The use of dried sugar cane fractions as the principal energy source in sheep rations

Abstract

A method of drying and then separating sugar cane stalks into three fractions is described. The three fractions, termed F1, F2 and F3, contained naturally occurring soluble sugars plus parenchymal cells (F1), sugars plus parenchymal cells and more fibrous tissues (F2) and even less soluble sugars and more fibrous rind tissues (F3). In Experiment 1, the three cane fractions were fed, with suitable supplements, to sheep to determine their metabolizable energy contents which were found to be 9.1, 8.9 and 8.7 MJ kg −1 DM, respectively. In the second experiment the total food intakes and live weight gains of lambs fed F1 with and without supplements of NaHCO 3, lucerne chaff or oaten chaff were determined; F2 and F3 were fed with and without lucerne chaff. The lambs fed the F1 diet supplemented with oaten chaff performed slightly better than other supplemented groups (live weight gain 99 g per head per day). Weight gains of the lambs fed the F2-based diets with and without the lucerne chaff supplement were 65 and 34 g per head per day, respectively; both groups of lambs fed the F3-based diets lost weight. The third experiment examined the effect on food intake and live weight gain of treating the cane fractions (F1 and F2 only) with NaOH or pelleting the F1-based diets. Both treatments increased intake and rate of live weight gain, but the effects were not additive; NaOH treatment of the F1 diet resulted in an increase in intake from 35.1 to 41.3 g kg −1 W day −1, whereas the intake of the pelleted F1 diet was 45.0 g kg −1 W day −1. The corresponding rates of live weight gain were 110, 148 and 188 g per head per day. Adding rice polishings or cracked white rice to the F1 diets had a positive, but non-significant effect on animal performance. Lambs fed an NaOH-treated F2-based diet consumed 37.6 kg −1 W day −1 and gained 120 g live weight per head per day. The results show that the sugar cane fraction F1 can provide a major part of a sheep's diet and achieve good weight gains. These experiments indicate that similar results may be obtained if the cane fractions are fed to cattle or goats and this may be particularly relevant in tropical countries.