Partial replacement of fish meal by several plant proteins with or without iron and lysine supplement in diets for juvenile Chinese sucker, Myxocyprinus asiaticus

Two feeding experiments were conducted to evaluate the potential of fermented soybean meal (FSBM), corn gluten meal (CGM) and cottonseed meal (CSM) with or without lysine (L) and iron (Fe) to replace fish meal (FM) in practical diets of juvenile Chinese sucker. In experiment I, four experimental diets (430gkg(-1) crude protein on dry matter basis) were formulated. Diet containing FM as the main protein source was used as a control (Diet 1). Diets 2-4 had 300 g kg(-1) FM protein replaced with FSBM, CGM or CSM protein without iron or lysine supplement. Fish (average weight, 1.82 +/- 0.01g) were hand-fed twice daily for 8weeks. In experiment II, juvenile Chinese sucker (average weight, 3.40 +/- 0.08g) were fed one of five experimental diets twice daily for 8weeks. Diet 1 in experiment I was used as a control and Diet 4 in experiment I, with ferrous sulphate, with lysine or with both ferrous sulphate and lysine were used as the experimental diets (designated as FM, CSM, CSM+Fe, CSM+L and CSM+Fe&L, respectively). Results from the two feeding trials indicated that about 300 g kg(-1) of FM protein can be replaced by FSBM, CGM or CSM with lysine supplement in Chinese sucker diets without adversely affecting growth. CSM with iron could not improve the growth performance. CSM without lysine supplement significantly affected the growth performance, body composition and digestive enzyme activities.