NUTRITIONAL MODELLING OF PROTEIN, AMINO ACID AND ENERGY REQUIREMENTS OF TIGER GROUPER Epinephelus fuscoguttatus.  

Igor Pirozzi
 
Port Stephens Fisheries Institute, NSW Department of Primary Industries, Taylors Beach. NSW 2316. Australia.
 
Centre for Sustainable Tropical Fisheries and Aquaculture & College of Science and Engineering, James Cook University, Townsville, Queensland 4811, Australia.
 
igor.pirozzi@jcu.edu.au

Tiger grouper are a high value marine fish species yet relatively little information is available describing their basic nutritional requirements for protein and energy. Nutritional modelling has been successfully applied to many aquaculture species to provide quantitative estimates of nutrient and energy requirements throughout growth production. While models have been developed for several species describing protein and energy requirements, few have considered the requirements for essential amino acids.

This study used a bioenergetic approach to quantify the digestible protein, amino acid and energy utilisation efficiencies, maintenance requirements, carcass composition and growth potential of tiger grouper. The daily digestible protein (DP) intake to achieve maximum predicted protein retention efficiency was 2.0 g DP kg-0.7 day-1. The utilization efficiency of dietary protein for tiger grouper was 0.58 with the corresponding cost of DP per unit of protein gain was 1.71 g g-1. The daily digestible energy (DE) intake (kJ DE kg-0.8 day-1) to achieve a maximum predicted energy retention efficiency was 101 kJ DE kg-0.8 day-1.  The utilization efficiency of energy for tiger grouper was 0.63 and equates to an energetic cost of production of 1.59 kJ DE kJ-1 energy deposition. Utilisation efficiencies for digestible MET, LYS and HIS were 0.51, 0.54 and 0.30 respectively (Fig. 1). The reciprocal cost of production for these essential amino acids per unit gain was 2.0, 1.8 and 3.4 g g-1 respectively.

Detailed understanding of nutrient and energy requirements of tiger grouper throughout production will provide a platform to improve feed management and feed formulation.