Starch digestion in broiler chickens fed cereal diets

• Key factor affecting starch digestibility is structural characteristics of starch.
• Presence of proteins and lipids on the granule surface limit the starch digestion.
• Pelleting has variable outcomes on starch digestibility depending on grain type.
• High levels of soluble NSP in grains may not be beneficial for starch digestion.
• Whole grains maintain gizzard stimulating effect and increase starch digestibility.

Starch, comprising up to 70–80% of most cereal grains, is the primary source of energy in poultry diets. Although it is generally believed that starch is well digested by poultry, low total tract and ileal starch digestibility has been reported in some studies. The structure and composition of starch granules, their interaction with protein matrix, and their availability after feed processing play important roles in the digestion of starch. There is clear evidence that starch digestion is highly correlated with its structural location within feedstuffs and components associated with starch granule. Viscous non-starch polysaccharides and feed technology practices such as pelleting, whole grain feeding and inclusion of fibrous materials also have significant influence on starch digestibility. The aim of this review is to focus on factors affecting the digestion and absorption processes of starch in poultry. The effects of components associated with starch granule, soluble and insoluble dietary fibre, anti-nutrients and feed processing on starch digestion are also reviewed.