Ration size and digestion in largemouth bass, Micropterus salmoides Lacépède

Abstract

Organic dry weight, protein N, lipid, and energy of contents in the stomach of largemouth bass decreased curvilinearly with time after a meal of lake emerald shiners, Notropis atherinoides. Time to evacuate the stomach increased with ration size. The proportionate change in time for a given percentage of gastric emptiness was independent of ration size. Proportionately more protein N than lipid was absorbed in the stomach. The pyloric caeca is an area of absorption particularly for protein N. In the intestine absorption of lipid was proportionately greater than that for protein N.Absorption efficiency of protein N, lipid, or energy did not differ significantly among the rations followed nor between the two size classes of bass. The overall geometric mean absorption efficiency for protein N was 95.7%, for lipid, 95.5%, and for energy, 89.6%. Initially the rate of absorption of protein N was highest for fish fed large rations. Differences in rate of absorption of lipid were not observed among the rations followed.