Studies on the green liver in cultured red sea bream fed low level and non-fish meal diets: Relationship between hepatic taurine and biliverdin levels

The aim of this study was to investigate the cause of green liver in red se a bream fed substitute protein diets. Red sea bream Pagrus major was given either of the following diets for 28 weeks: (1) control diet (50% fish meal ), (2) low level fish meal diet (15% fish meal), and (3) non-fish meal diet (0% fish meal). The green liver was observed in all groups tested, but the incidence was much higher in the experimental diet groups. The feeding of substitute protein diets reduced plasma triglyceride and cholesterol levels . However, there was no significant difference in plasma hepatic enzyme act ivities and plasma bile salts concentration among the treatments. Fish fed the substitute protein diets showed low hepatic taurine levels with an appe arance of a biliverdin in the liver. Moreover, the proportion of ditaurobil irubin to total biliary bile pigments was significantly lower in fish fed t he substitute protein diets. These data indicate that feeding of substitute protein diets did not induce any cholestatic hepatobiliary obstructions an d that the low hepatic taurine level was one of the probable factors respon sible for the occurrence of green liver in red sea bream fed substitute pro tein diets.