Research Update: Effect of Hay Type on Microbiome and Fermentation in Horses

UMN extension

The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored.

The objective of the experiment, conducted by Kansas State University, was to characterize the cecal and fecal microbiome of adult horses consuming alfalfa or smooth bromegrass hay.

Six cecally cannulated horses had unlimited access to smooth bromegrass or alfalfa hay.

A 21-day acclimation period was followed by a 24-hour collection period, where cecal and fecal samples were collected every 3 hours for analysis of pH and volatile fatty acids. Horses were then switched and fed the other hay type.  

Horses consumed a similar amount of alfalfa (2.8% bodyweight) and smooth bromegrass (2.7% bodyweight) hay.

Alfalfa hay resulted in greater volatile fatty acids concentrations compared to smooth bromegrass in both sampling locations (cecum and feces).

Because volatile fatty acids concentrations were elevated in the cecum of horses fed alfalfa, it appears that alfalfa was fermented more rapidly resulting in greater volatile fatty acid absorption and energy available to horses consuming alfalfa.

Microbial community structure within each sampling location and hay type were also different from one another.

This is the first research to document differences in pH, volatile fatty acid concentrations, and the microbiome of the cecum and feces in horses fed smooth bromegrass and alfalfa hay. 

For more information on this research, read the abstract published in the Journal of Animal Science.