Whole body and egg amino acid composition of silver pomfret, Pampus argenteus (Euphrasen, 1788) and prediction of dietary requirements for essential amino acids

Whole body and egg essential amino acid (EAA) composition of silver pomfret, Pampus argenteus, was determined to estimate their dietary requirements using A/E ratios as an indicator. Ten adult fish (sex ratio 1 : 1) were sampled each month from Kuwaiti waters for a 1-year period (November 2007 to October 2008). There was no significant difference (P > 0.05) between the whole body amino acid (AA) composition of males and females except for glutamic acid and serine. There were no significant differences (P > 0.05) between the contents of leucine, methionine, phenylalanine and threonine in whole body and eggs. However, arginine, isoleucine and valine contents in eggs were significantly higher than those of whole body, while lysine and histidine in whole body was significantly higher than that of eggs. Among non-essential AAs, cystine, tyrosine, alanine, and serine content in eggs were significantly (P < 0.05) higher than those in whole body. A high correlation between the whole body A/E ratios of silver pomfret with the A/E ratios for P. argenteus (r2 = 0.79), P. punctatissimus (r2 = 0.90), sea bream (r2 = 0.81), sea bass (r2 = 0.69) and Japanese flounder (r2 = 0.95) was observed. Based on a lysine requirement value of 4.5 g per 100 g protein for Asian sea bass, the EAA requirement values of histidine, leucine, lysine and threonine for silver pomfret estimated using whole body EAA composition was slightly higher than those of eggs values. On the other hand, arginine, isoleucine, Met + Cys, Phe + Tyr, and valine values estimated using egg composition in silver pomfret were slightly higher than those estimated by whole body composition. However, a higher correlation was observed with the whole body EAA composition and estimated EAA requirement values (r2 = 0.81) compared to that with eggs (r2 = 0.72). Until dose-response experiments are carried out to determine the EAA requirements precisely, the estimated EAA values using whole body EAA as proposed in this study could be used when formulating diets for silver pomfret.