Dietary Energy Budgets in Carp

Abstract

Dietary energy budgeting in carp was studied based on the energy requirements for maintenance of body weight and activity, and for maximum growth. Budgeting was determined by analyzing the whole body composition of carp and measuring the digestible and metabolizable energy values (DE and ME) of diets. Fish having a mean initial weight of 243.2 and 5.6 g were fed an experimental casein diet, and those of 3.9 g were fed a practical type of fish meal diet for 14 or 19 days, respectively. The energy partitionings of these diets based on gross energy (GE) intake (100%) at the level required for maximum growth were: 16.7-29.9% lost as fecal energy, 1.5-2.0% as non-fecal energy, 31.9-38.9% as heat increment, and 36.7-43.2% as net energy (12.6-15.5% as net energy for maintenance and activity and 24.1-27.7% as productive energy). The proportion of fecal energy value was relatively high and was greatly influenced by the quality of the diet, and the heat increment of feeding was found to occupy a large portion of the energy budgets in fish. The non-fecal energy loss increased proportionally to the DE intake. The non-fecal energy/DE rate was inversely related to the DE intake in fish receiving DE less than the maintenance requirement of fish body, but above this DE intake, the proportion remained constant.