Changes of faecal bacterial communities and microbial fibrolytic activity in horses aged from 6 to 30 years old.
Authors: Baraille Marylou, Buttet Marjorie, Grimm Pauline, Milojevic Vladimir, Julliand Samy, Julliand Véronique
Journal: PloS one
Summary
# Editorial Summary Declining body condition and increased disease susceptibility in horses aged 15 and over may be rooted in age-related shifts in the large intestinal microbiome, prompting researchers to characterise faecal bacterial communities across 50 healthy horses (aged 6–30 years) maintained on identical diets and living conditions. Using faecal sampling after a three-week dietary stabilisation period, the team identified significant correlations between advancing age and reduced bacterial richness and diversity, alongside a notable redistribution of beneficial and non-beneficial taxa—particularly pronounced in horses aged 21–30 years. Whilst total short-chain fatty acid concentrations remained stable, the acetate proportion declined with age whilst butyrate, valerate, and iso-valerate increased proportionally; faecal pH also decreased with age, with the most dramatic differences observed between the youngest (6–10 years) and oldest (21–30 years) cohorts. The 16–20 year age category emerged as a critical transitional period showing intermediate microbiome characteristics, suggesting an intervention window before horses develop the extreme dysbiosis potentially underlying age-related pathology. For practitioners managing older horses, these findings underscore the value of strategic dietary and probiotic interventions from mid-life onwards to preserve microbial fibre-fermenting capacity and maintain health and body condition.
Read the full abstract on PubMed
Practical Takeaways
- •Consider targeted dietary and probiotic interventions from age 16 onwards, before horses reach 21+ years when microbiome dysbiosis becomes more extreme and pathological.
- •Monitor older horses (21-30 years) more closely for digestive efficiency and nutritional status as their hindgut microbial community may be less effective at extracting nutrients from forage.
- •The 16-20 year age window represents a critical intervention opportunity to support microbiome health before irreversible changes compromise condition and disease resistance in geriatric horses.
Key Findings
- •Bacterial richness and diversity significantly decrease with age, with the most pronounced changes between 6-10 year old and 21-30 year old horses.
- •A pivotal transition period occurs at 16-20 years of age where microbiome composition and metabolic parameters become increasingly dispersed.
- •Acetate proportions decrease with age while butyrate, valerate, and iso-valerate increase, suggesting altered fibre fermentation capacity in older horses.
- •Faecal pH decreases with age despite stable total short-chain fatty acid concentrations, indicating metabolic shifts in the aging equine hindgut.