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.

No abstract

A total of 130 silages samples (53 of maize silages and 77 of grass silages ), which were ensiled with or without silage additives, with different soil contamination levels, with different weed percentages and with or without wilting, were used to evaluate the dry matter (DM) and crude protein (CP) ruminal degradability. The ruminal degradability of the samples was calculated from the corresponding in situ degradation parameters and from the measured passage rates of the silages fed to each experimental animal. The DM and CP degradation parameters were obtained using the logistic model of Van Milgen and Baumont. The fitting of the models to the kinetics of degradation and particle passage was carried out by non-linear regression. The value of the effective degradability, considering in the rumen simultaneously an outflow compartment and a mixing-reduction compartment, were calculated in both cases from an adaptation of the general procedure proposed by Ørskov and McDonald. A NIRSystems 6500 spectrometer was used for the prediction of the DM and the CP degradation characteristics of the samples. Calibration equations were obtained by modified partial least squares regression, using reflectance spectra transformed into the second derivative. The results showed that near infrared spectroscopy is a good method for predicting the DM and CP degradation characteristics. The calibrations for effective degradability of maize and grass silages indicated a high consistency.

No abstract

No abstract

Two nineteen day rat gestation/metabolic studies were carried out with thirty female rats to investigate the influence of fresh and dried cassava containing 173 parts/106 and 92 parts/106 HCN respectively on placental thiocyanate transfer, metabolic changes in maternal and foetal tissues and their gestational performance. The cassava diets caused marked changes in the weight gain and thiocyanate concentration of the urine and serum of the gestating rats. Amniotic fluid thiocyanate was significantly increased by the fresh cassava diets (P 0.05). Rhodanese activity and fresh weights of maternal and foetal tissues were also not significantly affected by the cassava diets (P> 0.05).