The interactive effects of feeding and exercise on oxygen consumption, swimming performance and protein usage in juvenile rainbow trout (Oncorhynchus mykiss)

Derek H. Alsop, Chris M. Wood

Research output: Contribution to journalArticlepeer-review

225 Scopus citations


The impacts of feeding on the rate of O2 consumption (M(O2)), aerobic swimming performance, nitrogenous waste excretion (ammonia-N and urea-N) and protein utilization as an aerobic fuel were investigated in juvenile rainbow trout. Feeding trout to satiation (in groups of 120) resulted in rapid growth and elevated routine M(O2) by 68 % relative to fasted fish and by 30% relative to trout fed a maintenance ration of 1% of body mass daily. This in-tank M(O2) of satiation-fed trout was approximately 70 % of the M(O2max) observed at the critical swimming speed (U(crit)) when trials were performed on individual trout in swimming respirometers. Feeding increased M(O2) at all swimming speeds; the absolute elevation (specific dynamic action or SDA effect) was dependent on ration but independent of swimming velocity. There was no difference in M(O2max) at U(Crit) amongst different ratioN treatments, but U(Crit) was significantly reduced by 15 % in satiation-fed fish relative to fasted fish. These results suggest that the irreducible SDA load reduces swimming performance and that M(O2max) is limited by the capacity to take up O2 at the gills and/or to deliver O2 through the circulatory system rather than by the capacity to consume O2 at the tissues. Ammonia-N and urea-N excretion increased with protein intake, resulting in a 6.5-fold elevation in absolute protein use and a fourfold elevation in percentage use of protein as an aerobic fuel for routine metabolism in satiation-fed trout (50-70%) relative to fasted fish (15%). Urea-N excretion increased greatly with swimming speed in all treatments, but remained a minor component of overall nitrogen excretion. However, even in satiation-fed fish, ammonia-N excretion remained constant as swimming speed increased, and protein did not become more important as a fuel source during exercise. These results suggest that the reliance on protein as a fuel is greatly dependent on feeding quantity (protein intake) and that protein is not a primary fuel for exercise as suggested by some previous studies.

Original languageEnglish (US)
Pages (from-to)2337-2346
Number of pages10
JournalJournal of Experimental Biology
Issue number17
StatePublished - Sep 1 1997


  • Critical swimming speed
  • Feeding
  • Fuel
  • Nitrogen quotient
  • Oncorhynchus mykiss
  • Protein
  • Rainbow trout
  • Routine and swimming oxygen consumption

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Agricultural and Biological Sciences (miscellaneous)


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