Effects of Differences in Fibre Composition and Maturity of Forage-Based Diets on the Fluid Balance, Water-Holding Capacity and Viscosity in Equine Caecum and Colon Digesta.
Authors: Muhonen Sara, Philippeau Christelle, Julliand Véronique
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Forage fibre composition fundamentally shapes hindgut fluid dynamics and overall water balance in horses, yet the practical implications of harvest timing and legume inclusion remain poorly characterised. Muhonen and colleagues fed six fistulated horses three diets over 28 days—a concentrate-heavy late-cut grass mix, an early-cut grass haylage, and a lucerne-based ration—and directly sampled caecal and colonic digesta to measure water-holding capacity (WHC), viscosity, and systemic fluid balance. Whilst lucerne diets increased total water intake and excretion, early-harvested grass haylage produced significantly higher digesta WHC without elevating bodyweight or water turnover, suggesting superior moisture retention within the hindgut itself. Digesta viscosity showed minimal dietary variation in centrifuged samples, though individual variation warrants further investigation. For practitioners managing performance horses or those prone to impaction colic, selecting earlier-cut grass forages may offer a practical strategy to maintain optimal hindgut hydration and digesta consistency whilst avoiding the excessive fluid demands associated with legume-based rations.
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Practical Takeaways
- •Early-harvested grass haylage may benefit athletic horses by improving hindgut fluid retention without excessive weight gain, potentially supporting performance and reducing colic risk
- •Lucerne-based diets increase overall water turnover; monitor fluid intake and output carefully in horses on these diets, particularly in endurance or competition situations
- •Forage maturity has measurable effects on hindgut digesta properties; consider timing of forage harvest when formulating diets for specific performance or health goals
Key Findings
- •Diet with lucerne and late-harvested grass increased total water intake and body weight compared to grass-only diets
- •Early-harvested grass haylage diet produced higher water-holding capacity of hindgut digesta than mixed early/late grass or lucerne-based diets
- •Total water excretion (faeces and urine combined) was significantly higher on lucerne-based diet
- •Digesta viscosity showed no significant differences between diets, suggesting it may not be a primary factor affected by forage maturity or legume inclusion