Abstract :
The energy cost of eating was measured in four goats averaging 38 kg and fitted with rumen
cannulas. Heat production (HP) was estimated in each goat over restricted periods of approximately
15 min while standing and eating continuously in a confinement respiration chamber. The animals
were given feeds of different nature and physical form ranging from shrubs to concentrates. The
energy cost of eating was calculated from the increment in HP above the average HP during the
prefeeding period. The energy cost was related to the type and amount of feed consumed and also to
the time spent eating. In a parallel experiment, similar amounts of the feeds eaten normally (oral
feeding) were introduced into the rumen through a fistula. The increases in HP during and after
fistula-feeding were negligible, which indicates that all of the increase in HP during eating is to be
attributed to the energy cost of eatingper se, mainly to the act of food prehension, mastication and
propulsion in the alimentary tract. The rate of ingestion (g DMlmin) ranged from 6.3 for fresh cut
lucerne (Medicago sutiVa) to 46-99 for concentrates. The energy cost of eating (Jkg body weight
(BW) per g DM) averaged 7.08 for fresh cut lucerne, 9.02 for roughages and 1.55 for concentrates
and was 2-24 and 4.75 for pelleted and chopped lucerne hay respectively. When the energy cost was
expressed as a function of time spent eating, it ranged from 45 to 144 Jkg BW per min, depending
on the physical form of the feed.
