Abstract
This experiment was conducted in order to examine the effect of extrusion processing on the nutritional value of brown fish meal diets for rainbow trout. The experimental diet con-taining ordinary brown fish meal (BFM-A) or low temperature-enzyme treated brown fish meal (BFM-B) was extruded (Ex) and steam pelleted (Pm), respectively. They were fed to rainbow trout (2.8g on average) for 12 weeks.
There were no marked differences in the growth rate of fish and apparent digestibility of protein and lipid between the Ex and Pm diets containing BFM-A. However, the Ex BFM-A diet was superior in feed efficiency, PER, and apparent digestibility of starch and energy. In the case of BFM-B, the growth rate, feed efficiency and PER were lower in fish fed on the Pm diet; nevertheless the Ex diet produced results comparable to the BFM-A diets. The apparent digestibility of starch in the BFM-B diets was also markedly improved by extrusion as observed with the BFM-A diets.
Thus, extrusion processing was found to improve the nutritional value of brown fish meal, especially the low temperature-enzyme treated form in terms of feed efficiency and PER.
