Ontogeny of biochemical phases of fertilized eggs and yolk sac larvae of gilthead seabream (Sparus aurata L.)

Abstract

Biochemical compositions of fertilized gilthead seabream (Sparus aurata) eggs and yolk sac larvae were determined at different periods (after hatching, 0th, 24th, 48th and 96th hours). Results showed that the yolk sac larvae and eggs contain more monounsaturated (MUFAs) and polyunsaturated (PUFAs) fatty acids than saturated fatty acids (SFAs). The changes observed in essential (EAA) and non-essential amino acid (NEAA) contents of fertilized eggs and yolk sac larvae through the experimental period were significant (P<0.05). Amylase and tyripsin activity was detected in fertilized eggs. Leucine alanine (LEU-ALA) peptidase activity was higher than other enzymatic activities throughout the experimental period. Aminopeptidase N(LAP) activity decreased from fertilized egg to hatching. After hatching, LAP activity increased until 24th hour and then decreased up to the beginning of exogenous feeding (P<0.05).The lowest alkaline phosphatase activity (AP) was taken from fertilized eggs. Then, AP activity tended to increase until the end of experimental period (P<0.05). In conclusion, our results can give information about the nutritional requirements of seabream larvae at the start of exogenous feeding.