Effects of Differences in Fibre Composition and Maturity of Forage-Based Diets on the Microbial Ecosystem and Its Activity in Equine Caecum and Colon Digesta and Faeces.
Authors: Muhonen Sara, Sadet-Bourgeteau Sophie, Julliand Véronique
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Understanding how different forage types are broken down in the equine hindgut is crucial for optimising digestive health and performance, yet limited research directly compares the microbial activity associated with varying fibre maturity and legume inclusion. Researchers fed six fistulated geldings three iso-energetic diets over 28 days—one combining concentrate with mature grass haylage, one with early and late harvested grass haylage, and one with lucerne and mature grass haylage—then analysed microbial populations and metabolic end-products in caecal, colonic and faecal samples. Whilst total bacterial, fungal and protozoal populations remained stable across diets, the acetate-to-propionate ratio shifted significantly lower with concentrate feeding, indicating reduced fibre fermentation and increased starch metabolism despite similar short-chain fatty acid concentrations. The practical takeaway is compelling: early-harvested forage maintains sufficient digestible energy to support concentrate-free feeding strategies without compromising microbial ecosystem stability or hindgut pH regulation, potentially reducing metabolic stress and associated conditions like colic and acidosis in performance horses. This finding challenges conventional thinking around energy supplementation and suggests that forage quality—not just quantity—deserves closer attention in feeding programme design.
Read the full abstract on PubMed
Practical Takeaways
- •Early harvested forage can support adequate energy intake in forage-only diets without concentrate supplementation, potentially reducing metabolic stress from starch digestion
- •Microbial populations remain stable across different forage types and maturities, but metabolic activity shifts toward more amylolytic pathways with concentrate inclusion—consider feeding strategies to minimize this shift
- •The hindgut's strong buffering capacity provides a physiological buffer against feed pH variations, but concentrate diets still produce more acidic conditions; early-cut forage represents a middle ground for managing hindgut pH
Key Findings
- •No differences in total bacterial, fungal, or protozoal populations or cellulolytic bacteria between diets differing in fibre composition and maturity
- •Lower acetate + butyrate to propionate ratio observed with concentrate diet compared to forage-only diets, indicating higher amylolytic and lower fibrolytic activity
- •Hindgut digesta buffering capacity was 5-15 fold higher than feed buffering capacity, suggesting diminished feed buffering effects distally
- •Early harvested forage diet maintained similar energy density to concentrate-supplemented diet without negative concentrate effects