Tuna viscera hydrolysate products prepared by different enzyme preparations improve the feed intake and growth of Asian seabass, Latescalcarifer, fed total fishmeal replacement diets

Abstract

Protein hydrolysate products prepared using different enzymes at different degrees of hydrolysis (DH) may have different qualities when applied in a fish diet. In this study, hydrolysis enzymes, including endoproteinase from Bacilluslicheniformis (A), endoproteinase and exopeptidase from Aspergillus oryzae (F), and endoproteinase from B. amyloliquefaciens (N) were used to prepare tuna viscera hydrolysate products (TVHPs) at low (1) and high (2) DH (40 and 60%, respectively) for supplementation in fishmeal free diets for Asian seabass. The TVHPs were tested in a feeding trial composed of ten diets: A1- and F1-TVHP (50g/kg), F2- and A2-TVHP (25 g/kg) of diet, and N-hydrolysed TVHP (either low or high DH) at 25, 50, and 75 g/kg of diet. A control poultry by-product based diet and a fishmeal reference diet were included. Feed intake of fish fed the TVHP supplemented diets improved by 25.4-41.0% which significantly increased growth performance compared to the control groups (P<0.05). Growth response was better with diets containing 60% DH-TVHP suggesting that using a TVHP with a higher DH makes it possible to reduce the inclusion rate while still obtaining a performance benefit. In conclusion, the inclusion levels of TVHPs at 25-75 g/kg of diet could be suitable as a feeding stimulant in fishmeal free diets for this carnivorous fish.

Keywords

• tuna viscera
• degree of hydrolysis
• inclusion level
• feeding stimulant
• Asian seabass