Microbiota characterization throughout the digestive tract of horses fed a high-fiber vs. a high-starch diet.
Authors: Raspa Federica, Chessa Stefania, Bergero Domenico, Sacchi Paola, Ferrocino Ilario, Cocolin Luca, Corvaglia Maria Rita, Moretti Riccardo, Cavallini Damiano, Valle Emanuela
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Using 16S rRNA sequencing on samples collected from multiple sites along the digestive tract, researchers characterized the microbiota of 19 young Bardigiano horses (mean age 14.3 months) assigned to either high-starch (HS) or high-fibre (HF) diets for 129 days. The HS diet resulted in lower microbial diversity throughout the caecum, pelvic flexure and right dorsal colon, alongside marked compositional shifts at the genus and family level across all intestinal compartments. High-starch feeding was associated with several concerning microbial patterns: increased Enterobacteriaceae in the small intestine, reduced populations of fibre-fermenting Fibrobacteraceae and Prevotellaceae in the hindgut, and elevated levels of potentially pathogenic bacteria including Streptococcus and Fusobacterium (caecum and sternal flexure respectively), as well as the acidosis-associated Succinivibrionaceae in the pelvic flexure. Conversely, horses on the HF diet maintained higher populations of beneficial short-chain fatty acid producers, notably Lachnospiraceae and Ruminococcaceae, particularly evident in faecal samples. These findings underscore the importance of fibre-based feeding programmes in maintaining a stable, diverse hindgut microbiota and highlight the dysbiotic risk—including inflammation and acidosis—posed by prolonged high-starch diets in young horses.
Read the full abstract on PubMed
Practical Takeaways
- •High-starch diets promote dysbiotic microbiota shifts associated with pathogenic and acidosis-promoting bacteria—prioritize high-fiber formulations to maintain healthy hindgut fermentation
- •Feeding high-starch concentrates increases relative abundance of inflammatory bacteria (Streptococcus, Fusobacterium); monitor horses on grain-heavy diets for colic, diarrhea, or other GI signs
- •Loss of core fiber-fermenting bacterial communities with starch feeding reduces capacity for safe forage digestion and volatile fatty acid production—fiber-based nutrition supports more resilient, protective microbiota
Key Findings
- •High-starch diet significantly reduced microbial alpha diversity in caecum, pelvic flexure, and right dorsal colon compared to high-fiber diet (FDR <0.05)
- •High-starch diet increased pathogenic Streptococcus in caecum and Fusobacterium in sternal flexure, both associated with inflammatory diseases (FDR <0.05)
- •High-starch diet increased acidosis-associated Succinivibrionaceae in pelvic flexure and rectum (FDR <0.05)
- •High-starch diet reduced beneficial fiber-fermenting bacteria (Fibrobacteraceae, Prevotellaceae, Lachnospiraceae, Ruminococcaceae) throughout hindgut (FDR <0.05)