Digestion coefficients achieved by the black rhinoceros (Diceros bicornis), a large browsing hindgut fermenter.
Authors: Clauss M, Castell J C, Kienzle E, Dierenfeld E S, Flach E J, Behlert O, Ortmann S, Streich W J, Hummel J, Hatt J-M
Journal: Journal of animal physiology and animal nutrition
Summary
Black rhinoceroses are specialised browsers with digestive physiology distinctly different from grazing species, yet zoo diets for this species have been designed using horses as a nutritional model—an approach this research demonstrates to be inappropriate. Researchers conducted faecal digestibility trials across eight black rhinoceroses in three zoological institutions, feeding standardised zoo rations containing varying ratios of roughage, concentrates and browse material, whilst collating comparable published data from other rhinoceros species and horses on similar diets. Black rhinoceroses achieved notably lower digestion coefficients for organic matter and crude fibre than horses fed equivalent diets, and displayed a steeper decline in digestibility as dietary fibre content increased—a response pattern significantly more pronounced than in grazing rhinoceros species. These findings suggest that current captive black rhinoceros diets are typically too concentrate-rich; shifting toward higher browse or roughage proportions would align digestibility profiles more closely with natural feeding patterns and improve nutritional matching to the animal's hindgut fermentation characteristics. For equine professionals involved in wildlife nutrition or exotic equid management, this work underscores the critical importance of species-specific digestive modelling rather than relying on domestic horse data when formulating diets for specialised browsers.
Read the full abstract on PubMed
Practical Takeaways
- •Not applicable to equine practice - this study concerns rhinoceros nutrition and digestion physiology
- •Demonstrates that large browsing hindgut fermenters have fundamentally different nutritional requirements than grazing species
- •Highlights that using equine models to predict digestibility in browsing megafauna may be inappropriate
Key Findings
- •Black rhinoceroses achieved lower digestion coefficients for organic matter and crude fiber compared to horses on similar rations
- •Browsing rhinoceros species showed steeper decrease in organic matter digestibility than grazing species with increasing dietary cell wall content
- •Endogenous losses in black rhinoceroses were within range reported for horses and Indian rhinoceroses
- •Captive black rhinoceros diets contain higher proportions of concentrates than other rhinoceros species, suggesting increased browse/roughage would improve digestive efficiency