The influence of cellulose filler on feeding, growth and utilization of protein and energy in rainbow trout, Salmo gairdnerii Richardson

A nutrient source was diluted with indigestible filler in the form of α-cellulose. The trout compensated for up to 30% cellulose by increasing the total weight of food eaten, thereby stabilizing both nutrient intake and growth rate. The fish failed to compensate for levels of 40–50% cellulose and, despite evidence for an increase in the size of the stomach, nutrient intake was approximately halved. There was a slight reduction in food conversion efficiency and the growth rate declined accordingly. By contrast, faecal output rose considerably.