Dietary Enzyme-Hydrolyzed Marine Proteins Supplementation Promotes Appetite, Enhances Lipid and Protein Metabolism in Litopenaeus Vannamei Fed Reduced Fish Meal Diets

Abstract

An 8-weeks feeding trial was conducted to evaluate the effect of dietary enzyme-hydrolyzed marine protein (EMP) supplementation on appetite, protein and lipid metabolism of Litopenaeus vannamei fed reduced fishmeal diets. The control group was supplemented with 30% fishmeal, in the experimental group, 28% fish meal was supplemented with 1% EMP (1% EMP), and 26% fish meal with 2% EMP (2% EMP). The results showed that there were no significant differences in growth performance in each group (P > 0.05). Shrimp in control group exhibited higher total cholesterol, triglyceride and low-density lipoprotein cholesterol in hemolymph than those in the other groups (P < 0.05). The results of intestinal histology showed that shrimp fed with 1% EMP diet exhibited higher fold height and fold width than those fed the other diets (P < 0.001). Compared with control group, the lipid catabolism genes and regulatory factors (atgl, hsl, ampkα, ampkγ, acox1) was significantly enhanced in 1% EMP group (P < 0.05). Moreover, the neurotransmitter and appetite related-genes expressions (such as oa-ta, tdc, tbh and ghs-r1) in 1% EMP group of cerebral ganglion were significantly up-regulated than those in other group (P < 0.05). Dietary 1% EMP supplementation activated expressions of TORC1 pathway-related genes (tor, rheb, slc3a2, 4e-bp) in the hepatopancreas than those feed the control diet (P < 0.05). In conclusion, the results revealed that reducing 2% fish meal and adding 1% EMP in the diet could improve the appetite, lipid and protein metabolism, intestinal and hepatopancreas health of juvenile Pacific white shrimp.

Keywords: Enzyme-hydrolyzed marine protein, appetite, protein synthesis, Lipid metabolism, Pacific white shrimp