Evaluation of Enteromorpha prolifera as a feed component in large yellow croaker (Pseudosciaena crocea, Richardson, 1846) diets

A 9-week feeding trial was conducted to investigate the effects of dietary Enteromorpha prolifera on the growth performance and body composition of juvenile large yellow croaker (Pseudosciaena crocea) (Richardson, 1846) (11.41 +/- 1.59 g) in floating sea cages (1.5 x 1.5 x 2.0 m). Four isonitrogenous and isoenergetic diets were formulated to contain graded levels (0%, 5%, 10% and 15%) of E. prolifera. Survival ranged from 98.7% to 99.7%, and was independent of dietary treatment (P > 0.05). There were no significant differences in the feeding rate among dietary treatments (P > 0.05). The specific growth rate (SGR) increased with increasing levels of E. prolifera. When the supplementation of E. prolifera was > 5%, SGR was significantly higher compared with the control group (0%). The feed efficiency ratio (FER) in fish fed the diet with 5% E. prolifera (diet 2) was higher than that of the other groups, while in fish fed the diet with 10% E. prolifera (diet 3), it was the lowest (P < 0.05). The protein retention (PR) decreased as the level of E. prolifera increased in diets (5%, 10% and 15%). The protein body content displayed a trend similar to that of PR. No significant difference was observed in body moisture and ash among the dietary treatments. An increase in minerals of potassium, magnesium and sodium in body was observed with an increase in dietary seaweed concentrations. On basis of the SGR and FER, supplementation levels of E. prolifera can reach at least 15% without affecting the growth and still maintain a high survival rate for juvenile large yellow croaker.