The effects of variety, drying procedure, fineness of grinding and dietary inclusion level on the bioavailability of Cassava (Manihot esculenta crantz) starch

The bioavailability of raw cassava starch from dried, whole roots, as affected by a number of variables, both inherent and processing‐induced, was determined in a series of feeding trials using the rat as a test animal. Apparent starch digestibility was in excess of 99% and was unaffected by cassava variety, cyanide content, drying process, fineness of grinding, dietary inclusion level (up to 50% of the diet) and age of the animal. A high level of residual cyanide (406.6 mg kg−1 dried cassava chips) reduced feed intake and weight gain. Since the floor‐drying procedure, whilst effectively reducing the cyanide to an acceptable level, was without effect on the digestibility of cassava starch, it is recommended that this process be adopted for drying high cyanide cultivars of cassava destined for the animal feed market. This will allow cassava to be incorporated in the diet at a higher inclusion level with no undesirable effects on animal performance.