Study of enzyme-hydrolyzed soybean replacing fish meal and/or chicken meal on the growth of channel catfish (Ictalurus punctatus)

Abstract

This study aimed to evaluate the effect of enzyme-hydrolyzed soybean (EHSB) to replace fish meal and chicken meal in channel catfish (Ictalurus punctatus) on the growth performance, serum biochemical indices and gastrointestinal structure of channel catfish. The channel catfish (initial weight: 21.25 ± 0.25 g) was fed four isonitrogenous, isolipidic and isophosphorous diets for 60 days. The control diet (CON group) contained 8% fish meal and 5% chicken meal. EHSB was used to replace fish meal (100%, RF group), chicken meal (100%, RC group), and 100% of fish meal and chicken meal (RFC group), respectively. The specific growth rate (SGR) and protein deposition rate (PR) of channel catfish in RF, RC and RFC groups were significantly increased compared to the control group and reached their peaks in RFC group (SGR: 2.92%, PR: 45.64%) (P < 0.05). The feed coefficient of channel catfish in RFC group (0.94) was significantly decreased compared to the control group (P < 0.05). The survival rate was not affected by the replacement of fish meal and chicken meal by EHSB (P > 0.05). The catalase and alanine aminotransferase activities in serum were significantly decreased in replacement groups compared to the control group (P < 0.05). Besides, the activities of superoxide dismutase and aspartate aminotransferase in serum of channel catfish were remarkably increased in the RFC group (24.22 U/L and 193.00 U/L, respectively) (P < 0.05). The replacement of fish meal and chicken meal by EHSB, either alone or simultaneously, significantly increased the crude protein (51.68% in RC group) and crude lipid (31.27% in RFC group) in whole body of channel catfish (P < 0.05). The crude lipid in muscle of channel catfish was markedly increased in RF (16.31%, dry matter) and RFC groups (16.45%, dry matter) (P < 0.05). Replacement of fish meal and chicken meal by EHSB could significantly increase the intestinal villi length and intestinal wall thickness, thus improving the digestive capacity of channel catfish. The gastric epithelial cells in the RFC group were plumper and more structurally integrated than in the control group. In summary, replacing 100% of fish meal and 100% of chicken meal with EHSB could effectively improve the growth performance, antioxidation and digestive capacities of channel catfish.