Amino Acid Requirements of Gilthead Bream (<i>Sparus aurata</i>) Juveniles

Abstract

In one trial 120 gilthead bream fingerlings received tow different feed mixtures containing two different levels of protein (diet A.400 and B 360 gkg-1). The average initial live weight was about 2.2 ±0.1 g fish-1 in each replicate of all treatments. Twenty fish per aquarium were stocked randomly in 6 glass aquaria (120 l each). Fish were fed with experimental diets at rate 8 % of the body weight daily. The amino acids (AA) content was in the diets, whole fish and muscle at the end of the growth period (60 days). The results indicated that, at the end of experiment Sea bass fry had reached an average live weight 18.5 and 16.2 g fish-1 for fish fed diet A and B respectively. Also the increase of protein levels in the feed to 40% caused a significant decrease in the content of indispensable amino acid (IAA) and dispensable amino acid (as %v of whole fish and muscle of wet weight). Tow methods were subsequently used to estimate the quantitative IAA requirements of Sea bass fry based on the hypothesis that (a) the dietary requirement pattern of IAA reflects the tissue pattern and (b) the rate of daily deposition in the fish can be equated with the dietary requirement as percentage of 100 g-1 diet. The quantitative IAA requirement (%) of Sea bass (Dicentrarchus labrax) diets as follow: Lysine 2.27, Methionine 1.09, Therionine 0.61, Leucine 2.4, Isoleucine 0.47, Histidine1.6, Arginine 1.39, Phenylalanine 1.43, Valine 1.22 and Tryptophane 0.42.