Effects of Dry Pellet Diets on the Metabolic Rates of Bluegill (Lepomis macrochirus)

Abstract

Experiments were designed to evaluate the effects of 5 dry pellet diets containing various protein levels on metabolic rates and energy cost of food utilization of bluegill (L. macrochirus). In the 48-h period after feeding metabolic rates increased an average of 57% above base levels established prior to food presentation. The energy cost of food utilization, estimated as a percentage of ingested food energy, was .hivin.x 14.90 .+-. 0.96% SE (range 7.5-32.3%). Positive correlation was found between protein and caloric intakes and the increases in O2 consumption observed after feeding. Percent protein in the diet had no significant effect on mean values of O2 consumption after feeding or the estimates of the energy cost of food utilization. Probably the calorigenic effect of protein in fishes, which are principally ammonotelic, is considerably lower than that observed in ureotelic and uricotelic vertebrates. The mean estimate (14.90% of ingested energy) for the bluegill could reflect a low specific dynamic action of protein in conjunction with the calorigenic effect of the carbohydrate and lipid components of the diets.