Two 7-week feeding trials were conducted to evaluate the capacity of golden pompano (Trachinotus ovatus) to use soy protein concentrate (SPC) as a dietary fish meal substitute. In trial I, fish were fed a control diet containing 40% fish meal and other four diets had the fish meal replaced by 20, 40, 60 or 80% SPC. In trial II, a 3 × 2 design was used, and 40 and 80% of the fish meal in control diet was replaced by SPC, with or without 5 g/kg taurine supplementation.
In trial I, no significant difference was found in the feed intake between feeding treatments. The weight gain and nitrogen retention efficiency (NRE) decreased, whereas the feed conversion ratio (FCR) and phosphorus retention efficiency (PRE) increased, with decreasing dietary levels of fish meal. No significant differences were found in the weight gain, FCR and NRE between fish fed control diet and the 20% replacement diet. Fish fed the control diet and/or the 20% replacement had higher weight gain than those fed diets containing higher levels of SPC.
In trial II, no significant differences were found in the feed intake, weight gain, FCR, NRE and PRE between fish fed the control diet and those containing taurine. No significant differences were found in the condition factor, hepatosomatic index and body composition between fish fed the various treatments. The present study reveals that taurine supplementation can elevate fish meal replacement level by SPC in the golden pompano diets. Fish meal in the diet can be reduced from 40 to 32% if the fish meal is replaced with SPC (without taurine supplementation), and the fish meal can be further reduced to 24%, if the substituted with SPC plus 5 g kg−1 taurine.