Effects of different levels of palm oil and sulphur in cassava-based diets

Abstract

The effects of different levels of palm oil and sulphur on the nutritive value of a cassava leaf protein diet was investigated using rats. With 40% cassava and no palm oil, the protein efficiency ratio (PER) and net protein utilisation (NPU) were very low (0·3 and 23·8, respectively) but the true digestibility was the same as that of the casein control (95·0%). With 5% palm oil there was no improvement in PER but both the NPU and biological value (BV) were increased appreciably (38·1 and 40·3, respectively). The best result was obtained with 10% palm oil, with which the PER was more than doubled (0·7) and there were similar increases in both the NPU and BV (46·6 and 48·9, respectively). Cassava at the 40% level was supplemented with various sources of sulphur—i.e. methionine, sodium thiosulphate, elemental sulphur, sodium sulphate and ferrous sulphate. With methionine, the PER, compared with the control (0·7), was more than trebled (2·2) and the NPU and BV were also significantly increased (72·6 and 83·3, respectively). Elemental sulphur gave a PER of 1·8 whilst sodium sulphate and ferrous sulphate gave 1·9. The lowest PER was obtained from sodium thiosulphate (1·1). The importance of palm oil and sulphur donors in cassava-based diets is discussed.