Application prospect of replacement of fish meal with spray-dried egg meal in diets for swimming crab (Portunus trituberculatus)

Abstract

An 8-week feeding trial was conducted to evaluate the effects of replacing fish meal with spray-dried egg meal (SEM) on growth performance, anti-oxidative capacity, mTOR pathway, and cholesterol metabolism in juvenile Portunus trituberculatus. The results showed that the highest percent weight gain was observed in crabs fed diet with 10% replacement of fish meal with SEM. Essential amino acids in the muscle and hepatopancreas significantly decreased with the increase of dietary replacement levels of fish meal with SEM. The lowest content of MDA in hepatopancreas was occurred at those fed diet with 40% replacement of fish meal with SEM, the activities of T-AOC, GSH-PX and content of GSH in hepatopancreas significantly increased with dietary SEM replacement fish meal increasing from 10% to 50%. The expression of akt, eif4e1a, eif4e2, eif4e3, and 4ebp1 significantly up-regulated, however, the expression of tor was showed significantly linear down-regulated, and the highest expression of akt, eif4e2 and 4ebp1 were found in crabs fed diet with 20% replacement of fish meal with SEM, the highest expression of eif4e1a was observed in those fed diet with 10% replacement of fish meal with SEM, the highest expression of eif4e3 was occurred in crabs fed diet with 30% replacement of fish meal with SEM. In cholesterol metabolism, the expression of abcg1 and lrp2 significantly down-regulated and the expression of npc1 significantly up-regulated with increase of replacement level of fish meal with SEM. The content of T-CHO in hemolymph and hepatopancreas significantly linear increased. In conclusion, based on quadratic broken-line regression analysis of PWG against the dietary replacement of fish meal with SEM, the optimal replacement level of fish meal with SEM was estimated to be 15.94% for juvenile swimming crab.