THE PROBLEM with grain
We feed grain to horses for energy (from the starch they contain). But to extract this energy, horses have to be able to digest the starch. The problem is, the starch in cereal grains is protected by 5 barriers to digestion (Figure 1).
When grains are fed uncooked, only a small proportion (usually <30%) of the starch is digested in the small intestine. The rest passes to the hindgut where it is fermented by hindgut bacteria and can cause many problems including: hindgut acidosis, reduced digestion of forages, reduced appetite, behavioural issues, vitamin deficiency, colic and laminitis.
We need to break down some of the seed’s barriers to make the starch able to be digested by the horse.
EXTRUSION TO the Rescue!
Milling destroys Barriers 1 and 2. Pre-conditioning and steam extrusion softens and cooks the grain, destroying barriers 3, 4 and 5, meaning the starch from extruded grains is many times more digestible than starch from other forms of grain (Figure 2).
Figure 2. Percentage of starch digested in 15 minutes in an in vitro simulation of a horse’s small intestine for raw, micronized and extruded corn. Note that actual digestion will be proportionally higher than shown here due to a longer residence time in the small intestine compared to the 15 minutes used in this in vitro assay. It is expected that starch from extruded grain is 90%+ digested in the small intestine.
