Dietary Alcalase-Derived Fish Protein Hydrolysate Supplementation Enhanced Growth Performance, Amino Acid Profiles, and Gut Health in Giant Trevally (Caranx ignobilis) Fed Low Fishmeal-Based Diets

The application of fish protein hydrolysates (FPHs) in aquaculture has achieved encouraging outcomes due to its growth and health promoting properties. This trial was carried out to detemine the effects of various alcalase-derived fish protein hydrolysate (FPH) supplementation on growth, feed utilization, proximate composition, liver and gut histology of juvenile giant trevally fed low fishmeal diets. Four tested diets (52% protein and 10% lipid) were produced, in which fishmeal and poultry meal (PM) were the main protein sources in the basal diet. 50 g/kg of each shrimp hydrolysate (SH), squid hydrolysate (SHH), and tuna hydrolysates (THs) were supplemented into the basal diet, namely SH, SHH, and TH, respectively. Fish were fed experimental diets in 56 days with four replicates per dietary group. The results reported that giant trevally fed SH, SHH and TH achieved higher growth than those fed the control. Feed intake (FI) didn’t alter, but lower feed conversion ratio (FCR) was seen in fish fed SH compared to the control, demonstrating that SH improved feed utilization. Protein and ash contents were increased in fish fed SH, SHH, and TH supplemented diets, whereas increased whole-body lipid was obtained in those fed TH. Dietary SH, SHH, and TH supplementations contributed to higher whole-body isoleucine, and higher lysine was seen in fish fed SH and TH. Total intestinal aerobic microbiota increased in fish fed SH, whereas Vibrio spp. density was relatively low among treatments. The goblet cells also increased in the intestine of the fish fed SH, indicating that SH could enhance intestinal health. The results indicated that all fish hydrolysates had beneficial effects of growth performance of juvenile giant trevally, in which SH showed more bioavailable than others, by improving feed efficiency and intestinal health.