Growth, feed utilization and body composition of white sea bream diplodus sargus juveniles offered diets with various protein and energy levels

الملخص EN

White Sea bream Diplodus sargus is a valued table fish in the Mediterranean region and elsewhere (Black Sea and Easter Atlantic), and is a candidate aquaculture species in various countries.

Understanding dietary protein requirements and protein to energy ratios is imperative for development of a successful culture of this species.

A ten week experiment was performed to estimate growth performance of D.

sargus juveniles offered diets with various levels of protein and energy.

Six diets were formulated to contain three levels of protein (25, 35 and 45 %) plus two levels of lipids (8 and 12 %), and were offered to white sea bream juveniles in triplicate tanks, three times daily, to satiation.

Survival was greater than 93 % in all treatments.

Growth increased with increasing dietary protein and increasing lipid content of the diets.

Feed intake increased with increasing dietary protein but was not affected by dietary lipid levels.

Protein efficiency decreased with increasing dietary protein levels.

Moisture, protein and ash levels in the fish were not affected by dietary protein but body lipid content increased with increasing dietary protein.

Dietary protein levels seemed to affect red blood cells.

A greater proportion of immature red blood cells were found in blood of fish offered the 25 % and the 45 % protein diets than in blood of fish offered the 35 % protein diet.

Results of the present work suggest that a 45 % protein, 12 % lipid diet results in good growth of D.

sargus juveniles but might affect blood composition and thus be detrimental if offered to the fish for a long period of time.