The Israeli Journal of Aquaculture Bamidgeh 56(2), 2004, 113-125.

AMINO ACID PROFILES IN THE MIDGUT, OVARY, DEVELOPING EGGS AND ZOEA OF THE MUD CRAB, SCYLLA SERRATA

Veronica Dy Penaflorida*

Aquaculture Department, SEAFDEC, P.O. Box 256, Iloilo, Philippines



(Received 27.9.03, Accepted 20.1.04)


Key words: amino acids, eggs, mud crab, Scylla serrata, zoea


Abstract


Culture of the mud crab, Scylla serrata, is beset by low and inconsistent survival of larvae in spite of the high fecundity of crab breeders. The nutrition of the embryo and pre-feeding zoea depends on what is stored in the egg. The protein and free amino acid contents of the midgut gland, ovary, eggs, pre-feeding zoea, live food and a maintenance diet for broodstock were analyzed by HPLC. The maintenance diet had lower arginine, histidine, methionine, threonine and tryptophan than the ovary and egg. The midgut had higher phenylalanine and valine and lower leucine, methionine and tryptophan than the ovary. Amino acid profiles in the ovary, egg and zoea showed that methionine was highest in the ovary and leucine was highest in the zoea. Low values were observed for isoleucine and valine in ovary, arginine in egg, methionine and phenylalanine in zoea. When live foods were compared to zoea, histidine in Brachionus, leucine and tryptophan in Artemia, and arginine, leucine and valine in Acartia were low. Essential free amino acids in fertilized eggs were 2.5 times higher than in unfertilized eggs. Arginine, histidine, lysine, methionine, tyrosine and threonine decreased with egg embryogenesis, suggesting that these are the major free amino acids utilized as the egg develops. Information on egg and zoea amino acids can be used to predict viable crab eggs while information on amino acid profiles in the ovary, egg and zoea can be used to develop broodstock diets. Identification of limiting amino acids in live foods can be used to develop larvae diets.

* Tel: +63-335-1009, fax: +63-335-1008, E-mail: vpenaflorida2003@ yahoo.com
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