4. Discussion
The tubiform foregut of kangaroos is comparable in form and
function to the haustrated equine colon, and as such we predicted that
the slope of the MRT–DMI curve for red kangaroos would be more like
that of horses (Fig. 2) rather than sheep. This was not the case and
there was little difference in the food intake patterns between sheep
and macropodid kangaroos generally. The slope of the DMI–MRTrelationship
for sheep and the red kangaroo were not significantly
different (Fig. 3). Consequently, our data did not support the
suggestion that kangaroos could maintain high intake levels with a
lesser reduction in digestive efficiency as compared with sheep.
Moreover, our data suggest that there is little difference between the
sheep and kangaroos in their ingestive responses to diet NDF contents
(Fig. 6); in other words there did not appear to be any fundamental
difference in the intake limitations of sheep and kangaroos due to
dietary NDF content, despite sheep possessing the particle-size
limitations on digesta flow unique to ruminants. Therefore, factors
other than differences in the particle-flow mechanisms of ruminants
and kangaroos must affect their DMI–MRT slope. Like the hindgutfermenting
equids, kangaroos are less restricted by particle-size
dependent flow of ingesta, but their DMI–MRT slope resembles that of
the ruminants.