The potential of land animal protein ingredients to replace fish meal in diets for cuneate drum, Nibea miichthioides , is affected by dietary protein level

A net pen experiment was carried out to examine the effect of dietary protein level on the potential of land animal protein ingredients as fish meal substitutes in practical diets for cuneate drum Nibea miichthioides . Two isocaloric basal (control) diets were formulated to contain 400 g kg −1 herring meal but two different digestible protein (DP) levels (400 versus 350 g kg −1 ). At each DP level, dietary fish meal level was reduced from 400 to 280, 200, 80 and 0 g kg −1 by incorporating a blend that comprised of 600 g kg −1 poultry by‐products meal (PBM), 200 g kg −1 meat and bone meal (MBM), 100 g kg −1 feather meal (FEM) and 100 g kg −1 blood meal (BLM). Cuneate drum fingerling (initial weight 42 g fish −1 ) were fed the test diets for 8 weeks. Fish fed the test diets exhibited similar feed intake. Final body weight, feed conversion ratio and nitrogen retention efficiency was not significantly different between fish fed the basal diets containing 350 and 400 g kg −1 DP. Weight gain decreased linearly with the reduction of dietary fish meal level at the 350 g kg −1 DP level, but did not decrease with the reduction of dietary fish meal level at the 400 g kg −1 DP level. Results of the present study suggest that fish meal in cuneate drum diets can be completely replaced with the blend of PBM, MBM, FEM and BLM at the 400 g kg −1 DP level, based on a mechanism that excessive dietary protein compensate lower contents of bio‐available essential amino acid in the land animal protein ingredients relative to fish meal.