A balanced amino acid diet improves<i>Diplodus sargus</i>larval quality and reduces nitrogen excretion

Abstract

Fish larvae present high amino acid requirements due to their high growth rate.Maximizing this growth rate depends on providing a balanced amino acid diet which can fulfil larval amino acid nutritional needs.In this study two experimental microencapsulated casein diets were tested: one presenting a balanced amino acid profile and another presenting an unbalanced amino acid profile.A control diet, live feed based, was also tested.Trials were performed with larvae from 1 to 25 DAH.Microencapsulated diets were introduced at 8 DAH in co-feeding with live feed and at 15 DAH larvae were fed the microencapsulated diets alone.Results showed a higher survival for the control group (8.6 ±1.3% versus 4.2 ± 0.6% and 3.2 ± 1.8%) although dry weight and growth were similar in all treatments.The proportion of deformed larvae as well as the ammonia excretion was lower in the group fed a balanced diet than in the unbalanced or control groups (38.3% deformed larvae in control, 30% in larvae fed unbalanced diet and 20% on balanced diet group).Furthermore, larvae fed the microencapsulated diets presented higher DHA and ARA levels.This study demonstrates that dietary amino acid profile may play an important role in larval quality.It also shows that balanced microencapsulated diets may improve some of the performance criteria, such as skeletal deformities, compared to live feeds.