An investigation into the impact of the inclusion of a commercial fiber-based feed, designed for both hydration and nutrition, on the equine hindgut microbiomes.

Overview

• This study investigated how adding a commercial fiber-based feed (designed for hydration and nutrition) influences the microbial community and fermentation activity in the horse hindgut, using different base diets.

Background

• Horse health is closely linked to the condition of the gastrointestinal tract and the structure of microbial communities found there.
• Diet plays a major role in shaping these microbial communities, especially in the hindgut where fermentation occurs.
• Many commercial horse feeds aim to enhance nutrition, but their impact on the hindgut microbial community structure (MCS) has not been well studied.

Objective

• The main goal was to evaluate the effect of a complementary forage feed (FF) on both fermentation parameters and microbial community structure in the hindgut.
• This was tested on two contrasting basic diets: a forage-only diet (FOR) and a mixed diet of forage and concentrate (MIX).

Methods

• A 2×2 factorial experimental design was used, combining:
  • Basal diet: FOR (forage only) or MIX (forage plus concentrate)
  • Inclusion or exclusion of the complementary forage feed (FF)
• An in vitro hindgut fermentation system was employed to simulate the equine hindgut environment.
• Each treatment combination was replicated three times to ensure reliability.
• Vessels in the fermenter were fed daily, and artificial saliva was constantly infused to mimic natural conditions.
• Fermentation parameters such as pH, volatile fatty acid (VFA) concentrations, and ammonia levels were measured regularly.
• Feed bags incubated for 24 and 48 hours were collected for microbial community structure (MCS) analysis.

Results

• The MIX diet resulted in a significantly lower pH (6.3) compared to the FOR diet (6.4), indicating increased fermentation acidity.
• There was a significant difference in fermentation profiles between the two basal diets, showing that diet composition influences hindgut microbial activity.
• The inclusion of the fiber feed (FF) did not have any negative impact on fermentation parameters or microbial community structure.
• In some cases, FF inclusion influenced microbial community structure, but these changes were not statistically significant, indicating a potentially neutral or mild effect.

Conclusions

• Basal diet type (forage-only versus forage plus concentrate) clearly affects the fermentation environment and microbial populations in the equine hindgut.
• The commercial fiber-based complementary forage feed tested was well tolerated in vitro and did not disrupt microbial community structure or fermentation parameters.
• This suggests such feeds can be safely included in horse diets without adverse effects on hindgut microbial health.
• Further in vivo studies would be valuable to confirm these findings under real-world feeding conditions.