Organic matter and macromineral digestibility in domestic rabbits (Oryctolagus cuniculus) as compared to other hindgut fermenters.
Authors: Hagen K B, Tschudin A, Liesegang A, Hatt J-M, Clauss M
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary Digestive efficiency varies considerably amongst herbivorous species, yet comparative studies are hampered by the practical challenges of conducting controlled feeding trials—meaning researchers often cobble together data from disparate sources with differing methodologies. Hagen and colleagues addressed this by conducting standardised digestibility measurements in rabbits (180 measurements across 10 different diets) and combining these with compiled literature data from guinea pigs and horses, examining how dietary crude fibre and macromineral composition affected organic matter and mineral digestibility. Whilst crude fibre consistently depressed organic matter digestibility across all species studied, horses showed notably better tolerance of high-fibre diets than rabbits or guinea pigs, suggesting fundamental differences in how equines process fibrous material. Macromineral absorption proved more complex than simple dietary concentration would suggest, with interactions between individual minerals, overall diet composition, and species-specific factors all influencing apparent digestibility—particularly for sodium, potassium, and calcium. The unexpected finding that all hindgut fermenters examined (whether coprophagous rodents or horses) demonstrated high calcium digestibility regardless of dietary level hints at a fundamental physiological adaptation linked to hindgut fermentation itself, warranting further investigation across diverse species and diet compositions.
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Practical Takeaways
- •Not applicable to equine practitioners—this study focuses on rabbits, rodents, and horses as comparative models for digestive physiology, not clinical equine practice
Key Findings
- •Significant negative relationship exists between dietary crude fibre and apparent digestibility of organic matter across hindgut fermenters
- •Horses show less depression in digestive efficiency from crude fibre compared to rabbits and guinea pigs
- •Macromineral absorption depends on multiple interactive factors including individual diet characteristics and presence of other macrominerals, not just dietary concentration
- •High calcium apparent digestibility in hindgut fermenters regardless of coprophagy or fossorial habits suggests this is a general adaptation to hindgut fermentation