The chemical composition and cyanide concentration in the foliage of four cassava cultivars (M Col 113, M Col 22, M Col 1684, CM 342-170) were evaluated at four plant ages (6, 8, 10 and 12 months). The effect on cyanide elimination of sun-drying on a concrete floor and of oven-drying at 60°C was also studied, including some observations on the tannin content of dried foliage. The proximal composition, calcium and phosphorus contents, as well as the amino acid composition of dried cassava foliage compared favourably to that of sun-cured lucerne meal. In most cases, foliage from 6-to 12-month-old plants contained 25 to 30% dry matter, and as dried foliage had 13 to 20% crude protein and 16 to 20% crude fibre. Crude protein and crude fibre were the two chemical constituents which varied the most with plant age. The average gross energy of dried cassava foliage was 4.12 kcal kg-' with a range of 3.90 to 4.35 kcal kg-'. Sun-drying eliminated more cyanide than oven-drying (82 to 94% vs 68 to 7696, respectively) and in addition, most of the cyanide in sun-dried foliage was free cyanide (62 to 77%) whereas only 24 to 36% was found as such in oven-dried foliage. Sun-dried foliage samples had consistently lower tannin content than the corresponding oven-dried samples.

No abstract

Changes that occurred during the storage of fresh cassava roots and their effect upon acceptability of the roots both for human consumption as a fresh vegetable and for animal feed purposes are reported. During storage there was a rapid accumulation of total sugars accompanied by a small decline in starch content. In those roots showing internal discolouration and deterioration the percentage of sucrose declined very dramatically. Although roots softened during storage they required a longer cooking time for human consumption. In most cases roots remained of acceptable eating quality over an eight-week period although none of the stored roots were as good as freshly harvested roots. All stored roots had a sweet flavour and frequently an uneven texture not present in fresh roots. Cassava intake by pigs was lower for stored than for freshly harvested roots: this reduction was more marked for sweet than for bitter varieties which suggests that hydrocyanic acid content is not the only factor limiting consumption, texture and organoleptic changes may also be important. Despite all the changes that occurred during storage the feeding quality of cassava meal in rat feeding trials was not noticeably affected, thus for practical purposes the preparation of cassava meal for diets for domestic animals, notably chicken and pigs, might eliminate the limitations observed in texture and eating quality of stored roots.