Evaluation of fermented soybean meal in the practical diets for juvenile Chinese sucker, Myxocyprinus asiaticus

The study was designed to investigate the influence of fermented soybean meal (FSBM) on the growth and feed utilization of juvenile Chinese sucker, Myxocyprinus asiaticus. Seven isonitrogenous and isolipidic diets were formulated with 0%, 15%, 25%, 35%, 45%, 55% or 65% replacement of fish meal with FSBM on a protein basis. Each diet was fed to three replicate groups of fish with an initial weight 4.59 +/- 0.2 g for 8 weeks. Weight gain (WG) and specific growth rate (SGR) was significantly lower when FSBM inclusion was 391 g kg-1 or greater, replacing more than 45% fish meal protein. A significant negative relationship was observed between growth response and the level of fish meal protein replacement with FSBM. Methionine and Lysine content decreased as FSBM inclusion levels increased, consequently compromising growth performance. Feed intake (FI) were unaffected by dietary FSBM levels. The feed conversion ratio (FCR) of fish fed D-0, D-15, D-25 and D-35 diets was significantly lower than those fed other diets. The protein efficiency ratio (PER) was highest at the lowest FSBM inclusion level. Experimental diets D-0, D-15, D-25 and D-35 had apparent dry matter digestibility ranging from 71.2% to 72.6% and apparent protein digestibility (ADPs) from 89.1% to 90.1%, while the diets with higher FSBM inclusion (D-45 to D-65) had a significantly lower apparent dry matter digestibility range (69.770.3%) and ADPs range (88.588.9%). It is concluded that FSBM is an acceptable alternative plant protein source that can replace up to 35% of fish meal protein in diets without significant adverse effects on growth, survival, FCR, PER and body composition.