Fibre Composition and Maturity of Forage-Based Diets Affects the Fluid Balance, Faecal Water-Holding Capacity and Microbial Ecosystem in French Trotters.
Authors: Muhonen Sara, Julliand Véronique
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary The large intestine's capacity to retain water is critical for maintaining fluid balance during intense exercise, making forage selection a potentially underutilised management tool for racing horses. Muhonen and Julliand investigated how grass maturity and legume inclusion affected water-holding capacity, hydration status and hindgut microbiology in six French trotters offered three distinct diets over a 24-day crossover trial: mature grass haylage with concentrate (CMGH), early-harvested grass haylage with mature grass (EGH), and lucerne with mature grass (LH). Horses fed early-harvested grass haylage demonstrated markedly superior fluid dynamics—faecal water-holding capacity increased to 12.6 g H₂O/g dry faeces compared to 11.1–11.4 g on the other diets, whilst faecal water excretion dropped substantially (13.1 vs 18.8–17.6 kg daily), allowing greater urinary water conservation without altering total water balance or bodyweight. This improved hydration reserve coincided with increased bacterial populations (5.4 × 10¹¹ CFU/mL), elevated butyrate production and lower colonic pH on the early-harvested forage diet—metabolic signatures suggesting enhanced microbial fermentation of more digestible fibre. For practitioners working with performance horses, this research suggests that harvesting grass haylage at an earlier growth stage may enhance the large intestine's ability to buffer fluid demands during competition, potentially reducing dehydration risk without necessitating increased concentrate feeding or compromising bodyweight.
Read the full abstract on PubMed
Practical Takeaways
- •For racing trotters in training, early-harvested grass haylage increases the large intestine's capacity to retain fluid, providing a larger physiological reserve during competitive events without adding body weight
- •Forage maturity stage significantly impacts both microbial fermentation and water dynamics in the hindgut; early-harvest forages promote healthier bacterial populations and volatile fatty acid production
- •Consider adjusting forage harvesting timing and composition for athletic horses competing in events requiring sustained effort, as this can optimize both performance and gastrointestinal health
Key Findings
- •Early-harvested grass haylage (EGH) resulted in higher faecal water-holding capacity (12.6 g H₂O/g dry faeces) compared to concentrate-mature grass haylage and lucerne-based diets (11.1 and 11.4 g H₂O/g, p=0.014)
- •EGH diet reduced faecal water excretion (13.1 kg) while increasing urinary excretion (10.5 kg) compared to other diets, preserving intestinal fluid reserves
- •Total bacterial concentrations were significantly higher on EGH diet (5.4 × 10¹¹ CFU/mL) with increased butyrate production (3.0 mmol/L) and lower pH (6.5) indicating improved fermentation
- •Body weight was lower on EGH diet (485 kg) without compromising overall water balance, benefiting athletic performance in racing horses