Nutritional Evaluation of Soybean Meal for Rainbow Trout and Carp.

The nutritional quality of commercial defatted soybean meal (SBM) as a protein source was evaluated by determining apparent digestibility, PER, NPU, and BV. Two experiments were conducted using rainbow trout and carp with initial weights of 4.0 and 3.2g, respectively. They were fed diets containing SBM as the sole protein source at different protein levels from 0 to 75% for 20 days.The apparent protein digestibility was relatively high both in rainbow trout (92% on average) and in carp (91% on average). The PER, NPU, and BV values did not differ markedly between rainbow trout and carp, and generally decreased in proportion to increasing dietary protein levels. The PER, NPU, and BV values ranged between 1.8-4.3, 27.8-42.1, and 30.1-46.2 for rainbow trout, and 2.2-3.5, 32.9-37.4, and 36.0-42.2 for carp, respectively, at dietary protein levels of 11.0 to 33.6%. Growth and feed efficiency were relatively low in both species, which might be attributable to an inadequate amino acid profile of this protein meal. The body composition of neither species was greatly influenced by dietary protein levels.