Effects of enzymatic hydrolysates from poultry by-products (EHPB) as an alternative source of fish meal on growth performance, hepatic proteome and gut microbiota of turbot (Scophthalmus maximus)

This study was carried out to investigate the effects of enzymatic hydrolysates from poultry by-products (EHPB) as protein source on turbot (Scophthalmus maximus). For an eight-week feeding trial, the control group was fed a normal feed (0 EHPB), and the experimental groups were given four experimental diets, containing 80, 168, 255 and 340 g/kg EHPB, respectively. Results showed that 80 g/kg EHPB had no effect on the growth performance, and obviously increased the serum complement C3, complement C4 and SOD levels; >= 168 g/kg EHPB significantly decreased the crude fat content and triglyceride level, and increased the BUN and MDA levels; >= 255 g/kg EHPB significantly decreased the weight gain, apparent digestibility (AD) of nutrients, complement C3, complement C4 and SOD levels. The hepatic proteome analysis indicated that EHPB increased 5'-AMP-activated protein kinase (AMPK) level and might affect fat accumulation by regulating relevant enzymes. 16S rRNA sequencing showed that EHPB influenced the microbial community structure (R = 0.13, ANOSIMp = .006) and significantly decreased the abundance ofVibrio, but 255 g/kg EHPB increased the abundances ofPhyllobacterium,SphingomonasandDelftia, indicating that the high level of EHPB may induce accumulation of harmful substances in the intestine. Consequently, excessive EHPB impeded the growth and health status of fish, and about 80 g/kg EHPB is suitable for turbot growth and suppression of potential pathogens.