In recent years, we have witnessed a growing concern about the energy sources used in the horse's diet, particularly with starch.
Starch is a long carbohydrate (polysaccharide) stored in plants for energy reserve. Starch reserves in plants vary, with cereals such as oats, wheat, barley and corn, commonly used in equine nutrition, having particularly high amounts.
In horse nutrition, starch plays a caloric role in the same way as fat and fiber. Simplifying a bit, in the horse's diet we find two types of carbohydrates: structural (HCE) and non-structural (HCNE).
Structural Carbohydrates (HCE)
Some structural carbohydrates such as hemicellulose and cellulose, structural constituents of plants, play a fundamental role in the horse's diet, corresponding to its fibrous needs. Most of the HCE in the horse's diet is provided by forage (hay). The digestion of these HCE into volatile fatty acids starts in the cecum, with the help of a microbial flora residing there.
Non-structural carbohydrates (HCNE)
HCNE (starch and sugars) must undergo pre-cecal digestion and absorption (in the small intestine). In this digestive process, starch must be degraded into simpler molecules, identical to sugar, easily absorbed. Glucose in circulation can be used immediately by the cells (a process mediated by the hormone insulin), it can be mobilized for the synthesis of fat or it can be stored in the form of glycogen (in the muscles and liver).
The metabolism of HCNE assumes particular relevance in the sport horse, when subjected to anaerobic activity, and in the absence of oxygen, energy production involves the use of these glycogen reserves. Insufficient glycogen stores will result in early fatigue and limit the horse's performance.