EFFECTS OF DIFFERENT PROTEIN SOURCES ON GROWTH PERFORMANCE AND METABOLISM-RELATED GENE EXPRESSION IN JUVENILE DARKBARBEL CATFISH (PELTEOBAGRUS VACHELLI)

A 66-day feeding trial was conducted to investigate the effects of different protein sources on growth, body composition and PEPT1 gene expression in the foreintestine and TOR gene expression in the liver of juvenile darkbarbel catfish initial weight (2.90 ± 0.01) g. Four isoproteic (39.0% crude protein) and isolipidic (9.0% crude lipid) diets were formulated with fish meal (FM), soy protein concentrate (SPC), fish hydrolysate (FH) and crystal amino acids (CAA) as the main protein source. No significant difference was observed in the survival rate among dietary treatments (P>0.05). Dietary protein had a significant effect on SGR. SPC group had lower SGR than that of the FM groups, while SPC group had higher SGR than FH and CAA group (P<0.05). The crude protein of SPC group was only lower than the FM group, while the crude lipid of SPC group was higher than the FM group (P<0.05). Dietary protein had a significant effect on PEPT1 mRNA expression. The PEPT1 mRNA expression in SPC group was significantly lower than the FM group, but significantly higher than the FH and CAA group at day 35. However, the PEPT1 mRNA expression of SPC group was significantly higher than the FM group at day 66 (P<0.05). Dietary protein source had no effect on TOR gene expression. These results suggested that juvenile darkbarbel catfish of SPC group had better growth performance than FH and CAA group, which might be attributed to the higher foregut PEPT1 mRNA expression.