Alsop D, Wood C
J Exp Biol. 1997;200(Pt 17):2337-46. doi: 10.1242/jeb.200.17.2337.
The impacts of feeding on the rate of O2 consumption (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 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 O2 of satiation-fed trout was approximately 70% of the O2max observed at the critical swimming speed (UCrit) when trials were performed on individual trout in swimming respirometers. Feeding increased 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 O2max at UCrit amongst different ration treatments, but UCrit 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 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.
研究了摄食对虹鳟幼鱼耗氧率（O₂）、有氧游泳能力、含氮废物排泄（氨氮和尿素氮）以及蛋白质作为有氧燃料的利用率的影响。将虹鳟喂至饱足（每组120尾），其生长迅速，与禁食鱼相比，常规耗氧量提高了68%，与每日投喂体重1%维持日粮的虹鳟相比提高了30%。当在游泳呼吸仪中对个体虹鳟进行试验时，饱足投喂虹鳟在水槽中的耗氧量约为临界游泳速度（UCrit）下观察到的最大耗氧量（O₂max）的70%。摄食使所有游泳速度下的耗氧量增加；绝对增加量（特殊动力作用或SDA效应）取决于日粮水平，但与游泳速度无关。不同日粮处理组在UCrit时的O₂max没有差异，但饱足投喂的鱼与禁食鱼相比，UCrit显著降低了15%。这些结果表明，不可减少的SDA负荷会降低游泳能力，且O₂max受鳃摄取O₂和/或通过循环系统输送O₂的能力限制，而非受组织消耗O₂的能力限制。氨氮和尿素氮排泄随蛋白质摄入量增加而增加，导致饱足投喂的虹鳟（50 - 70%）相对于禁食鱼（15%），绝对蛋白质利用率提高了6.5倍，蛋白质作为常规代谢有氧燃料的利用率提高了四倍。在所有处理中，尿素氮排泄随游泳速度大幅增加，但在总氮排泄中仍占较小比例。然而，即使是饱足投喂的鱼，随着游泳速度增加，氨氮排泄仍保持不变，且蛋白质在运动过程中并非更重要的燃料来源。这些结果表明，对蛋白质作为燃料的依赖很大程度上取决于摄食量（蛋白质摄入量），且蛋白质并非如先前一些研究所表明的那样是运动的主要燃料。
