Abstract:The aim of this study was to investigate the effects of fishmeal replacement by soy peptide protein on the growth performance, body composition, digestive enzymes activity, and antioxidant capacity of yellow catfish (Pelteobagrus fulvidraco). The control group (A0) received 30% fishmeal, and the experimental groups received soy peptide protein substitutes at 17%, 33%, and 50% (A17, A33, and A50), and four kinds (A0, A17, A33, and A50) of iso-nitrogen compound feeds were prepared. There were 4 replicates and 30 juvenile yellow catfish per group [average body weight: (3.7±0.6) g], and the experiment ran for 80 days. The results showed that there were no significant differences in the growth performance of A17 and the control group (P>0.05). The weight gain rate of A33 was significantly higher than the control group (P<0.05), but there were no other differences (P>0.05). In A50, the feed coefficient ratio was significantly higher than the other groups (P<0.05), while the weight gain rate, specific growth ratio, and protein efficiency ratio were significantly lower than the other groups (P<0.05). There were no differences in the viscerosomatic and hepatosomatic indexes (P>0.05). Soy peptide protein substitution did not affect the contents of water, ash, or crude protein in yellow catfish (P>0.05). However, when the level of soy peptide protein increased from 33% to 50%, the crude fat content decreased significantly (P<0.05). The activities of intestinal lipase and amylase were significantly higher in the treatment groups (P<0.05), and the activity of gastric amylase in A33 and A50 was significantly higher than the control group (P<0.05). Soy peptide protein substitution did not affect malondialdehyde (MDA) activity in the liver. In conclusion, when fishmeal replacement was less than 33%, the growth performance of yellow catfish increased and there were no adverse effects on the antioxidation capacity of the liver. This is the first study to explore the effects of soy peptide protein replacement on P. fulvidraco growth and provides a reference for feed preparation and soy peptide protein use.
