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

BACKGROUND: It is more evident that horse health is linked to the gastrointestinal tract and microbial community structure (MCS) as affected by diet. There are many marketed feeds available to enhance nutrition for horses, however the effects of these feeds on hindgut MCS are largely unknown.

AIMS/OBJECTIVES: The aim was to test the effect of a complementary forage feed (FF) on the fermentation profile and MCS in contrasting basal diets.

METHODS: A 2×2 factorial design was used to assess the effect of basal diet, forage only (FOR) or forage/concentrate (MIX), and presence/absence of FF on fermentation parameters and MCS. An in vitro hindgut fermenter was used with each treatment being replicated thrice. Vessels were fed daily and artificial saliva continually infused. Fermentation parameters were measured from the daily production and feed bags incubated for 24 and 48 h were used for MCS analysis.

RESULTS: MIX had a lower (P<0.001) vessel pH (6.4 vs. 6.3; sem 0.043) and higher (P<0.001) total volatile fatty acid production (14.56 vs 13.64 mM/d; sem 0.798). The MCS was affected by basal diet at 24 and 48 h. An interaction (P=0.003) was observed for Proteobacteria at 24 h with values of 0.66, 0.83, 1.25 and 2.79% (sem 0.300) for FOR:FF-, FOR:FF+, MIX:FF- and MIX:FF+ respectively. There was no further change (P>0.05) in MCS when FF was included.

CONCLUSION: There were differences in fermentation profile and MCS due to different basal diets. There were no negative effects of feeding FF observed within this in vitro study.