Dietary nucleotides are semi-essential nutrients for optimal growth of black tiger shrimp (Penaeus monodon)

Abstract

Nucleotides are essential to growth and development in mammals and some aquatic animals. Whilst much of the requirements for nucleotides can be met through de novo synthesis or salvage during cellular recycling, uptake through the diet is more energy-efficient. However, optimal dietary requirements are unknown for many species, and levels of nucleotide and their bioavailability in standard feed ingredients are largely unreported. The aim of this study was to determine the nucleotide requirement for maximal growth of black tiger prawn, Penaeus monodon. Initial dose–response trials using commercial mashes were confounded by high basal nucleotide levels therefore raw ingredients were analysed by HPLC for nucleotide content and a semi-purified diet was formulated with defined low nucleotide level. Using this as a base diet in a dose-titration study, results showed highly significant correlations between growth rates of prawns and concentrations of nucleotide in diets. Optimal nucleotide concentrations were predicted to be 0.564% at day 21 (R2 = 81.03%), 0.455% at day 42 (R2 = 88.19%) and 0.448 at day 63 (R2 = 63.18%), indicating a declining requirement for nucleotides with the increase in prawn size. In conclusions, raw ingredient analysis and a feeding trial indicated optimal requirements for dietary nucleotide in black tiger prawns ranged from 0.56 to 0.44% w/w. It is likely that some, or all, of the requirements can be met through naturally variable nucleotide in fishmeal. However, as fishmeal levels are reduced, driven by economics and sustainability, supplementation is likely to be required for optimal performance.