Replacing fish meal with cottonseed meal protein hydrolysate affects growth, intestinal function, and growth hormone/insulin‐like growth factor I axis of juvenile blunt snout bream (Megalobrama amblycephala)

This study aimed to assess the effects of replacing fish meal with cottonseed meal protein hydrolysate (CPH) on the growth, intestinal function, growth hormone/insulin‐like growth factor I (GH/IGF‐I) axis, and inflammation of blunt snout bream, Megalobrama amblycephala. A total of 300 fish (38.66 ± 0.08 g) were allocated into five groups and fed either the basal diet (CPH 0) or the basal diet that replaced fish meal with 1% (CPH 1), 3% (CPH 3), 5% (CPH 5), and 7% CPH (CPH 7). Dietary CPH 3 increased the activities of protease, Na+/K+‐ATPase, amylase, creatine kinase, and γ‐glutamyl transpeptidase; microvillus length in the anterior and mid intestines; and the mRNA levels of GH, growth hormone receptor (GHR), and IGF‐I without any negative effects on growth. Dietary CPH 7 increased the mRNA levels of tumor necrosis factor‐α, interleukin‐6, IκB kinase alpha, and nuclear factor κB but decreased the transcript level of inhibitor of κB‐α (p