Horses have evolved as trickle feeders, designed to be chewing or occupied by roughage for a large portion of the day.
Their digestive systems are primarily designed to digest this roughage (fibre) in the hindgut where there is a population of micro-organisms. These micro-organisms break down the roughage, in a process called fermentation, to provide a source of slow release energy. The micro-organisms also have a role in supporting the local immune system and also help to prevent overgrowth of bad (pathogenic) bacteria.
In order for these functions to be maintained there must be a balanced population of beneficial bacteria within the hind gut. However, todays horses live in a very different environment to the one they evolved for. They are often subjected to a series of lifestyle challenges that can affect the balance of micro-organisms and therefore negatively affect hindgut health.
Digestion of fibre occurs in the hindgut where the population of microflora ferment the fibre to yield volatile fatty acids to provide horses with a source of slow release energy. Volatile fatty acids absorbed from the hindgut account for 60-70% of a horse’s energy requirements.