Abstract
In this series of studies on nutritional energetics in carp and rainbow trout, the present study was conducted to determine the energy requirements for maintenance of body weight and activity, and for maximum growth in the latter fish by feeding them a casein diet, a quality experimental fish meal diet (FD), and a commercial diet (CD) at different feeding levels.
When the fish received the casein diet, the digestible energy (DE) requirements for maintenance of body weight and activity were 26.8, 23.0, and 20.9 kcal/kg body weight/day, and the feeding rates to satisfy these requirements were 0.63, 0.55, and 0.49% of body weight/day in fishof 1.4, 9.1, and 73.8g initial body weight, respectively. The DE requirements of those for maximum growth were 90-100, 80-90, and 60-70 kcal/kg body weight/day, and the corresponding feeding rates were 2.1-2.4, 1.9-2.2, and 1.4-1.6% of body weight/day. These energy requirements slightly decreased with increase of fish body weight, being comparatively lower in rainbow trout than those in mammals.
The DE requirements of fish weighing 23.7g fed FD and CD for maintenance of body weight and activity were 16.0 and 12.6 kcal/kg body weight/day, being 0.38 and 0.40% of body weight/day respectively based on feeding rates, indicating little difference between the two diets. In this experiment, dietary energy budgets were also determined.
