Abstract:
To investigate the effects of replacing fish meal by corn gluten meal (CGM) on fish growth, serum bioche-mical indices and liver histology, six isonitrogenous (45% crude protein) and isolipidic (10% crude lipid) diets with various dietary protein levels (0, 15%, 30%, 45%, 60% and 75%) (designated as C0, C15, C30, C45, C60, C75) were formulated to feed triplicate groups of juvenile large yellow croaker mean initial weight: (10.49±0.03) g for a 56 days trail. In addition, all diets except the control diet were supplemented with crystalline amino acids such as lysine and methionine. Results showed that the survival rate (
SR), specific growth rate (
SGR) and feed conversion ratio (
FCR) were not significantly affected (
P>0.05). Muscle crude protein content in C45 and C60 were significantly higher than that of C0 (
P<0.05). Muscle crude lipid content in C45 was significantly higher than that of C0, C15 and C75 (
P<0.05). Muscle moisture in C45, C60 and C75 were significantly lower than that of C0. CGM had no effects on crude protein, crude lipid and moisture of whole body (
P>0.05), while, the increased CGM replacement enhanced the whole body ash. CGM did not impact serum ALB, A/G, AST and GLU. The increasing dietary CGM level decreased total TC with a significant difference when the substitution level was more than 30% (
P<0.05). The serum TP and GLB content of C0 was significantly higher than that of C75 (
P<0.05). Serum AST of C60 and C75 were significantly higher than that of C0 (
P<0.05) with the highest in the C75. No significant differences were observed in the T-AOC, CAT and GHS-Px by CGM (
P>0.05). While CGM can increase the T-AOC content. Compared to C0 diet, C75 had significant and highest value in MDA (
P<0.05). From the liver histology, replacement proportion of fish meal by CGM more than 45% media-ted liver cell nucleus location and increased lipids accumulation that were translucent with vacuole. These results suggest that the optimal dietary protein level in juvenile large yellow croaker is about 45%.