The potential to replace dietary fish meal with corn gluten meal for golden pompano (Trachinotus ovatus)

An 8-week feeding trial was conducted to evaluate the potential of fish meal replacement with corn gluten meal (CGM) in diets for golden pompano (Trachinotus ovatus). A 2×3 layout was used. A basal diet (C) was formulated to contain 250 g/kg fish meal. In the test diets, 20, 40 and 60% of the fish meal in the basal diet was respectively replaced by either CGM (R) or γ-ray irradiated CGM (IR). The six test diets were abbreviated as R20, R40, R60, IR20, IR40 and IR60 (CGM was used as a fish meal substitute in diets R20, R40 and R60, and γ-ray irradiated CGM was used as a fish meal substitute in diets IR20, IR40 and IR60). All the diets were formulated at equal protein and lipid levels. Initial body weight of fish was (31.9±0.2) g. The results showed that weight gain, feed intake, feed conversion ratio (FCR), nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE) and body content of phosphorus were significantly affected by fish meal replacement level, while body phosphorus content was affected by the type of CGM used. Feed intake and weight gain decreased with increasing fish meal replacement level, regardless of CGM or γ-ray irradiated CGM as a fish meal substitute. At the same fish meal replacement level, no significant differences were found in the feed intake, weight gain, FCR, NRE, PRE, condition factor, hepatosomatic index and body composition (moisture, crude protein, crude lipid and ash) between fish fed the diets with fish meal replaced by CGM and γ-ray irradiated CGM. No significant differences were found in feed intake, weight gain, FCR and NRE between fish fed diets C and R20, suggesting that dietary fish meal level for T. ovatus can be reduced to 200 g/kg when CGM was used as a fish meal substitute. This study reveals that γ-ray irradiation could not improve CGM as a fish meal substitute in T. ovatus diet.