Black rhinoceros (Diceros bicornis) and domestic horse (Equus caballus) hindgut microflora demonstrate similar fermentation responses to grape seed extract supplementation in vitro.
Authors: Huntley N F, Naumann H D, Kenny A L, Kerley M S
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary Researchers compared hindgut fermentation responses in horses and black rhinoceroses to grape seed extract (GSE) supplementation, since equine nutrition models are routinely applied to captive rhinoceros management despite differences in their natural feeding strategies. Using continuous in vitro culture systems with faecal inoculum from both species, they evaluated four dietary treatments containing 0%, 1.3%, 2.7% and 4.0% GSE (dry matter basis), measuring microbial fermentation, nutrient digestibility, and the iron-binding capacity of the condensed tannins present. Increased GSE inclusion proportionally elevated dietary tannin concentration and iron-chelating ability whilst stimulating microbial growth and fermentation; critically, hindgut microflora from both species responded identically to GSE supplementation, validating the horse as a suitable fermentation model for rhinoceros in this context. GSE supplementation up to 4% did not impair hindgut nutrient digestibility or microbial viability in either species, suggesting this approach is microbiologically safe as a potential dietary strategy for managing iron overload disorder in captive black rhinoceroses. Whilst these results support continued use of equine models for hindgut fermentation studies, the authors acknowledge that foregut digestive processes and nutrient absorption may differ between species and warrant separate investigation.
Read the full abstract on PubMed
Practical Takeaways
- •Grape seed extract can be safely supplemented to horses up to 4% of dry matter without compromising hindgut fermentation, making it a viable iron-chelating dietary option
- •While this in vitro work supports using equine models for rhinoceros nutrition assessment, practitioners should recognize limitations to hindgut fermentation only and seek additional species-specific research on foregut and absorption processes
- •Tannin-rich supplements show promise for managing iron metabolism in both equine and exotic animal nutrition, but clinical efficacy studies in living animals are needed before widespread dietary recommendations
Key Findings
- •Grape seed extract (GSE) supplementation up to 4% of diet dry matter stimulated microbial growth and fermentation in both horse and black rhinoceros hindgut cultures
- •Horse and black rhinoceros hindgut microflora showed similar nutrient digestibility and fermentation responses to GSE, validating the equine model for rhinoceros fermentation studies
- •GSE supplementation proportionally increased diet condensed tannin (CT) concentration and iron-binding capacity without adversely affecting hindgut nutrient digestibility or microbial viability
- •Equine nutrition knowledge and fermentation models can be applied to black rhinoceros dietary supplementation decisions, though foregut differences between species require further investigation