Effect of Dietary Forage/Concentrate Ratio on Nutrient Digestion and Energy and Protein Metabolism in Adult Donkeys.
Authors: Liu Li-Lin, Zhou Xiao-Ling, Yang Hong-Jian, Chen Rong
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Donkeys have distinctly different metabolic requirements from horses, yet feeding research in this species remains sparse—a significant gap given their widespread use globally. Researchers in China used a crossover design with six adult female donkeys (approximately 180 kg) fed three diets varying in forage/concentrate ratio (80:20, 55:45, and 35:65) over 12 weeks, measuring total tract digestibility and nitrogen and energy balance through complete faecal and urine collection. Whilst dry matter intake remained constant across all three diets, reducing forage proportion enhanced protein digestibility but compromised fibre digestibility; critically, the high-forage diet (80:20) significantly increased nitrogen excretion in urine and reduced nitrogen retention compared to moderate and low-forage diets, whilst the low-forage diet (35:65) showed superior conversion efficiency of digestible energy to metabolizable energy. The findings suggest a practical threshold: maintaining dietary forage at no less than 55% preserves optimal nitrogen and energy utilisation in donkeys, and falling below this level substantially compromises nitrogen retention despite potential energy efficiency gains—a consideration that challenges conventional equine feeding approaches and underscores the importance of species-specific nutritional management in practice.
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Practical Takeaways
- •Maintain minimum 55% forage in donkey diets to optimize nitrogen and energy utilization; lower forage levels significantly reduce nitrogen retention
- •Donkeys fed high-forage diets (>55%) show greater overall nutrient efficiency despite lower protein digestibility, making these diets more practical for long-term feeding
- •Dietary forage level affects energy metabolism efficiency differently than in horses; donkeys require specific optimization distinct from equine feeding protocols
Key Findings
- •Decreasing forage/concentrate ratio significantly increased protein digestibility but decreased fiber digestibility in donkeys
- •Increasing forage/concentrate ratio decreased nitrogen retention by increasing urinary nitrogen excretion (p < 0.01)
- •Medium-fiber diet (55:45 F/C) showed highest nitrogen loss relative to intake
- •Lower forage/concentrate ratios linearly increased conversion efficiency of digestible energy to metabolizable energy