Oxygen consumption, CO 2 excretion, and nitrogenous waste excretion (75% ammonia-N
and 25% urea-N) were measured daily in 4-g rainbow trout over a 15-day starvation period.
Oxygen consumption and CO 2 excretion declined while N excretion increased transiently in
the mid-part of the starvation period but was unchanged from control levels at the end.
Component losses (as percentage of total fuel used) of protein, lipid, and carbohydrate were
66.5, 31.1, and 2.4% respectively, as measured from changes in body weight and body …

The types of fuel burned by juvenile rainbow trout (17 g) during a 58-h period of aerobic
sustained exercise were studied by respirometry. Attempts to measure fuel usage by
depletion (the compositional approach) in these same fish were unsuccessful due to lack of
detectable changes in proximate body composition. O 2 consumption, CO 2 excretion, and
nitrogenous waste excretion (ammonia-N plus urea-N) were measured in individual fish
swum continuously at 55% and 80% of maximum sustainable swimming speed and in non …