Kikuyu (Pennisetum clandestinum) intake determined by alkanes administered in a xantham gum suspension

Abstract

The alkane method of measuring herbage intake in ruminants was compared with actual intake determined by transponder-controlled feed gates (Calan gates). Kikuyu (Pennisetum clandestinum) intakes of yearling bulls (Holstein-Friesland and Hereford) were measured for a period of seven days. No significant effect of breed on intake was found. Herbage intake calculated from the alkane technique (mean of morning and afternoon faecal sampling times) compared favourably with actual intake with an average intake of 6.25 kg DM/day (93 g DM/kg W0.75/day) (CV 22%). However, a significant effect in the faecal sampling times on intake was observed. Herbage intake determined from alkane concentrations in the faecal samples that were collected in the morning underestimated actual intake by 11%, while intake calculated from faecal alkane concentrations of samples that were collected in the afternoon overestimated actual intake by 8%. It is hypothesised from this study that the dosing of the alkane (dotriacontane) should be every 12 hours when administered in a xantham gum suspension