows the animal to reclaim vitamins, amino acids, and microbial metabolites produced in the large intestine.
The primary motivations are:
- Nutrient recovery – B‑vitamins (especially B12 and riboflavin) and certain amino acids are synthesized by gut microbes and concentrated in soft feces. Ingesting these pellets restores essential micronutrients.
- Microbial inoculation – Re‑ingestion introduces beneficial bacteria into the foregut, supporting digestion of complex carbohydrates and enhancing immune function.
- Energy efficiency – Small rodents have high metabolic rates; extracting additional calories from otherwise wasted material improves overall energy balance.
- Stress mitigation – In crowded or resource‑limited environments, coprophagy reduces nutritional deficits, helping maintain body condition.
Physiologically, rats produce two types of feces: hard, dry pellets expelled after the colon and soft, nutrient‑rich cecal pellets that are expelled shortly after formation. The latter are the target of re‑consumption. The cecum houses a dense microbial community that ferments fibers, generating short‑chain fatty acids and synthesizing B‑vitamins. Because the small intestine absorbs only a fraction of these compounds, the soft pellets serve as a secondary delivery system.
Research on laboratory rodents shows that preventing coprophagy—by using cages with wire mesh floors—leads to deficiencies in B‑vitamins, reduced growth rates, and impaired immune responses. Conversely, allowing natural behavior restores normal physiological parameters.
In summary, rats eat feces primarily to reclaim unabsorbed nutrients, maintain a beneficial gut microbiome, and optimize energy intake, especially under conditions where food quality or quantity is limited. This behavior is a normal, adaptive component of rodent physiology rather than an anomaly.